Patent Application
20190043636
Battery active materials are evaluated using numerous material characterization techniques for fundamental understanding, comparative analysis during research and development, and for quality control during manufacturing. Electrochemical properties of the active materials also need to be investigated and validated, and this analysis is very time and material intensive generally requiring electrode fabrication, cell assembly and cell cycling. In addition, evaluating active materials electrochemically in battery cells can be complicated by the electrode microstructure and the contributions of other components within the cell that are not the active materials.
In various embodiments, a method of characterizing a dispersion includes electrically applying an excitation signal to the dispersion and measuring an electrical response elicited by the excitation signal. The dispersion includes electrically and/or ionically conductive particles and a liquid carrier; and the particles are mechanically perturbed.
In various embodiments, a method of characterizing a dispersion includes electrically applying an excitation signal to the dispersion; and measuring an electrical response elicited by the excitation signal. The dispersion includes electrically conductive particles of a lithium-ion conducting material and an aqueous electrolyte; and the particles are mechanically perturbed by flowing the dispersion including the particles through an electrochemical cell that includes a channel.
In various embodiments, a system for characterizing a dispersion includes an anode, a cathode, an electrolyte; and a dispersion that includes electrically conductive particles and a liquid carrier. In various embodiments, the system includes any suitable reference electrode described herein.
Advantageously, in various embodiments, the method can measure the resistance of electroactive particles in which the primary contribution to the resistance results from the particles themselves. Advantageously, in various embodiments, the measurements of the method can be completed on timescale three orders of magnitude less than the coin cell validation of the aging impact on rate capability.
The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments of the present invention.
Reference will now be made in detail to certain embodiments of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.
Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.
In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section.
In the methods described herein, the acts can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.
The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.
The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of” as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that the composition is about 0 wt % to about 5 wt % of the material, or about 0 wt % to about 1 wt %, or about 5 wt % or less, or less than, equal to, or greater than about 4.5 wt %, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt % or less. The term “substantially free of” can mean having a trivial amount of, such that a composition is about 0 wt % to about 5 wt % of the material, or about 0 wt % to about 1 wt %, or about 5 wt % or less, or less than, equal to, or greater than about 4.5 wt %, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt % or less, or about 0 wt %.
In various embodiments, a method of characterizing a dispersion includes electrically applying an excitation signal to the dispersion and measuring an electrical response elicited by the excitation signal. The dispersion includes electrically and/or ionically conductive particles and a liquid carrier; and the particles are mechanically perturbed.
The excitation can include a specified voltage or series of voltages applied to the dispersion and the electrical response includes a measured current. The excitation can also include a specified current or series of currents applied to the dispersion and the electrical response includes a measured voltage. The excitation signal can result in either oxidation or reduction of the electrically conductive particles in the dispersion. Thus, the current or voltage excitation can be induce oxidization or reduction of the conductive particles, depending on the composition of particles used.
Perturbing the particles can include agitating the particles in a vessel, such as an electrochemical cell. Perturbing or agitating the particles can include flowing the dispersion including the particles through an electrochemical cell that includes a channel. Flowing of the dispersion can include the flow of the dispersion through one or more channels in an electrochemical cell, which can be effected by any suitable means for moving fluids. For example, a peristaltic pump can be used to move the dispersion through one or more channels, and/or through fluid inlets and fluid outlets. In various embodiments, the particles are mechanically perturbed during the measuring or before the measuring.
Suitable flow rates for the dispersion can be about 5 mL/min to about 400 mL/min. In various embodiments, the flow rate for the dispersion can be about 5 mL/min to about 350 mL/min, about 5 mL/min to about 300 mL/min, about 5 mL/min to about 250 mL/min, about 5 mL/min to about 200 mL/min, about 5 mL/min to about 150 mL/min, about 5 mL/min to about 100 mL/min, about 10 mL/min to about 400 mL/min, about 20 mL/min to about 400 mL/min, about 5 mL/min to about 400 mL/min, about 5 mL/min to about 400 mL/min, about 50 mL/min to about 400 mL/min, about 75 mL/min to about 400 mL/min, about 100 mL/min to about 400 mL/min, about 150 mL/min to about 400 mL/min, or about 200 mL/min to about 400 mL/min. The flow rate of the dispersion can be about 5 mL/min, 25 mL/min, 45 mL/min, 65 mL/min, 85 mL/min, 105 mL/min, 125 mL/min, 145 mL/min, 165 mL/min, 185 mL/min, 205 mL/min, 225 mL/min, 245 mL/min, 265 mL/min, 285 mL/min, 305 mL/min, 325 mL/min, 345 mL/min, 365 mL/min, 385 mL/min, or 400 mL/min.
The electrochemical cell can include an anode, a cathode, a permeable membrane between the anode and cathode, and a fluid inlet and a fluid outlet. Fluid can flow into the electrochemical cell through fluid inlet and out of through the fluid outlet,
Perturbing the particles can also include stirring the dispersion including the particles in an electrochemical cell. Stirring of the dispersion in the electrochemical cell can be accomplished using any suitable means, such as using a stir bar and magnetic stir plate. The dispersion can be stirred at a rate of about 50 rpm to about 2500 rpm, about 50 rpm to about 2250 rpm, about 50 rpm to about 2000 rpm, about 50 rpm to about 1750 rpm, about 50 rpm to about 1500 rpm, about 50 rpm to about 1250 rpm, about 50 rpm to about 1000 rpm, about 50 rpm to about 750 rpm, about 50 rpm to about 500 rpm, about 50 rpm to about 250 rpm, about 100 rpm to about 2500 rpm, about 250 rpm to about 2500 rpm, about 500 rpm to about 2500 rpm, about 750 rpm to about 2500 rpm, or about 1000 rpm to about 2500 rpm. In various embodiments, the stir rate of the dispersion can be about 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm, 1050 rpm, 1100 rpm, 1150 rpm, 1200 rpm, 1250 rpm, 1300 rpm, 1350 rpm, 1400 rpm, 1450 rpm, 1500 rpm, 1550 rpm, 1600 rpm, 1650 rpm, 1700 rpm, 1750 rpm, 1800 rpm, 1850 rpm, 1900 rpm, 1950 rpm, 2000 rpm, 2050 rpm, 2100 rpm, 2150 rpm, 2200 rpm, 2250 rpm, 2300 rpm, 2350 rpm, 2400 rpm, 2450 rpm, or 2500 rpm.
