Patent Application
20200365889
The present invention relates to the field of technologies for powering portable electronic part, electrical tools, hybrid and electric vehicles, and to storage systems from renewable sources. In particular, the invention relates to lithium ion batteries, and more specifically, to an active compound useful for the manufacture of cathodes in said lithium ion batteries. Still more particularly, the present invention relates to magnesium doped magnesium spinel, cathodic material comprising the same, preparation method and lithium ion batteries comprising thereof.
Lithium-ion batteries have an incomparable combination of high energy density and power; which is why they are the chosen technology for powering portable electronic parts, electrical tools, hybrid and electric vehicles, and to energizing storage systems from renewable sources.
At the present, cobalt lithium oxide, LiCoO2 is the most widely used compound in the manufacture of cathodes for lithium ion batteries; However, due to its high cost, high toxicity, thermal instability and safety problems, its application is limited to small format batteries. In contrast, lithium manganese spinel, LiMn2O4 is the most promising cathode material for large-format lithium-ion batteries. This is due to its diffusion of lithium ions in three dimensions, low cost, low toxicity and abundance of its raw materials. However, LiMn2O4 presents problems such as poor cycling at high temperatures (50° C.), Mn dissolution, electrolyte decomposition at high chemical potential, Jahn-Teller distortion and structural instability; which must be resolved for commercial application.
In order to overcome the different limitations of LiMn2O4, the present invention solves the problem of improving the structural and electrochemical performance: (1) Reducing particle size at a nanometric scale and (2) Doping structures with magnesium ions. For this, the sol-gel synthesis method was used, assisted by ultrasound and raw materials of Li and Mg were used, typical of the Saler de Atacama, Chile.
Among the patent documents related to the invention, it is possible to mention: CN 106207153 which describes a method for rapidly preparing a positive electrode material LiMn2O4 doped with boron, LiB0.04Mn1.96O4, comprising putting first the reagents, namely lithium nitrate, lithium acetate, manganous nitrate, manganese acetate and a boric acid in a melting pot at a molar ratio of Li to Mn to B of 1:1.96:0.04; heating, melting and mixing the reactants uniformly in a preheating oven, put a mixture in a muffle furnace for a flameless combustion reaction in liquid phase, carry out the conservation of the heat for a certain period of time, cooling and grinding a powder product to obtain a spinel electrode material LiB0.04Mn1.96O4, where the positive electrode material for a lithium ion battery has the characteristics of being simple in operation, high in speed of synthesis and low cost, and mass production is easy to implement. The technical problem of an attenuation arises of the capacity of a spinel lithium manganese material in charge or discharge cycles and doping said material with B to repair such deficiency.
US2016329563 discloses an active cathode material coated with manganese oxide of lithium metal with spinel structure doped with fluorine, which can be included in a secondary lithium battery and a method for preparing the same. The cathode active material has improved chemical stability and provides improved charge/discharge characteristics at high temperature (55-60° C.) and high speed. The cathode active material allows lithium ions to pass easily through the coating layer and is chemically stable, and therefore can be used effectively as a cathode active material for a high power lithium secondary battery. The cathode active material has a shell-core structure where the shell is a cover layer of lithium manganese metal oxide with spinel structure doped with fluorine which can be represented by the formula Li1MxMn2−xO4−nFn, where x is 1/(4−z), z is an oxidation number of M, and n is a real number that satisfies 0<n<0.3. The nucleus is a lithium manganese oxide with spinel structure (LMO). The lithium manganese oxide metal shell with spinel structure and core are used in a weight ratio of 1; 20-200 and have a thickness of 1 nm-1 μm.
It focuses on solving the problem of preparing lithium manganese oxide with a spinel structure at low cost, the Jahn-Teller effect, the gradual fading of the capacity of a secondary lithium battery, the destruction of the cathode by the manganese corrosion during the cycles of loading and unloading, the increase in impedance and the decrease in coulombic efficiency by the formation of a layer at the solid-electrolyte interface on the surface of the negative electrode. And for that reason, it proposes the doped material described above.
