Materials according to embodiments relate to solid electrolyte materials for Li solid-state batteries.
In order to reduce the production of carbon dioxide in our society, the demand for rechargeable batteries has drastically increased. A lithium-ion battery has been utilized in these applications due to its highest energy density amongst rechargeable batteries. However, achieving a higher energy density, high ionic conductivity materials with appropriate environmental stability, chemical stability and electrochemical stability has been an ongoing challenge.
Lithium boracite crystals with a general formula of Li4+xB7O12+xXy have been identified as promising Li-ion conductors in an all-solid-state battery, where X is a monovalent or divalent anion. When x=0 and X=Cl (Li4B7O12Cl cubic space group), the conductivity is the highest at room temperature. Partial replacement of the X anion with other X′ is also possible and normally leads to the stabilization of another phase at room temperature and abruptly drops the conductivity near room temperature.
Currently, doping the boron site with Al (Li4B4Al3O12Cl) has been shown to lead to the formation of a glass-ceramic that is stable against Li metal and with a wide electrochemical window between 0 and 6 V vs. Li/Li+ and a Li+ ion transport number of roughly 1.
However, despite the boracite's structural variety, the replacement of the B—O framework with other cationic framework has only been investigated for Al/Ga dopants. Indeed, such replacement of the B—O framework is highly difficult or often impossible, primarily because of the very small ionic radius of the B3+ sites compared to other cations.
Information disclosed in this Background section has already been known to the inventors before achieving the disclosure of the present application or is technical information acquired in the process of achieving the disclosure. Therefore, it may contain information that does not form the prior art that is already known to the public.
The present disclosure focuses on the development of new Li-boracite compositions where the introduction of multi-dopant species into the B3+ site leads to thermodynamically stable Li-boracite phases, previously unknown.
The present disclosure is directed to non-obvious doping strategies of the parent cubic structure Li4B7O12Cl, wherein the tetrahedral BO4 units in the parent lithium chloroboracite, Li4B7O12Cl, are either partially or fully replaced. These non-obvious substituted compounds are formed as the stable primary phase in high crystalline glass-ceramics composed of a Li2O—B2O3-MxOy—LiCl high-dimensional system where M can either be a trivalent specie, or a mixture of bivalent, trivalent, tetravalent or pentavalent species. Accordingly, the compounds of the present disclosure can generally adopt the following chemical form of Li4−xB7−yMyO12−zClw where Li, O, and Cl vacancies are allowed and M can be either a one-way, two-way or three-way combination of the following species: Al3+, Fe3+, B3+, La3+, Y3+, Mo3+, Be2+, Si4+, Cr3+, As3+, Mn2+, V2+, Co2+, Ge2+, Fe2+, Mo4+, Mo6+, As3−, Ti2+, P5+, As0+. Here, 0<x<2, 0<y<6, 0<z<1, 0<w<2 can either satisfy a charge balance mechanism with their respective defect site (B3+, Li+, O2−, or Cl−), or satisfy any combination that maintains the charge neutrality of the overall composition. The concurrent multi-specie doping of the B3+ site and vacancy generation of either Li, O or Cl increases the configurational entropy (i.e. ˜ 100 meV/atom) which subsequently increases the thermodynamic stabilization of non-obvious species on the B3+ site.
The present disclosure demonstrates several approaches to optimize the Li-boracite compositions through the doping of the B3+ sites as to maximize the content of previously unknown elements and cheaper elements.
The present disclosure provides a compound of the formula Li4−xB7−yMyO12−zClw
An embodiment of the present disclosure includes a compound of the formula Li4−xB7−yMyO12−zClw, wherein Li, O, and Cl vacancies are allowed and M is either a one-way, two-way or three-way combination of the following species: Al3+, Fe3+, B3+, La3+, Y3+, Mo3+, Be2+, Si4+, Cr4+, As3+, Mn2+, V2+, Co2+, Ge2+, Fe2+, Mo4+, Mo6+, As3−, Ti2+, P5+, As0+, and wherein 0≤x<2, 0<y<6, 0≤z<1, and 0<w<2 either satisfy a charge balance mechanism with their respective defect site B3+, Li+, O2−, or Cl−, or satisfy any combination that maintains charge neutrality of the compound, and wherein when M comprises Al3+, M is a two-way or three-way combination.
Another embodiment includes the aforementioned compound wherein 0<x<2, 0<y<6, 0<z<1, and 0<w<2.
Another embodiment includes the aforementioned compound wherein the compound is Li8Y4B9Mo(ClO12)2.
Another embodiment includes the aforementioned compound wherein the compound is Li8Y4CrB9(ClO12)2.
Another embodiment includes the aforementioned compound wherein the compound is Li8Y3B8Mo3(ClO12)2.
Another embodiment includes the aforementioned compound wherein M is one, two, or three of Fe3+, La3+, Y3+, Mo3+, Cr4+, As3+, Fe2+, Mo4+, Mo6+, As3−, or As0+ or two or three of Al3+, Fe3+, La3+, Y3+, Mo3+, Cr4+, As3+, Fe2+, Mo4+, Mo6+, As3−, or As0+.
Another embodiment includes the aforementioned compound wherein M is a two-way combination.
Another embodiment includes a glass ceramic composition comprising the aforementioned compound.