In various embodiments, the electrochemical cell includes an anode, a cathode, and a stir bar. In various embodiments, the electrochemical cell can include a reference electrode that can be any suitable reference electrode described herein. When the electrochemical cell is configured to include a stir bar, the dispersion can be stirred for 1 to 30 minutes at any specified stir rate described herein. After stirring for the specified time, the characteristics of the dispersion can be measured according to the methods described herein. In various embodiments, the dispersion is stirred while measuring the electrical response.
In various embodiments, the method further includes measuring at least two electrical responses to determine a resistance of the dispersion. Determining the resistance of dispersion can also include measuring at least three, four, five, six, seven, eight, nine, or ten electrical responses. The measuring of at least two electrical responses, in various embodiments, takes about 1 minute to about 120 minutes, 1 minute to about 100 minutes, 1 minute to about 90 minutes, 1 minute to about 80 minutes, 1 minute to about 70 minutes, 1 minute to about 60 minutes, 1 minute to about 50 minutes, 1 minute to about 40 minutes, 1 minute to about 30 minutes, 1 minute to about 20 minutes, 1 minute to about 10 minutes, 5 minutes to about 120 minutes, 10 minutes to about 120 minutes, 15 minutes to about 120 minutes, 20 minute to about 120 minutes, 25 minutes to about 120 minutes, 30 minutes to about 120 minutes, 40 minutes to about 120 minutes, 50 minutes to about 120 minutes, or 60 minute to about 120 minutes. In various embodiments, the measuring of at least two responses can take 1 minute, 2 minutes, 3 minutes, 4 minutes, 5, minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes.
In various embodiments, the liquid carrier includes an electrolyte. The electrolyte can be an aqueous electrolyte. Suitable aqueous electrolytes can include, without limitation, any water-soluble lithium or sodium salt, such as Li2SO4, LiNO3, lithium oxalyldifluoroborate, LiBF4, Li3PO4, LiClO4, LiF, Na2SO4, NaNO3, sodium oxalyldifluoroborate, NaBF4, Na3PO4, NaClO4, NaF, and combinations thereof. In various embodiments, the electrolyte is aqueous Li2SO4. The concentration of the aqueous lithium or sodium salt can be from about 0.01 M to about 5 M, about 0.1 M to about 5 M, about 0.5 M to about 4 M, about 0.5 M to about 3 M, or about 0.5 M to about 2 M. The concentration of the aqueous lithium or sodium salt can be about 0.01 M, 0.05 M, 0.1 M, 0.5 M, 1 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, 4.5 M, or 5.0 M.
In various embodiments, the electrolyte is an organic electrolyte. The organic electrolyte can include an organic solvent such as, without limitation, acetonitrile, N-methylpyrrolidine (NMP), dimethoxyethane (DME), dichloromethane, hexamethylphosphoramide (HMPA), dimethylformamide (DMF), tetrahydrofuran (THF), ethyl methyl carbonate, ethylene carbonate, propylene carbonate, and mixtures thereof. Other suitable organic solvents can include fluorinated and perfluorinated organic solvents, such as fluorinated lactones, fluorinated linear carboxylates, fluorinated cyclic carbonates, fluorinated linear carbonates, fluorinated monoethers, fluorinated diethers; boron-containing solvent such as borate esters and cyclic borate esters; phosphorus-containing solvents such as organic phosphates, phosphites, phosphonates, phosphazenes, and phosphonamidates; sulfur containing solvents such as ethyl methyl sulfone and sulfolane, and including solvents containing sulfide, sulfoxide, sulfone, sulfite, sulfonate, and sulfate, and mixtures of any of the foregoing organic solvents.
In various embodiments, the organic electrolyte includes at least one salt that is suitable for use as a salt in an organic electrolyte. The salt can be, for example, LiPF6, LiBF4, LiClO4, fluoroorganic lithium salts such as (RSO2)3CLi, (RSO2)2NLi, and RSO2OLi, where R is a fluorinated or perfluorinated C1-C5 alkyl, and mixtures thereof. Exemplary fluoroorganic lithium salts include lithium bis(trifluoromethansulfonyl)imide (LiTFSI). The concentration of the salt in the organic electrolyte can be from about 0.01 M to about 5 M, about 0.1 M to about 5 M, about 0.5 M to about 4 M, about 0.5 M to about 3 M, or about 0.5 M to about 2 M. The concentration of the salt in the organic electrolyte can be about 0.01 M, 0.05 M, 0.1 M, 0.5 M, 1 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, 4.5 M, or 5.0 M.
In various embodiments, the conductive particles include an alkali metal ion conducting material. The alkali metal ion conducting material can be a lithium-ion conducting material, a sodium-ion conducting material, and mixtures thereof. The lithium-ion conducting material can include LiFePO4 (LFP), Li4Ti5Oi2 (LTO), LiFeMnPO4, LiCoO2, LiMn2O4, LiNiMnCoO2 (NMC), LiNiCoAlO2, and mixtures thereof. In various embodiments, the lithium-ion conducting material is LFP or LTO. In various embodiments, the conductive particles themselves undergo an electrochemical reaction, where the particles become oxidized or reduced. The conductive particles, in various embodiments, do not cause oxidation or reduction in any of the components of the electrolyte in which they are dispersed.
In various embodiments, at least about 80% of the electrical resistance is due to the conductive particles. Without being bound by theory, the resistance measurements obtained with the methods described herein are due to collisions of particles with an electrode. In contrast, conventional methods typically have particles connected to the electrode statically through some form of processing for analysis/characterization. In various embodiments, at least about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 94%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 99.9% of the resistance is due to the conductive particles. The electrical resistance can be the resistance measured using the methods herein.
The conductive particles can have a charge or discharge capacity of about 0.01 mAh/g to about 400 mAh/g, about 0.1 mAh/g to about 350 mAh/g, about 0.1 mAh/g to about 300 mAh/g, about 0.1 mAh/g to about 250 mAh/g, about 0.1 mAh/g to about 200 mAh/g, about 0.1 mAh/g to about 150 mAh/g, about 0.1 mAh/g to about 100 mAh/g, about 0.1 mAh/g to about 50 mAh/g, about 1 mAh/g to about 350 mAh/g, about 5 mAh/g to about 350 mAh/g, about 10 mAh/g to about 350 mAh/g, about 25 mAh/g to about 350 mAh/g, about 50 mAh/g to about 350 mAh/g, about 100 mAh/g to about 300 mAh/g, about 110 mAh/g to about 250 mAh/g, or about 110 mAh/g to about 200 mAh/g. In various embodiments, the conductive particles can have a charge or discharge capacity of about 120 mAh/g to about 170 mAh/g. The conductive particles can have a charge or discharge capacity of about 0.01 mAh/g, 0.05 mAh/g, 0.1 mAh/g, 1 mAh/g, 5 mAh/g, 10 mAh/g, 25 mAh/g, 50 mAh/g, 75 mAh/g, 100 mAh/g, 110 mAh/g, 120 mAh/g, 130 mAh/g, 140 mAh/g, 150 mAh/g, 160 mAh/g, 170 mAh/g, 180 mAh/g, 190 mAh/g, 200 mAh/g, 220 mAh/g, 240 mAh/g, 260 mAh/g, 280 mAh/g, 300 mAh/g, 320 mAh/g, 340 mAh/g, 360 mAh/g, 380 mAh/g, or 400 mAh/g.