CN106058205 describes a cathode material composed of doped nickel-lithium cobalt oxide and a method of preparing the same, which comprises: (1) dissolving the manganese ion raw materials in water to prepare a solution A and dissolving a precipitator in the water to prepare a solution B; (2) adding a doped cobalt nickel lithium oxide precursor (LiNixCoyMn−yO2, where M is Mn, Al, Cr, Fe, Mg, Zn or Ti) in solution A, and adding Solution B to solution A while stirring; after completion of the reaction, filtering the mixed solution, collecting solids, and cleaning and drying solids, thereby obtaining solids A; and (3) placing solids A and a lithium source in an oxygen atmosphere furnace to perform high temperature toasting, thereby obtaining products after roasting, namely the cathode material composed of cobalt oxide nickel lithium doped existing in a core structure, whose surface is coated with a spinel layer of lithium manganese. According to the method of preparation, a layer of lithium manganese spinel cathode material is coated on the surface of cobalt nickel lithium oxide to improve the performance and life cycle of a battery cell in use; The spinel of the outermost layer isolates the metallic nickel and avoids contacting the electrolyte directly, so that the stability and safety of the battery can be effectively improved.
The method seeks the production of a material that improves the use of the single cell efficiency process and the life cycle since the separation of the spinel phase from the metallic nickel and the direct contact of the electrolyte can effectively improve the stability and safety of the drums.
CN105932250 describes a method of preparing and applying a structured spinel with metallic doping and a cathodic material containing nickel coated with a fast ionic conductor, comprising: dissolving and mixing organic titanium salt, a cathode material containing nickel and a salt metallic doped obtaining a dispersion liquid; transferring the dispersion liquid to a hydrothermal reaction vessel to carry out a hydrothermal reaction, so that a precursor is obtained; and baking the precursor at high temperature to obtain the cathode material containing nickel from a spinel structured with metallic doping and a layer coated with an ionic conductor, which is dense, uniform and good in stability and ionic conductivity. The nickel-containing cathode material can be used to prepare a lithium-ion battery with excellent performance of number of cycles and rate capability; and it is low cost, easy to operate, friendly to the environment and can be applied to industrial production. The cathode material containing nickel is LiNixMn2−xO4 (0.1<x<0.8) having a spinel structure and/or LiNi1−x−#On having a structure per layer and/or material of cathode enriched in manganese lithium.
It seeks to develop a cathode material with long life and high performance from a simple, low cost and environmentally friendly method.
CN105789568 describes a positive electrode material of a lithium ion battery and a method of preparation thereof, wherein the lithium-rich lithium manganese oxide material doped with a sulfur element has the formula Li1,2MxMn2−xO4−ySy, where 0>x>0.2, 0>y>0.2, and M is Li, Na, K, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, And, Zr, Nb, Mo, Ag, Ce, Sm, Eu, Al, Si, In, Ga, Ge, Sn, Pb, B, Sb, Bi, Se, Te, or combinations thereof. Positive doped ions and sulfur atoms are uniformly doped in the crystal lattice of a lithium manganese oxide material according to a certain ratio using the sol-gel method and a chelator to inhibit the Jahn-Teller effect of the oxide material of manganese lithium. A low specific capacity defect of manganese lithium oxide caused by the fact that the existing lithium manganese oxide spinel can only use a capacity of an area of 4V, the lithium-rich lithium manganese oxide material doped with A sulfur element can use capacities of both, that is, the 4V area and an area of 3V, and the specific discharge capacity of the lithium-rich lithium manganese oxide material doped with sulfur elements is greater than 180 mAh/g. The lithium-rich lithium manganese oxide material doped with the sulfur element can be used as the positive electrode material of small or large lithium ion batteries.
It faces two problems associated with lithium manganese oxide materials: its low capacity (110 mAh/g or similar) and problems of falling capacity. Mainly addressing the attenuation of capacity by dissolution and Jahn-Teller effect caused by manganese, and therefore, proposes doping cationic with lithium ion and doping anionic with sulfur, which expand the area of useful capacity in 3V and 4V.
CN104701522 describes a method of preparing a lithium manganese modified positive material from a lithium ion battery comprising: (1) synthesizing a precursor by adopting a liquid phase temperature difference method to obtain doped manganese carbonate precursor powder with aluminum, where the carbonate is preferably lithium carbonate, the manganese source compound, preferably manganese sulfate, and the aluminum salt, preferably aluminum nitrate, are in a molar ratio of 39:1 to 9:1 to 0.2 mol/L, an aqueous solution 0.2 mol/L to 0.5 mol/L and the temperature of the two aqueous solutions are controlled within the range of 0 to 10° C. and are mixed rapidly with 10° C./min at 50-80° C., after matured for 30 minutes, filtered and dried at 40° C. to obtain a precursor powder of manganese carbonate doped aluminum; (2) calcination of the precursor manganese carbonate powder obtained during 2-5 hours under the temperature of 600-800° C., in order to obtain a manganese oxide powder doped with aluminum with a spherical structure of ionic holes and being a particle diameter 1-3 microns where calcination occurs at a temperature between 600-800° C. for 2 to 5 hours; (3) uniformly mixing the powder carbonate-manganese precursor doped with aluminum and lithium carbonate according to the ratio of (1 to 1)-(1.05 to 1), keeping temperature for 20 hours under a temperature of 900° C. for 20 hours, cooling, grinding, repeating the process from baking until grinding for 3 times, to obtain a positive material sample with modified spinel structure of lithium manganese with a particle diameter of 1-2 microns. The method uses low cost and easy to obtain raw materials, the microstructure is regular and uniform, the doping effect is good and the modified lithium manganate prepared is evident in the loading and unloading performances and good in circularity. Solve the technical problem of LiMn2O4 capacity loss.
CN104538625 discloses a method of preparing ion lithium battery positive electrode material of doped lithium manganese dioxide with high magnification and excellent cyclization performance comprising placing the reagents of lithium nitrate, manganese acetate and copper acetate in a melting pot, adding an appropriate amount of nitric acid, burning in a muffle furnace and preserving the heat, thus obtaining a spinel LiCu0.05Mn1.95O4. The positive electrode material of lithium-ion battery LiCu0.05Mn1.95O4. It has characteristics of simplicity of operation, fast synthesis speed, low cost and scale production, being easy to achieve.
The main advantage is a rapid combustion synthesis reaction and within a short period of time to achieve complete crystals, products of particular small size, which leads to a production process of LiMn2O4 conductive spinel.
US2015089797 describes a doped spinel of the following formula: Li1±wMe1vMe2x−vMn2−x−yTiyO4−zFz where, 0≤w<1, 0.3<x≤0.7, 0.3≤v<0.7, x>v, 0.0001≤y≤0.35 and 0.0001≤z≤0.3. Me1 is a metal selected from a group of elements consisting of Cr, Fe, Co, Ni, Cu and Zn. Me2 is a metal selected from a group of elements consisting of Ni, Fe, Co, Mg, Cr, V, Ru, Mg, Al, Zn, Cu, Cd, Ag, Y, Se, Ga, In, As, Sb, Pt, Au and B. It also provides a lithium ion battery comprising said doped spinel and provides a doped spinel or a high voltage doped spinel that can be cycled stably with more than one lithium per unit.
CN104112856 describes a pre-combustion treatment comprising the synthesis of a lithium manganese spinel cathode material doped with metallic aluminum, comprising: mixing lithium carbonate, electrolytic manganese dioxide and hydrated aluminum nitrate, preferably nitrate aluminum hexahydrate in a ratio of Li2CO3:EMO:Al(NO3)3.9H2O from 1.0 to 1.05:1.7 to 2.0:0 to 0.3 and where preferably the content of manganese dioxide is greater than 91%, and Li2CO3 and Al(NO3)3.9H2O are analytical grade; taking absolute ethanol as dispersant, subjecting the mixture to grinding and drying to obtain a reaction precursor; Preheating the precursor for 4 to 6 hours at a temperature of 400 to 500° C. at a rate of 5-10° C./min, burning for 6 to 36 hours at a temperature of 750° C. at a rate of 5-10° C./min, placing the precursor in a tubular oven to carry out an annealing treatment in an atmosphere of oxygen gas at 600° C. where it is maintained for 6 hours, cooling naturally to room temperature, crushing and sieving to obtain the cathodic material of a Lithium-ion battery with a mesh size of 200-325. The prepared cathode material has the advantages of high capacity and good stability in cycling. Compared to the prior art, the technology is simple and feasible, the cost is low and the method is advantageously applied to industrial production.
Providing lower cost of cathode material raw materials for lithium ion batteries to improve electrochemical stability of materials lithium manganese oxide spinel type, so that they increase the capacity, stability in cycling; it also improves the high temperature solid phase synthesis of lithium magnesium oxide cathode material doped with aluminum.