The dispersion can include about 0.001 vol % to about 20 vol % of the conductive particles. In various embodiments, the dispersion can include about 0.005 vol % to about 20 vol %, 0.01 vol % to about 20 vol %, 0.05 vol % to about 20 vol %, 0.1 vol % to about 20 vol %, 0.5 vol % to about 20 vol %, 1 vol % to about 20 vol %, 0.001 vol % to about 15 vol %, 0.001 vol % to about 10 vol %, 0.001 vol % to about 5 vol %, 0.1 vol % to about 10 vol %, or 0.5 vol % to about 5 vol %. The dispersion can include about 0.001 vol %, 0.05 vol %, 0.1 vol %, 0.5 vol %, 1 vol %, 1.5 vol %, 2 vol %, 2.5 vol %, 3 vol %, 3.5 vol %, 4 vol %, 4.5 vol %, 5 vol %, 5.5 vol %, 6 vol %, 6.5 vol %, 7 vol %, 7.5 vol %, 8 vol %, 8.5 vol %, 9 vol %, 9.5 vol %, 10 vol %, 12 vol %, 14 vol %, 16 vol %, 18 vol %, or 20 vol %. The vol % can be computed based on the volume and mass of electrolyte together with the mass of particles added. The density of the particles can be used to convert to volume, and a vol % can be obtained.
The conductive particles can have a BET surface area of about 0.01 m2/g to about 500 m2/g, about 0.01 m2/g to about 450 m2/g, about 0.01 m2/g to about 400 m2/g, about 0.01 m2/g to about 350 m2/g, about 0.01 m2/g to about 300 m2/g, about 0.01 m2/g to about 250 m2/g, about 0.01 m2/g to about 200 m2/g, about 0.01 m2/g to about 150 m2/g, about 0.01 m2/g to about 100 m2/g, about 0.01 m2/g to about 90 m2/g, about 0.01 m2/g to about 80 m2/g, about 0.01 m2/g to about 70 m2/g, about 0.01 m2/g to about 60 m2/g, about 0.01 m2/g to about 50 m2/g, about 0.01 m2/g to about 40 m2/g, about 0.01 m2/g to about 30 m2/g, about 0.01 m2/g to about 20 m2/g, about 0.05 m2/g to about 500 m2/g, about 0.1 m2/g to about 500 m2/g, about 0.5 m2/g to about 500 m2/g, about 1 m2/g to about 500 m2/g, about 5 m2/g to about 500 m2/g, about 10 m2/g to about 500 m2/g, about 25 m2/g to about 500 m2/g, about 50 m2/g to about 500 m2/g, about 75 m2/g to about 500 m2/g, about 100 m2/g to about 500 m2/g, about 150 m2/g to about 500 m2/g, about 200 m2/g to about 500 m2/g, about 300 m2/g to about 500 m2/g, or about 350 m2/g to about 500 m2/g. In various embodiments, the conductive particles can have a BET surface area of about 0.01 m2/g, 0.05 m2/g, 0.1 m2/g, 0.5 m2/g, 1 m2/g, 5 m2/g, 10 m2/g, 15 m2/g, 20 m2/g, 25 m2/g, 30 m2/g, 35 m2/g, 40 m2/g, 45 m2/g, 50 m2/g, 100 m2/g, 150 m2/g, 200 m2/g, 250 m2/g, 300 m2/g, 350 m2/g, 400 m2/g, 450 m2/g, or 500 m2/g. In various embodiments, the particles can have a BET surface area of about 0.5 m2/g to about 25 m2/g.
In various embodiments, the method further includes aging the dispersion for about 1 minute to about 30 days, about 1 minute to about 25 days, about 1 minute to about 20 days, about 1 minute to about 18 days, about 1 minute to about 16 days, about 1 minute to about 14 days, about 1 minute to about 12 days, about 1 minute to about 10 days about 1 minute to about 5 days, about 1 minute to about 2 days, about 5 minutes to about 30 days, about 15 minutes to about 30 days, about 30 minutes to about 30 days, about 60 minutes to about 30 days, about 120 minutes to about 30 days, about 240 minutes to about 30 days, or about 360 minutes to about 30 days to provide an aged dispersion; and detecting a change in the resistance of the aged dispersion compared to an identical dispersion that is not aged. Aging the dispersion can include preparing any of the dispersions described herein and letting the dispersion stand in a suitable container at room temperature (about 25° C.) for the specified time. Aged dispersion that settle during the aging process can be re-suspended to form a dispersion prior to the characterization of the dispersion. The dispersion can be aged for about 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 30 minutes, 60 minutes, 120 minutes, 240 minutes, 360 minutes, 1 day, 2 days, 3 days, 4 days, 5, days, 6 days, 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days, 14 days, 15 days, 16 days, 17 days, 18 days, 19 days, 20 days, 21 days, 22 days, 23 days, 24 days, 25 days, 26 days, 27 days, 28 days, 29 days, or 30 days.
In various embodiments, a method of characterizing a dispersion includes electrically applying an excitation signal to the dispersion; and measuring an electrical response elicited by the excitation signal. The dispersion includes electrically conductive particles of a lithium-ion conducting material and an aqueous electrolyte; and the particles are mechanically perturbed by flowing the dispersion including the particles through an electrochemical cell that includes a channel. In various embodiments, the lithium-ion conducting material is LFP or LTO. In various embodiments, the aqueous electrolyte is Li2SO4.
In various embodiments, a system for characterizing a dispersion includes an anode, a cathode, an electrolyte; and a dispersion that includes electrically conductive particles and a liquid carrier. In various embodiments, the system includes any suitable reference electrode described herein.