CN102569781 discloses a high-voltage lithium-ion battery cathode material and its method of preparation, wherein said high-voltage lithium-ion battery cathode material is a solid solution material with a stratiform and spinel composite structure and formula LixNi0.25−zMn0.75−zM2zOy, where M is one or two of doped metals selected from Co, Al, Cr, Mn and Ga, 2>x>0, 3>y≥2 and 0.25>z>0. The cathodic material has the stratiform composite structure and spinel, maintains the high specific capacity of a solid solution material based on manganese, improves the stability of cycling and the thermal stability of the material. The impedance of the cathode material is reduced by doping, so that the thermal stability of the material is further improved, and the heat release is reduced to improve the overall electrochemical performance of the material. The material preparation process has high control capacity, the manufacturing cost is low and the manufacturing process has high reproducibility and high batch stability, it facilitates the production management of high voltage materials and high specific capacity.
It provides a high-voltage lithium-ion battery cathode material comprising a solid solution of high specific capacity that improves cycling performance and thermal stability of the material, reduces production costs, improves production stability in batches.
CN102306767 relates to a method for preparing spinel-type lithium manganese that serves as the cathode material of a lithium-ion battery comprising: 1) mixing manganese oxide selected from electrolyte or chemical MnO2, Mn3O4 or MnOOH, a lithium source material selected from LiOH, Li2CO3 or LiNO3 and a metal oxide as dopant element, where the selected metal is Li, Al, Cr, Co, Mg, Ca, Ni, Zn, or a mixture thereof; and 2) uniformly mixing the mixture obtained in step 1), and subjecting it to a continuous sintering gradient inside a high temperature sintering furnace (sintering steps: sintering at a temperature of between 1,000 and 1,200° C.) for 3 to 5 hours in the first stage, sintering at a temperature between 800 and 900° C. for 4 to 6 hours in the second stage and sintering at a temperature between 500 and 700° C. for 5 to 8 hours in the third stage), introducing compressed air simultaneously. Next, the sintered product is subjected to natural cooling, trituration and selection process to obtain the cathodic material. The procedure is simple; the crystallinity and the surface of the cathodic material are controlled through ultra-high temperature sintering to reduce the rate of manganese dissolution; while the process of sintering at low temperatures controls or eliminates oxygen deficiencies.
It focuses on improving the crystalline structure of lithium manganese oxide and therefore its poor cycling stability due to manganese dissolution factors and oxygen deficiencies, and therefore, it reduces and eliminates or controls the oxygen deficiencies in the crystalline structure of the manganese spinel. The doping of the crystalline structure of lithium manganese oxide with metallic elements of Mg, Al or Cr is carried out to improve stability during cycling.
CN102122715 describes a lithium manganese oxide doped with indium comprising a spinel of manganese lithium and a metal element of indium, which is 0.02 to 5% of the mass of the lithium manganese spinel doped with indium and its method of preparation comprising: uniformly mixing a lithium source substance and manganese dioxide powder according to the mole ratio of Li to Mn which is (0.50-0.65) to 1 and adding source substance of powdered indium simultaneously; placing the mixture in an air or oxidation environment whose temperature is between 600 and 1,000° C.; then uniformly mixing the mixture and baking for 8 to 32 hours; Cooling and sifting to obtain lithium manganese oxide doped with indium. Wherein said metal element of indium is present within the lithium manganate doped with indium in the form of indium trioxide and indium oxide; which are formed on the spinel-type lithium manganese surface or on the micropores of the surface or penetrating the internal structure to form a compound of formula LiMn2−xInxO4, where 0<x<0.1. Where the lithium source material is a mixture of one or more of lithium carbonate, lithium hydroxide and lithium nitrate. The lithium manganese oxide doped with indium can be used as a positive electrode material of a small lithium-ion battery or a lithium-ion power battery and has the advantages of high cycling stability, strong charge holding capacity and low loss of storage capacity.
Providing good cycling stability, strong load holding capacity, and low loss of lithium storage capacity; In addition, the application of lithium manganese oxide doped with indium in lithium ion batteries, provides a process of preparation of low energy consumption to obtain a product of good quality.
CN104752711 is referring a method of preparing a LiMn2O4 cathode material doped with nickel, which has a high multiplicative power and efficiency in the cycling of a lithium ion battery, which comprises: putting for the first time in a preheated constant temperature muffle furnace, reagents including lithium acetate, manganese acetate and nickel acetate in a melting pot, and then baking in the muffle furnace for the second time to obtain a LiNi0.05Mn1.95O4 spinel type electrode material. The method of preparing the material for the LiNi0.05Mn1.95O4 spinel type cathode, of lithium-ion battery, prepared by the invention has the characteristics of being simple to operate, fast in synthesis speed, low cost and easy to produce on a large scale; and in addition, the cycling time of the LiNi0.05Mn1.95O4 spinel-type cathode material is increased as cathode material.
It provides a method of preparation of broad efficiency, reduces manufacturing costs, allows a fast and efficient preparation and that improves the performance of the lithium ion battery, as well as the capacity retention speed during cycling of the LiNi0.05Mn1.95O4 spinel doped with nickel.
U.S. Pat. No. 5,928,622 is referring a high capacity LiMn2O4 compound used for a nonaqueous electrolyte lithium ion battery, more particularly, to a method for preparing LiMn2O4 intercalated compound doped with Li and Co ions, which comprises the following stages of: synthesizing spinel type LiMn2O4 powder; dissolving and treating the LiMn2O4 powder in the solution to adsorbing Li and Co ions; and a heating treatment of said LiMn2O4 to obtain LiMn2O4 doped with Li and Co.
It addresses the reduction in discharge capacity resulting from repeated charges and discharges in a lithium ion battery LiMn2O4 due to the dissolution of Mn+3 ion in LiMn2O4 and the structural instability of the Jahn-Teller transition.
U.S. Pat. No. 6,274,278 is referring a process for preparing an oxide of lithium manganese compound of spinel type represented by the formula LixMn(2−y)My1By2O4 in which M represents at least one element selected from Al, Cr, Fe, Ni, Co, Ga and Mg; 0.9<x<1.1; y=y1+y2, where 0.002<y<0.5, 0<y1<0.5 and 0.002<y2<0.1 or the formula LixMn(2−y)MyO4, which is the same that the previous formula except that y2 is 0. In the first formula M and x are each as previously defined and 0.002<y<0.5; and an active cathode material for a rechargeable lithium ion battery comprising spinel-type manganese lithium oxide having improved charge/discharge characteristics produced by the method described above. The composite oxide thus produced is an improved novelty particularly in a charge/discharge cycle characterized at a high ambient temperature (50° C. or higher), and therefore it is very useful from the point of view of the Industry.
Providing a cathode material for lithium ion batteries or secondary battery of 4 V that derives from the LiMn2O4 spinel, where part of the manganese is replaced by a metallic element that has the effect of maintaining the capacity of a sufficiently constant battery during a loading/unloading cycle without causing a significant loss in capacity.
U.S. Pat. No. 5,316,877 teaches an electrochemical cell comprising a cell container and a cathode located in said container, wherein the cathode comprises at least one electrochemically active compound of lithium, manganese and oxygen, having a spinel-like structure and formula Li1DxMn2−xO4+δ, where it is true that 0≤x<0.33; 0≤δ<0.5, and the values of x and δ are such that the oxidation state N of the manganese cation is 3.5<N<4.0; D is a mono- or multi-valent metal cation. Particularly, D may be a metal catalyst other than L, such as a divalent metal cation such as Mg. It may also be a monovalent metal cation other than L, such as Ag or a trivalent metal cation such as Co3+; and b is the oxidation state of D. An electrolyte is also located in the container of the cell. The cell, electrolyte and cathode container are arranged to allow the application of a charge potential on the cell which causes the cathode lithium to form at least part of the anode in the cell compartment while the electrolytes join the cathode electrochemically to the anode and isolates the same.
U.S. Pat. No. 6,017,654A is referring to crystalline lithiated transition metal oxide materials having a rhombohedral structure and including divalent cations selected and added in amounts so that all or a portion of the divalent cations occupy sites in the transition metal layers within the crystalline lattice. Said transition metal oxides are useful as cathode materials in secondary cells of lithium ion and include but are not limited to Li1+xN1−yMyNxO2(1+X) and Ni1−yMyNxOp, where M is a transition metal selected from titanium, vanadium, chromium, manganese, iron, cobalt and aluminum, and N is a group II element selected from magnesium, calcium, strontium, barium and zinc. The materials have improved cyclability and high voltage capacity as cathodes in secondary cells of lithium ion. The production process of the material is also disclosed.