At least one of the anode or cathode can be a metal, such as a precious metal or a non-precious metal. Precious metals can include, without limitation, silver, platinum, gold, palladium, and combinations thereof. Non-precious metals can include, without limitation, lithium, aluminum, copper, nickel, titanium, aluminum, stainless steel, and combinations thereof. The anode or cathode can have any suitable shape not inconsistent with the methods described herein. Suitable shapes for the anode and cathode can include, without limitation, serpentine, straight line, mesh, flat plate, disc, cylinder, branched, and forest. In various embodiments, at least one of the anode or the cathode has a serpentine shape. In various embodiments, the cathode includes aluminum. In various embodiments, the anode includes lithium. In various embodiments, the cathode includes gold. In various embodiments, the anode includes platinum.
In various embodiments, the liquid carrier includes an electrolyte. The electrolyte can be an aqueous electrolyte. Suitable aqueous electrolytes can include, without limitation, any water-soluble lithium or sodium salt, such as Li2SO4, LiNO3, lithium oxalyldifluoroborate, LiBF4, Li3PO4, LiClO4, LiF, Na2SO4, NaNO3, sodium oxalyldifluoroborate, NaBF4, Na3PO4, NaClO4, NaF, and combinations thereof. In various embodiments, the electrolyte is aqueous Li2SO4. The concentration of the aqueous lithium or sodium salt can be from about 0.01 M to about 5 M, about 0.1 M to about 5 M, about 0.5 M to about 4 M, about 0.5 M to about 3 M, or about 0.5 M to about 2 M. The concentration of the aqueous lithium or sodium salt can be about 0.01 M, 0.05 M, 0.1 M, 0.5 M, 1 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, 4.5 M, or 5.0 M.
In various embodiments, the electrolyte is an organic electrolyte. The organic electrolyte can include an organic solvent such as, without limitation, acetonitrile, N-methylpyrrolidine (NMP), dimethoxyethane (DME), dichloromethane, hexamethylphosphoramide (HMPA), dimethylformamide (DMF), tetrahydrofuran (THF), ethyl methyl carbonate, ethylene carbonate, and mixtures thereof. Other suitable organic solvents can include fluorinated and perfluorinated organic solvents, such as fluorinated lactones, fluorinated linear carboxylates, fluorinated cyclic carbonates, fluorinated linear carbonates, fluorinated monoethers, fluorinated diethers; boron-containing solvent such as borate esters and cyclic borate esters; phosphorus-containing solvents such as organic phosphates, phosphites, phosphonates, phosphazenes, and phosphonamidates; sulfur containing solvents such as ethyl methyl sulfone and sulfolane, and including solvents containing sulfide, sulfoxide, sulfone, sulfite, sulfonate, and sulfate, and mixtures of any of the foregoing organic solvents.
In various embodiments, the organic electrolyte includes at least one salt that is suitable for use as a salt in an organic electrolyte. The salt can be, for example, LiPF6, LiBF4, LiClO4, fluoroorganic lithium salts such as (RSO2)3CLi, (RSO2)2NLi, and RSO2OLi, where R is a fluorinated or perfluorinated C1-C5 alkyl, and mixtures thereof. Exemplary fluoroorganic lithium salts include lithium bis(trifluoromethansulfonyl)imide (LiTFSI). The concentration of the salt in the organic electrolyte can be from about 0.01 M to about 5 M, about 0.1 M to about 5 M, about 0.5 M to about 4 M, about 0.5 M to about 3 M, or about 0.5 M to about 2 M. The concentration of the salt in the organic electrolyte can be about 0.01 M, 0.05 M, 0.1 M, 0.5 M, 1 M, 1.5 M, 2.0 M, 2.5 M, 3.0 M, 3.5 M, 4.0 M, 4.5 M, or 5.0 M.
In various embodiments, at least about 80% of the electrical resistance is due to the conductive particles. Without being bound by theory, the resistance measurements obtained with the methods described herein are due to collisions of particles with an electrode. In contrast, conventional methods typically have particles connected to the electrode statically through some form of processing for analysis/characterization. In various embodiments, at least about 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 94%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%, or 99.9% of the resistance is due to the conductive particles. The electrical resistance can be the resistance measured using the methods herein.
In various embodiments, the conductive particles themselves undergo an electrochemical reaction, where the particles become oxidized or reduced. The conductive particles, in various embodiments, do not cause oxidation or reduction in any of the components of the electrolyte in which they are dispersed.
In various embodiments, the system further comprises a fluid inlet and a fluid outlet. In various embodiments, the dispersion including the conductive particles flows through the fluid inlet and fluid outlet. Fluid can flow into the electrochemical cell through the fluid inlet and out through the fluid outlet,
In various embodiments, the system further comprises a permeable separator between the anode and the cathode. In various embodiments, the permeable separator can prevent cross-mixing of the positive and negative electrolytes, but still allow the transport of ions to complete the circuit during the passage of current. The permeable separator can have high ionic conductivity, low water intake and be chemically and thermally stable. In various embodiments, the permeable separator is an anion exchange membrane or a cation exchange membrane. Cation exchange membranes contain negatively charged groups such as —SO3−, —COO−, —PO32−, —PO3H−, and/or —C6H4O−. Anion exchange membranes have positive functional groups such as —NH3+, —NRH2+, —NR2H+, —NR3+, and/or —SR2+. In various embodiments, the permeable separator is a perfluorinated ion exchange membrane. The permeable separator can be about 5 μm to 100 μm thick. In various embodiments, the permeable separator can at least one polymer such as polypropylene, polyethylene, polybutylene, polyvinyl chloride, polystyrene, polyurethane, polysilane, and mixtures and co-polymers thereof. In various embodiments, the permeable separator can have at least one, at least two, at least three, at least four, or more layers of any of the materials described herein.
In various embodiments, the anode and the cathode are disposed between two non-conductive polymer surfaces (e.g.,
In various embodiments, the system can operate in batch mode in which the electrochemical characteristics of a series of materials have their DPR measured sequentially. After each material is measured, the electrochemical cell can be flushed out with an electrolyte solution, and a new material can be measured.
In various embodiments, a non-transitory computer-readable storage medium having computer-executable instructions stored thereon which, when executed by one or more processors, cause an apparatus to perform at least a portion of a technique for determining dispersed particle resistance (DPR) as described herein. The apparatus can include or can be coupled to an analytical instrument such as a chronoamperometer, a chronopotentiometer, or a combination thereof. The analytical device can measure the DPR of a sample of particles in a dispersion. The apparatus can provide a user interface that includes a plurality of user-editable fields for entering sample characteristics such as, for example, sample weight and/or sample density, and a user interface element that when triggered, sends a signal to the analytical device to measure the characteristics of the sample or to otherwise perform one or more techniques as shown and described elsewhere herein.