CN104253267 relates to lithium titanate material Li4MxTiyO12 spinel type coated with carbon used as cathode material of lithium ion battery, a production method and an application thereof. The cathode material is a Li4MxTiyO12 spinel type or a single or multiple metal Li4MxTiyO12 compound doped with a metallic element. Its synthesis includes: mixing an organic solution of titanium and a liquid salt of lithium to prepare a sol; maturing such sol to obtain a precursor of lithium titanate gel; calcining the predecessor of such gel to obtain the nano-sized lithium titanate spinel material. Alternatively, it comprises: dispersing such lithium titanate prepared in an organic solution of carbon source, removing the solution and calcining to obtain a lithium titanate spinel/nanometer-sized spinel carbon composite. Compared to the lithium titanate Li4Ti5O12 prepared by a conventional method, the lithium titanate spinel material has a better multiplicative power characteristic, when such lithium titanate material is used as the battery cathode of lithium ion, the power output of the cell can obviously increase. Despite the efforts, there is still a need for a spinel that allows the manufacture of lithium ion battery with better electrochemical and structural properties at high temperatures, which decrease the dissolution of Mn at high potentials and the Jahn-Teller distortion of the spinel. That is, a spinel that allows the manufacture of positive electrodes for lithium ion batteries with better structural and electrochemical performance.
The present invention relates to the field of technologies for powering portable electronic parts, power tools, hybrid and electric vehicles, and energy storage systems from renewable sources. In particular, the invention relates to lithium ion batteries, and more specifically, to a compound useful for the manufacture of cathodes in said lithium ion batteries. Still more particularly, the invention relates to a manganese spinel doped with magnesium, cathodic material comprising the same, preparation method and lithium ion batteries comprising thereof.
The present invention solves the problem of improving the structural and electrochemical performance of the spinel, reducing the particle size on a nanometric scale and doping the structure with magnesium ions. The spinel is prepared by the sol-gel synthesis method assisted by ultrasound and raw materials of Li and Mg were used, typical of the Salar de Atacama, Chile.
The electrochemical performance of the doped spinel of the present invention was evaluated as well as its structural, physical and chemical properties of the material of the invention (Mg-doped Mn spinel, (LiMgxMn2−xO4, 0.02<x<0.1) and was compared to a pure spinel and a commercial spinel showed that the spinel doped with Mg, presents better electrochemical performance and better structural properties compared to pure and commercial spinel.
A prototype of a 10 Ah capacity lithium-ion battery module was also developed, consisting of individual pouch-type cells, composed of double coating cathodes of LiMg0.05Mn1.95O4, anodes of single and double graphite coating, a polymeric separator and LiPF6 aprotic electrolyte.
The spinel doped with Mg was prepared from the following sol-gel synthesis method assisted by ultrasound, which allowed to obtain active materials with homogeneous morphology and particle size in nanometric scale. The doping with Mg in the manganese spinel increased the average oxidation state of the manganese, increasing the electrical conductivity of the cathodic material without modifying the symmetry of the crystalline cell.
The present invention is related to a manganese spinel doped with magnesium (LiMg0.05Mn1.95O4), cathodic material comprising the same, method of preparation and use in lithium ion batteries.
The evaluation of the electrochemical performance of a Mg-doped Mn spinel, LiMg0.05Mn1.95O4, was performed on a laboratory scale in coin 2032-type cells, composed of a positive electrode of LiMg0.05Mn1.95O4, a metallic lithium negative electrode, a polymeric separator and an aprotic electrolyte of LiPF6. The structural and electrochemical properties of the material of the invention (Mg-doped Mn spinel, (LiMg0.05Mn1.95O4) were compared with a pure spinel and a commercial spinel. The results showed that the spinel doped with Mg, presents better electrochemical performance and better structural properties compared to pure spinel and commercial spinel.
Based on the promising electrochemical results obtained in the coin type cells, a prototype of a 10 Ah capacity lithium ion battery module was developed, consisting of individual pouch cells, composed of single and double LiMg0.05Mn1.95O4 coated cathodes, double-coated graphite anodes, a polymeric separator and aprotic electrolyte of LiPF6. At the present time, commercial solutions for the LiMn2O4 are not known with characteristics similar to those proposed in the present invention.
The ultrasound-assisted sol-gel synthesis method that was used to prepare the spinel doped with Mg, proved to be efficient for the preparation of active materials, applied to lithium ion batteries, with homogeneous morphology and particle size in nanometric scale. The doping with Mg in the manganese spinel—without consent with any theory, would have increased the average oxidation state of the manganese, which increased the electrical conductivity of the cathode material, and on the other hand, does not modify the symmetry of the crystalline cell. Manganese spinel doped with magnesium proved to possess physical, chemical and electrochemical properties superior to commercial spinel and pure spinel. The electrochemical performance of manganese spinel doped with Mg, especially during cycling tests, it can be significantly improved with the optimization of a synthesis method and a heating treatment.