Various embodiments of the present invention can be better understood by reference to the following Examples which are offered by way of illustration. The present invention is not limited to the Examples given herein.
Six different LFP materials were characterized, referred to herein as LFP-1, LFP-2, LFP-3, LFP-4, LFP-5, and LFP-6. These materials were purchased from different suppliers and used as received. Scanning electron microscope (SEM) images were taken for all LFP materials with a Quanta 650 SEM to characterize the morphologies of the powders. A Panalytical X'pert diffractometer with Cu Kα radiation was used to obtain the X-ray diffraction (XRD) patterns of the materials between 20 values of 15 and 65 degrees. Tap densities were measured with a tap density analyzer with sample volumes of ˜6 mL in a 10-mL graduated cylinder (Quantachrome Instruments). Thermogravimetric analysis (TGA) of the LFP samples in air was conducted with a TA Instruments Q50. TGA was performed at a ramp rate of 5° C. min-1 from room temperature to 800° C. BET surface area of the LFP materials was determined with a surface area and pore size analyzer using nitrogen as the probe gas (NOVA 2200e). The Fe concentration of the electrolyte was measured using inductively coupled plasma optical emission spectroscopy (ICP) analysis (PerkinElmer Optima 8000). The typical concentration range for ICP analysis was 0.1 to 100 ppm for the element Fe. To prepare ICP samples, the electrolyte was carefully separated from the remaining solid LFP particles via filtration and then diluted to the desired concentration. The Fe concentration reported was the average of three separate measurements. The standard deviations of all ICP measurements were less than 1% of the reported average values.
All LFP materials were characterized electrochemically first using conventionally fabricated coin cells. Electrochemical characterizations were carried out using CR2032-type coin cells with a LFP electrode as the working electrode and lithium foil as the counter and reference electrode, separated by a polypropylene/polyethylene/polypropylene trilayer membrane. LFP electrodes were prepared by first mixing 60 wt % LFP powder with 20 wt % carbon black and 20 wt % polyvinylidene difluoride (PVDF) binder, which was dissolved in N-methylpyrrolidone (NMP, Sigma-Aldrich®). Relatively high carbon content was used to ensure good connectivity and high conductivity between LFP particles and relatively high binder content was used to provide good mechanical robustness of the electrode films and adhesion to the current collector. For coin cells made to demonstrate the impact of excess carbon in the LFP samples, electrodes were also fabricated without any additional carbon black additive. These electrodes were comprised of 90 wt % LFP powder and 10 wt % PVDF binder. The mixtures were then pasted on an aluminum foil using a doctor blade with a gap thickness of 125 μm.
Electrodes were dried in an oven at 70° C. overnight and further dried in a vacuum oven at 70° C. for an additional three hours while applying vacuum. Electrode disks of 1.6 cm2 were prepared using a punch, and the loading of LFP active material in the electrodes for all samples was ˜4 mg. The electrolyte for the coin cell measurements was 1.2 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with EC/EMC=3:7 volume ratio (BASF Corporation). The cells were assembled in an argon-filled glove box (with concentrations of both O2 and H2O<1 ppm) at room temperature. The galvanostatic charge-discharge cycling of coin cells were performed with a Maccor battery cycler. Where C rates are reported, they were determined by first measuring the gravimetric capacity of the LFP materials at 17 mA g−1 LFP (measured capacities varied between 145 and 160 mAh g−1 LFP). Then, the actual measured capacity at the low discharge rate was used for scaling C rates (e.g., for measured 160 mAh g−1 LFP, 0.1 C was 16 mA g−1 LFP, 1 C was 160 mA g−1 LFP, and so on.). The cycling voltage window for LFP cells was 2.5 to 4.0 V (vs. Li/Li+).
The aqueous electrolyte used for LFP suspensions was 1 M Li2SO4 (Fisher Scientific) dissolved in distilled water. LFP suspensions were prepared by dispersing LFP powders into the aqueous electrolyte agitated by a magnetic stir bar at 500 rpm for 5 minutes before electrochemical measurements, consistently for all measurements. Different loadings of LFP suspensions (0.2 vol %, 0.4 vol %, 0.7 vol %, 1.0 vol %, 1.5 vol %, 2.0 vol %, 3.0 vol %, and 4.0 vol %) were also prepared to characterize the effect of loading on the measured resistance. A customized cell was designed and assembled to electrochemically characterize the suspensions (
The LFP materials were characterized using XRD, SEM, TGA, BET, and tap density first to confirm their material properties.
Conventional coin cells were then fabricated and cycled to evaluate electrochemical performance. The voltage profiles for the LFP materials at increasing rates of discharge (from 0.1 C to 10 C, all charge cycles were at 0.1 C) are shown in
The capacity retention (in terms of the percentage of the discharge capacity relative to the capacity at 0.1 C) at increasing rates, or rate capability, generally followed the order of LFP-1>LFP-2>LFP-3>LFP-4>LFP-5>LFP-6. LFP-4 showed slightly higher capacity retention than LFP-3 at 5 C, although at this high current (˜2 mA cm−2) the lithium metal anode may begin to impact the measurements. These electrochemical measurements established the benchmark order of rate capability among the six LFP materials which were within identically processed composite electrodes.
DPRs for LFP materials were measured using the following procedure. After dispersing a LFP powder in aqueous electrolyte, the suspension was electrochemically evaluated in a custom cell (shown in
The average value of the current increased linearly with the increase in the applied potential.