Pure spinel (LiMnO4) and spinel doped with Mg (LiMg0.05Mn1.95O4) were synthesized by means of the sol-gel method assisted by ultrasound. For the synthesis of manganese spine's, lithium and manganese raw materials were used: Li2CO3 (battery grade >99.5%, Rockwood—Chile) and Mn(CH3COO)2 (>99%, Sigma Aldrich), respectively; in addition to the addition of Mg(OH)2 (≥99%, Fluka Analytical) for the spinel doped with magnesium.
For the synthesis, two aqueous solutions were prepared. The first solution corresponds to the dissolution in stoichiometric quantities of the precursors of metal ions, Li2CO3 and Mn(CH3COO)2 for the pure spinel and Li2CO3, Mn(CH3COO)2 and Mg(OH)2 for the spinel doped with Mg, in distilled water at room temperature and the second solution corresponds to the dissolution of the organic precursors ethylene glycol and citric acid in distilled water. Both aqueous solutions were mixed under continuous agitation. The pH of the resulting solution was adjusted between a range of 6 to 6.5 by adding ammonium hydroxide, thereby obtaining a “sol”. The “sol” was subjected to sonication for 2.5 hours using an ultrasound bath and then heated to 80° C. to evaporate the water content and obtain the “gel”. Subsequently, the “gel” was dried in a muffle at 170° C. for 12 h. The “dry gel” or synthesis precursor obtained was ground in an agate mortar and sieved for subsequent Thermogravimetric (TG) analysis. Using this technique, the optimal time/temperature programming for the heat treatment of the synthesis method was determined. Finally, the powders of the synthesis precursor were calcined in air atmosphere at 500° C. for 4 h and at 750° C. for 12 h to finally obtain the pure manganese spinel (LiMn2O4) and the spinel doped with magnesium, (LiMg0.05Mn1.95O4).
For the manufacture of the cathodic coatings, it was prepared a suspension consisting of a mixture of 90% by weight of cathodic active material [pure manganese spinel (LiMn2O4) or spinel doped with Mg (LiMg0.05Mn1.95O4) or commercial spinel (Li1.16Mn1.84O3.996S0.004), 5% by weight of carbon black as a conductive additive and 5% by weight of PVdF (polyvinylidene difluoro) as a binder in NMP solution (n-methyl pyrrolidone). The mixing process of the coating suspension was carried out in a paddle mixer under static vacuum conditions (=0.1 atm) to minimize water contamination in the suspension. The different constituents of the positive electrode, cathodic active material, conductive additive and binder were added one by one to minimize agglomeration and achieve homogeneity of the suspension.
The suspension obtained was deposited on Al paper, as a current collector, to perform the cathodic coating and then subjected to a pre-drying process in the presence of air for 12 hours, to fix the cathode cover on the current collector.
Next, a calendering of the cathodic coating was carried out to improve the adhesion of the cathodic suspension on the aluminum foil and establish the porosity of the coating according to the following expression:
ϕ=1−Vh/Vs
wherein VI, is the volume of the wet cathodic coating and Vs is the volume of the dry cathodic coating. Finally, the cathodic coating was subjected to a final vacuum drying process for 12 h, in order to eliminate all the water content. The completely dry cathodes were cut in circles with a diameter of 9/16″ (1.43 cm) Table 1 details the characteristics of the prepared cathodes.
The physical and chemical properties of the synthesized cathode materials and commercial material were determined by applying the following characterization techniques:
Electrochemical Measurements
To evaluate the electrochemical performance of the cathode materials, CR2032 coin-type lithium ion cells were manufactured. The coin cells (
Comparative analysis between the commercial spinel and spinel doped with Mg of the invention, elemental chemical analysis and bulk density
The stoichiometries of the commercial, pure, magnesium-doped manganese spinels of the invention were elucidated from the elemental compositions provided by the EDS measurements, as shown in Table 3.
The average oxidation state of the manganese in each oxide with spinel structure, whether commercial or pure or doped with magnesium (Table 3), was determined by the charge balance of its different constituent elements based on the electroneutrality of each molecule. spinel oxide,
The elemental quantification of the commercial spinel (Table 3) showed the presence of sulfur in small amounts and an excess in the concentration of lithium. The commercial spinel has a co-doped crystalline structure; on the one hand, cationic doping with lithium ions that partially replace the manganese content, allowing to obtain as a result—without consent with any theory, an increase in the average oxidation state, high electrical conductivity and greater load capacity of the active material. On the other hand, anodic doping with sulfur ions that partially replace the oxygen concentration. Without consenting to any theory, the addition of sulfur ions would improve the structural stability of the spinel and reduce/eliminate the dissolution of Mn at high potentials, because sulfur would form stronger Mn—S bonds in comparison to those formed by oxygen O—S. An exact stoichiometric ratio of 1:2:4 for Li:Mn:O was evidenced for the pure spinel (Table 3) synthesized by the sol-gel method assisted by ultrasound.
Regarding manganese spinel doped with Mg, the elemental analysis (Table 3) showed the presence of a spinel with Mg cationic doping. Without consenting to any theory, the small amounts of magnesium ions would replace partially the manganese content in the structure of the spinel; which would result in a higher average oxidation state compared to pure spinel, high electrical conductivity and greater structural stability. The EDS compositional analysis, by elementary mapping using false color images (
Particle Size and Morphology
Crystal Structure
As a result of the refinement of the X-ray patterns, by means of the Rietveld method, it was determined that the three spinels have a crystalline structure with cubic symmetry and spatial group Fd3m. In addition, it was verified that the co-doping with sulfur-lithium, for the commercial spinel, and the doping of magnesium, for the doped spinel, do not modify the crystalline structure. Regarding the cell parameters, it was evidenced that the pure spinel has a smaller cell dimension compared to the commercial spinel and the spinel doped with Mg, which have a similar cell dimension. The small increase in length of the commercial spinel cell parameter, co-doped with sulfur and lithium, compared to pure spinel, is attributed to the incorporation of the sulfur ion (S2−) in the crystalline structure of the manganese spinel; this is due to the fact that the sulfide ion has a greater ion radius with respect to the oxygen ion (O2−), besides forming stronger bonds with manganese that improve the structural stability of the manganese spinel. In contrast, the increase in the length of the spinel cell parameter doped with Mg is attributed to the substitution of the Mn3 ion by the Mg2+ ion, and that it has a greater ion radius than the Mn4+ ion. The monovalent oxidation state of the Mg2+ ion remains unchanged during the process of intercalation and de-interleaving of the lithium ion in a way that reduces the corresponding effects of expansion and contraction of the crystalline cell, improving the structural stability of the manganese spinel during cycling at temperatures in environmental and high conditions.
Table 5 shows the data obtained from the characterization of the physical and chemical properties of manganese spinels: commercial spinel Li1.15Mn1.84O3.996O0.004, pure spinel and spinel doped with Mg (LiMg0.05Mn1.95O4).
Cycling and Impedance Tests
After the 100 cycles of loading/unloading the coin cells assembled with the cathodes of the commercial manganese spinel and the synthesized spinel of the invention, the processing of the cycling data, as shown in
The impedance value of the cathode of the invention, after 100 cycles was 49% lower compared to the commercial cathode of manganese spinet. This difference should be due to no theory, low particle size, high chemical reactivity and high average oxidation state of manganese, which increases the electrical conductivity of the material and is attributed to the incorporation of magnesium ions in the structure of the manganese spinet.
Table 6 shows the results obtained from the stereochemical measurements for the commercial spinet and the synthesized spinet.
For the design of the lithium ion battery module with the cathodic material developed based on the material of the present invention, a program developed in Excel software, called BatPac v2.2, was used. This tool provides necessary data for the design and dimensioning of the electrodes, cells, modules and packs that make up a complete lithium ion battery, this according to the energy and power criteria required by the designer.
Table 7 shows the design criteria of the lithium ion battery module used in the BatPac v2.2 tool.
1EV = Electric vehicles
2SOC = State of Charge
In this way, referring to the design criteria (Table 7) and the initial experimental parameters required, the Excel tool was executed with the following specifications:
The data obtained from the simulation show that to manufacture a lithium ion pouch cell, with an LMO-Mg/G capacity of 4 Ah, 23 double-coated electrodes (12 positive electrodes and 1 negative electrodes) and 2 electrodes are required. Simple negative coating. The arrangement of the electrodes is alternately, starting and ending with a negative electrode of simple coating.
A better detail of the parallel connection of the cells can be seen in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2221-2017 | Sep 2017 | CL | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CL2018/050076 | 8/29/2018 | WO | 00 |