DPR values of a material can be influenced by a few key factors besides the intrinsic electrochemical properties of the active material, including, without limitation, the electrochemical cell design (cell size, wire length and geometry), suspension flow rate, and active material loading. The same cell was used for each series of measurements to exclude any cell variability, and the flow rate was also kept constant for all measurements. Material samples were evaluated in the flow cell in a sequential manner, with a rinsing step of passing LFP-free electrolyte through the cell preceding each new suspension measurement. To investigate the effect of active material loading in greater detail, LFP suspensions with different volumetric loadings were characterized in succession in a high throughput manner with the electrochemical flow cell (as an example LFP-1 is shown in
The DPR values decreased as LFP loadings increased for all LFP materials, and rate of decrease of DPR with increasing loading decreased as the loading increased. Both observations were consistent with electrochemical reactions of varying numbers of particles from the suspension on average in contact with the electrode. As active material loading increased, more particles were in contact with the current collector electrode on average at any given time and hence were participating in electrochemical reactions and the measured oxidation currents. The particles in contact with the electrode can each be considered as resistors connected in parallel. At higher volume fractions of LFP, there were more particles on the electrode surface, resulting in more resistors in parallel and hence decreased total resistance which decreased the measured DPR. Not only was the decrease in DPR with increased loading consistent with more resistors/particles in parallel, but the proportional relationship between LFP loading and resistance also supports this analysis. If resistance from a single particle in contact with the current collector was Ri, then the collective resistance of N particle resistors in parallel (RN) can be calculated with Equation 1:
Assuming the random sampling of the ensemble of particles in the dispersion to be relatively consistent, a representative resistance for each particle from a given LFP sample can be defined as R0. This assumption should be reasonable because the number of particles was large even at low loadings and for a large batch of LFP sample there was not any particle sorting or separation to bias any particular dispersion. Using the assumption of a representative single resistance for each LFP sample, RN would be R0/N. Thus, the resistance due to the active materials, which dominates DPR measurements, may be expected to be inversely related with the number of active material particles in contact with the current collector and hence inversely related with the volumetric active material loading—at least at relatively low loadings of active material where the current collector surface was readily accessible. The inverse relationship between volumetric active material loading and DPR was supported by a least squares fit of the DPR measurements as collected at increasing loadings shown in
The inverse relationship between DPR and volumetric particle loading provided further evidence that DPR measured the collective resistance of the active material particles. The inverse relationship between volumetric loading and DPR was analogous to previously reported experiments of the relationship between active material loading and area specific impedance in coin cells. In both cases, the increase in particles participating in electrochemical reactions decreased the total cell resistance with an inverse relationship between particle loading and total measured resistance. Volumetric loading of 2 vol % LFP was chosen for further comparison between LFP materials because 1) the change in resistance above 2 vol % was relatively small, 2) higher loadings required more material and as an analytical technique smaller sample size was desirable, and 3) at very low loadings of LFP in some cases the variation in the measured resistance was relatively high, likely because at lower loadings the DPR measurement became more stochastic which resulted in more significant swings in the distribution of particles on the current collector relative to the mean distribution.
Lower DPR for a given material indicated that material should have a slower increase of overpotential at increasing current, and thus for appropriate materials processed into equivalent electrodes and battery cells, a material with a lower DPR could in general be expected to correlate to a higher voltage and better capacity retention at increasing currents. Thus, for a given set of materials those with lower DPR values could be expected to have better rate capability. DPR on LFP was a single measurement of multiple resistances, but was expected to be dominated by the ionic or electronic resistance of the active material particles. The total resistance in conventional electrodes is more complex and highly dependent on the fabrication process—though importantly DPR has the advantage of reducing the system complexity to identify what fraction of a cell resistance may be due to the active material. DPRs for all six LFP materials at 2 vol % were measured and the results are shown in
This DPR trend was generally consistent with expectations based on the relative rate capability order of these LFP materials, where the material with the lowest DPR had the highest rate capability and the material with the highest DPR had the lowest rate capability. The standard deviations were also very small relative to the measured DPR values, indicating good data consistency. DPR values were consistent for successive measurements of the same material over the measurement timescales of less than half an hour, and thus aging effects of the electrolyte (discussed in more detail herein) did not impact the relative DPR measurements in
The relatively high 20 wt % carbon was originally chosen to minimize the contact and matrix resistance in the electrode such that the electrochemical performance was primarily limited by the resistance from the LFP active materials. To further demonstrate the impact of the high carbon in the LFP-5 material, coin cells were fabricated without any added carbon (composite electrode contained only active material and binder) and these electrodes were cycled in coin cells (for cycling profiles see
LFP-5 had better electrochemical performance than both LFP-3 and LFP-4 (two materials that had better rate capability than LFP-5 in electrodes with additional conductive additive, see
As an example to demonstrate the sensitivity of the DPR technique, measurements were made on the same LFP material both pristine and after aging in the electrolyte. LFP has previously been reported to have reduced electrochemical performance after being aged in water or aqueous electrolyte. After aging, measured impacts to LFP include increased electrode polarization, decreased capacity, dissolution of chemical species, and in some cases a change in the crystalline phases observed in the material. These performance decays can even occur during storage in humid environments, thus the storage history of LFP materials can be very important. LFP changes due to contact with water in many cases proceeded slowly, and detecting these changes can be challenging without fabricating electrodes with the LFP material and performing electrochemical evaluation. As mentioned herein, this procedure can be very time consuming. The method described herein, in various embodiments, allows for the fast detection of the electrochemical performance decay of LFP.
As an initial demonstration of the concept of detecting LFP aging using DPR, LFP-3 was mixed with 1 M Li2SO4 electrolyte and aged for 15 days. After aging, the LFP was rinsed, dried, and then fabricated into electrodes and evaluated in conventional coin cells via identical procedures for the LFP batteries described earlier. A representative example of LFP-3 coin cell discharge capacity at different cycling rates, using LFP-3 material both before and after aging in electrolyte for 15 days is shown in
This performance impact was consistent with other reports on aged LFP materials in aqueous electrolyte or water. DPR tests were also conducted for both unaged and aged LFP-3 at a loading of 2 vol %. The aged LFP had a 30% increase of DPR from the unaged material (from 467.8Ω to 626.1Ω). This 10-minute DPR measurement detected a significant change in the aged material, indicating that DPR has the sensitivity to detect aging effects in LFP that can dramatically impact rate capability. Aged LFP did not have any significant changes in the XRD pattern relative to the pristine material (
The DPR measurements described above were able to identify variations in relative rate capability between different materials and changes to the rate capability of a material due to aging. These rate capability changes, and corresponding DPR resistances, reflect the resistance of the active material particles during electrochemical oxidation. The total resistance due to the LFP active material can be dependent on the ionic and/or electronic conductivity of the particles, the size of the particles, and the number of particles contributing to the electrochemical reactions. Thus, if the particle size distribution of the LFP particles is determined from another technique, DPR can be used to determine the initial conductivity of LFP particles.
Another lithium-ion battery active material used to demonstrate the method in this report was the anode material Li4Ti5O12 (LTO). LTO was chosen because it is a well characterized lithium-ion battery anode material with high rate capability, and the rate capability has previously been demonstrated to vary significantly across LTO material produced using different methods. The flat discharge potential of LTO is beneficial for measuring a stable potential when using constant current testing. Three LTO materials from either different suppliers or synthesized in lab were first characterized in conventional coin cells using existing methods to measure the capacity retention at increased rates of discharge and the mass electrode resistance. Three LTO materials were used in this study, which we refer to as LTO-1, LTO-2, and LTO-3. LTO-1 and LTO-3 were obtained from battery material vendors. LTO-2 material was synthesized following a solid state calcination method previously published in the literature. A mixture of anatase titanium oxide (Acros Organics) and lithium hydroxide (Fisher Scientific, 4% excess than stoichiometric amount) was calcined in a Carbolite CWF 1300 box furnace in an air atmosphere by heating at an incremental rate of 3° C. min−1 up to 800° C. and then holding at this temperature for 20 hours before turning off the furnace and allowing cooling down to ambient temperature without control over the cooling rate. To characterize the morphologies of the materials, scanning electron microscope (SEM) images were taken for all three LTO materials with a Quanta 650 SEM (
Electrochemical characterizations were carried out using CR2032-type coin cells with LTO electrode as the working electrode and lithium foil as the counter and reference electrode, separated by a polypropylene/polyethylene/polypropylene trilayer membrane. LTO electrodes were prepared by first mixing 80 wt % LTO powder with 10 wt % carbon and 10 wt % polyvinylidene difluoride (PVDF) binder, which was dissolved in N-methylpyrrolidone (NMP, Sigma-Aldrich®). The mixtures were pasted on aluminum foil using a doctor blade. Electrodes were then dried in the oven at 70° C. overnight followed by further drying in a vacuum oven at 70° C. for three hours. Electrode disks of 1.6 cm2 were prepared using a punch, and the loading of LTO active material in the electrodes for all samples was ˜10 mg. The electrolyte used was 1.2 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) and ethyl methyl carbonate (EMC) with EC/EMC=3:7 by volume ratio (BASF Corporation). The cells were assembled in an argon-filled glove box (with concentrations of both O2 and H2O<1 ppm) at room temperature. The galvanostatic charge-discharge tests of coin cells were performed with a Maccor battery cycler. For experimental results where the C rate is given, 1 C was assumed to be 175 mA g−1 LTO active material, with the rate scaled by the amount of active material loaded into each individual electrode. The cycling window for LTO cells was 1.0 to 2.5 V (vs. Li/Li+).
LTO suspensions were prepared by dispersing the LTO powder in the electrolyte (using agitation provided by a magnetic stir bar at 400 rpm). Three different loadings of LTO suspensions (0.5 vol %, 1 vol % and 2 vol %) were prepared for each LTO material. Loadings were kept low to minimize the formation of larger particle flocculates. A customized cell was designed and assembled to characterize the suspensions. As shown in
The LTO materials were electrochemically tested in conventional coin cells to determine the rate capability for benchmarking. Both the discharge profiles and the discharge capacities at increasing rates of discharge (cells were cycled between 0.1 C and 10 C) are shown in
Using the discharge profiles at various discharge currents in
Although Rm is a valuable parameter to use that correlates to the rate capability of active materials, it still requires electrode and cell fabrication and many charge/discharge cycles at different rates which take significant time. Also, while Rm in many cases is dominated by the resistance of the active material itself, it is also influenced by other factors in the electrode, such as the particle “wiring.” Also, the influence of active material loading is compensated by the mass term in Rm only within a particular range of loading. The electrode microstructure still influences the Rm value measured, and thus a method to interrogate the active material without electrode microstructure effects would be desirable. A technique that does not involve electrode fabrication to electrochemically probe the active materials could in principle remove the contributions from electrode microstructure and non-active material components.
A customized electrochemical cell was designed (shown in
Thus, the DPR technique can probe a resistance that is the sum of many resistances in the system, including the resistance of the active material particles, Ohmic resistance from the circuit, and resistance from the electrolyte. The combined value of these later two resistances was consistently found to be between 125Ω and 140Ω from the high frequency intercept of electrochemical impedance spectroscopy measurements, which was always less than 20% of DPR and can be subtracted from the measured resistance for normalizing between measurements. Thus, DPR can be sensitive to the active material particles and the variability due to electrolyte/cell resistance is low. The primary contribution to DPR is from the active material particles, which consists of resistance due to the particle electronic and ionic conductivity as well as activation resistance. Each of these factors can be challenging to measure individually and vary across multiple orders of magnitude with different methods. The DPR approach provides a collective measure that indicates the overall average resistance from an ensemble of the active material particles.
To confirm the relative correlation between DPR and rate capability, DPR measurements were performed on all three LTO materials at 0.5, 1, and 2 vol % LTO loading in electrolyte and the results are shown in
Thus, the total electroactive material area in contact with the current collector is increased, similar to increasing the active material loading or thickness in a conventional coin cell as was the case in the studies mentioned above that measured and predicted decreased resistance under such conditions. These results demonstrated the sensitivity of the DPR technique both to the properties and the amount of electroactive material within the suspension. The DPR measurements and the previous literature discussed above lead us to expect that the measured DPR will decrease with increased active material loading in the electrolyte, decrease with an increase in the ionic and electronic conductivities of the active material, and increase with an increase in particle size.
A major benefit of the DPR method is that the measurement can be made in a convenient way without electrode fabrication, and thus is relatively fast and does not have contributions from other electrode components or the electrode microstructure and connectivity. Additionally, because the suspension is agitated and there are many different particles that are coming into contact with the electrolyte, the measured resistance is an average of contributions from the ensemble of particles in the powder. Thus the technique is representative of the polydisperse particle population of interest, as opposed to single particles selected from within that population. While more materials need to be tested to more generally affirm the DPR technique limits and reliability, these three materials show that a quick DPR measurement provides insights into the relative rate capabilities of the active materials. Most of the DPR measurements took less than 30 minutes total in sample preparation and CP testing.
The terms and expressions that have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the embodiments of the present invention. Thus, it should be understood that although the present invention has been specifically disclosed by specific embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those of ordinary skill in the art, and that such modifications and variations are considered to be within the scope of embodiments of the present invention.
The following exemplary embodiments are provided, the numbering of which is not to be construed as designating levels of importance:
Embodiment 1 provides a method of characterizing a dispersion, comprising electrically applying an excitation signal to the dispersion; and measuring an electrical response elicited by the excitation signal; wherein the dispersion comprises electrically conductive particles and a liquid carrier; and wherein the particles are mechanically perturbed.
Embodiment 2 provides the method of embodiment 1, wherein the excitation comprises a specified voltage or series of voltages applied to the dispersion and wherein the electrical response comprises a measured current.
Embodiment 3 provides the method of any one of embodiments 1-2, wherein the excitation comprises a specified current or series of currents applied to the dispersion and wherein the electrical response comprises a measured voltage.
Embodiment 4 provides the method of any one of embodiments 1-3, wherein perturbing the particles comprises agitating the particles in a vessel.
Embodiment 5 provides the method of any one of embodiments 1-4, wherein perturbing the particles comprises flowing the dispersion including the particles through an electrochemical cell comprising a channel.
Embodiment 6 provides the method of any one of embodiments 1-5, wherein the electrochemical cell comprises: an anode; a cathode; a permeable membrane between the anode and cathode; and a fluid inlet and a fluid outlet.
Embodiment 7 provides the method of any one of embodiments 1-6, wherein at least one of the anode or cathode comprises a precious metal or a nonprecious metal.
Embodiment 8 provides the method of any one of embodiments 1-7, wherein at least one of the anode or the cathode has a serpentine shape.
Embodiment 9 provides the method of any one of embodiments 1-8, wherein perturbing the particles comprises stirring the dispersion including the particles in an electrochemical cell.
Embodiment 10 provides the method of any one of embodiments 1-9, wherein the electrochemical cell comprises an anode; a cathode; and a stir bar.
Embodiment 11 provides the method of any one of embodiments 1-10, further comprising measuring at least two electrical responses to determine a resistance of the dispersion.
Embodiment 12 provides the method of any one of embodiments 1-11, wherein the measuring at least two electrical responses takes about 1 to 120 minutes.
Embodiment 13 provides the method of any one of embodiments 1-12, wherein the liquid carrier comprises an electrolyte.
Embodiment 14 provides the method of any one of embodiments 1-13, wherein the electrolyte is an aqueous electrolyte.
Embodiment 15 provides the method of any one of embodiments 1-14, wherein the electrolyte is aqueous Li2SO4.
Embodiment 16 provides the method of any one of embodiments 1-15, wherein the conductive particles comprise an alkali metal ion conducting material.
Embodiment 17 provides the method of any one of embodiments 1-16, wherein the alkali metal ion conducting material is a lithium-ion conducting material, a sodium-ion conducting material, or mixtures thereof.
Embodiment 18 provides the method of any one of embodiments 1-17, wherein the lithium-ion conducting material LiFePO4 (LFP), Li4Ti5O12 (LTO), LiFeMnPO4, LiCoO2, LiMn2O4, LiNiMnCoO2 (NMC), LiNiCoAlO2, or mixtures thereof.
Embodiment 19 provides the method of any one of embodiments 1-18, wherein the lithium-ion conducting material is LFP or LTO.
Embodiment 20 provides the method of any one of embodiments 1-19, wherein at least 80% of the electrical resistance in the electrochemical cell is due to the conductive particles.
Embodiment 21 provides the method of any one of embodiments 1-20, wherein the conductive particles have a discharge capacity of about 120 mAh/g to about 170 mAh/g.
Embodiment 22 provides the method of any one of embodiments 1-21, wherein the dispersion comprises 0.01 vol % to about 10 vol % of the conductive particles.
Embodiment 23 provides the method of any one of embodiments 1-22, wherein the conductive particles have a BET surface area of about 0.5 m2/g to about 25 m2/g.
Embodiment 24 provides the method of any one of embodiments 1-23, further comprising aging the dispersion for about 1 minute to about 30 days to provide an aged dispersion; and detecting a change in the resistance of the aged dispersion compared to an identical dispersion that is not aged.
Embodiment 25 provides the method of any one of embodiments 1-24, wherein the particles are mechanically perturbed during the measuring.
Embodiment 26 provides a method of characterizing a dispersion, comprising: electrically applying an excitation signal to the dispersion; and measuring an electrical response elicited by the excitation signal; wherein the dispersion comprises conductive particles of a lithium-ion conducting material and an aqueous electrolyte; and wherein the particles are mechanically perturbed by flowing the dispersion including the particles through an electrochemical cell comprising a channel.
Embodiment 27 provides the method claim 26, wherein the lithium-ion conducting material is LFP or LTO.
Embodiment 28 provides the method of any one of embodiments 26-27, wherein the aqueous electrolyte is Li2SO4.
Embodiment 29 provides a system for characterizing a dispersion, comprising: an anode; a cathode; an electrolyte; and a dispersion comprising conductive particles and a liquid carrier.
Embodiment 30 provides the system of embodiment 29, wherein the cathode comprises aluminum.
Embodiment 31 provides the system of any one of embodiments 29-30, wherein the anode comprises lithium.
Embodiment 32 provides the system of any one of embodiments 29-31, wherein the liquid carrier comprises an organic electrolyte.
Embodiment 33 provides the system of any one of embodiments 29-32, wherein the cathode comprises gold.
Embodiment 34 provides the system of any one of embodiments 29-33, wherein the anode comprises platinum.
Embodiment 35 provides the system of any one of embodiments 29-34, wherein at least one of the anode or the cathode has a serpentine shape.
Embodiment 36 provides the system of any one of embodiments 29-35, wherein the liquid carrier is an aqueous electrolyte.
Embodiment 37 provides the system of any one of embodiments 29-36, wherein at least 80% of the electrical resistance in the system is due to the conductive particles.
Embodiment 38 provides the system of any one of embodiments 29-37, wherein the conductive particles themselves undergo an electrochemical reaction.
Embodiment 39 provides the system of any one of embodiments 29-38, wherein the system further comprises a fluid inlet and a fluid outlet.
Embodiment 40 provides the system of any one of embodiments 29-39, wherein the dispersion including the conductive particles flows through the fluid inlet and fluid outlet.
Embodiment 41 provides the system of any one of embodiments 29-40, wherein the conductive particles are mechanically perturbed as they flow through the fluid inlet and fluid outlet.
Embodiment 42 provides the system of any one of embodiments 29-41, wherein the system further comprises a permeable separator between the anode and the cathode.
Embodiment 43 provides the system of any one of embodiments 29-42, wherein the anode and the cathode are disposed between two non-conductive polymer surfaces.
Embodiment 44 provides the system of any one of embodiments 29-43, wherein the polymer comprises polypropylene.
This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 62/540,144 entitled “Dispersion Particle Resistance (DPR) for Characterization and Quality Control of Battery Materials and Related Method Thereof,” filed Aug. 2, 2017, which is incorporated by reference herein in its entirety.
This invention was made with Government support under Grant No. ECCS 1405134 awarded by National Science Foundation. The U.S. Government has certain rights in this invention.
| Number | Date | Country | |
|---|---|---|---|
| 62540144 | Aug 2017 | US |