Another embodiment includes a lithium ion battery comprising a solid state ionic conductor, wherein the solid state ionic conductor comprises the aforementioned compound.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Example embodiments of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:
The embodiments of the disclosure described herein are example embodiments, and thus, the disclosure is not limited thereto, and may be realized in various other forms. Each of the embodiments provided in the following description is not excluded from being associated with one or more features of another example or another embodiment also provided herein or not provided herein but consistent with the disclosure. For example, even if matters described in a specific example or embodiment are not described in a different example or embodiment thereto, the matters may be understood as being related to or combined with the different example or embodiment, unless otherwise mentioned in descriptions thereof. In addition, it should be understood that all descriptions of principles, aspects, examples, and embodiments of the disclosure are intended to encompass structural and functional equivalents thereof. In addition, these equivalents should be understood as including not only currently well-known equivalents but also equivalents to be developed in the future.
As used herein, expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. For example, the expression, “at least one of a, b and c,” should be understood as including only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b and c.
The present disclosure provides non-obvious doping strategies of the parent cubic structure Li4B7O12Cl, wherein the tetrahedral BO4 units in the parent lithium chloroboracite, Li4B7O12Cl, are either partially or fully replaced. These non-obvious substituted compounds are formed as the stable primary phase in high crystalline glass-ceramics composed of Li2O—B2O3-MxOy—Li—Cl high-dimensional system where M can either be a trivalent specie, or a mixture of bivalent, trivalent, tetravalent or pentavalent species. Accordingly, the compounds of the present disclosure can generally adopt the following chemical form of Li4−xB7−yMyO12−zClw where Li, O, and Cl vacancies are allowed and M can be either a one-way, two-way or three-way combination of the following species: Al3+, Fe3+, B3+, La3+, Y3+, Mo3+, Be2+, Si4+, Cr4+, As3+, Mn2+, V2+, Co2+, Ge2+, Fe2+, Mo4+, Mo6+, As3−, Ti2+, P5+, As0+. Here, 0<x<2, 0<y<6, 0<z<1, 0<w<2 can either satisfy a charge balance mechanism with their respective defect site (B3+, Li+, O2−, or Cl−), or satisfy any combination that maintains the charge neutrality of the overall composition. The concurrent multi-specie doping of the B3+ site and vacancy generation of either Li, O or Cl increases the configurational entropy (i.e. ˜ 110 meV/atom) which subsequently increases the thermodynamic stabilization of non-obvious species on the B3+ site.
Benefits of the concurrent multi-specie doping of the B3+ site and vacancy generation of either Li+, O2−, or Cl− are:
The chemical compositions in the present disclosure are therefore those that minimize the MO4, and BO4 polyhedron strain by increasing the total configurational entropy and maintaining the cubic framework of the parent structure, minimize the total cost of the material, and either maintain or increase the Li-ionic conductivity of the cubic parent structure:
Li4−xB7−yMyO12−zClw
Embodiments of the present disclosure can be made using a standard solid-state method. In this method, precursor powders are combined in a certain ratio depending on the composition of the target material. As one example, precursors may consist of lithium carbonate (Li2CO3), boric oxide (B2O3), lithium chloride (LiCl), and at least one precursor containing an included metal from M, and as another example, precursors may consist of lithium oxide (Li2O), boric oxide, lithium chloride, and at least one precursor containing an included metal from M. Examples of metal precursors include metal oxides, hydroxides, carbonates, and nitrates.
The precursor mixture may be mixed by a method such as ball milling or planetary milling to produce a homogeneous mixture. Mixing may be done with a suitable solvent such as ethanol, isopropanol, ethylene glycol, or acetone to assist with the uniform dispersion of the precursors.
The precursor mixture may then be heat treated to an appropriate temperature for an appropriate period of time to produce a powder with the desired composition and crystal structure. A ceramic composition such as a glass ceramic composition can be prepared including the powder.
Subsequently the powder may be compressed using a hydraulic uniaxial press to form a densely packed pellet. Heat treatment may then be applied at an appropriate temperature for an appropriate period of time to produce a dense pellet which may be used as a solid electrolyte separator in a solid state lithium battery cell.
An embodiment of the aforementioned solid electrolyte separator can be assembled together with a cathode active material layer and an anode active material layer to be used in an embodiment which is a solid state lithium battery comprising a cathode active material layer, an anode active material layer, and a solid electrolyte layer formed between the cathode active material layer and the anode active material layer, wherein the solid electrolyte layer comprises any of the aforementioned materials.
Embodiments will now be illustrated by way of the following examples, which do not limit the embodiments in any way.
With the use of high-throughput density functional theory (DFT) calculations, a wide range of non-obvious potential chemical dopants was selected based on their electronegativity, Shannon's crystal radius, and oxidation state. The initial set of potential chemical dopants includes 45 species selected as: Y3+, Sc3+, Al3+, Be2+, P5+, Mg2+, La3+, As3+, Sr2+, Ti4+, Si2+, Fe3+, Mo3+, Mn2+, Si4+, Ge2+, Cr3+, As0+, Mo6+, V2+, As−, P3+, Co2+, Mo5+, As3−, Mo2+, As−, As2+, Ti2+, Mo4+, B2+, Fe2+, B+, La2+, P4+, As2−, B3−, Se2−, Cr2+, Cr5+, P+, Ge4+, V5+, Cr4+, V4+.
The phase stability of the predicted materials was theoretically calculated by estimating the energy above the linear combination of stable phases in the first principle phase diagram at 0 K, also known as the energy above hull (Ehull). The phase diagrams were constructed using energies calculated using DFT, as well as thermodynamic data from the Materials Project using the Materials Application Programming Interface (API). To assert a threshold value beyond which theoretical compositions in the Li4−xB7−yMyO12−zClw chemical spaces are deemed unstable, the ideal configurational entropy is used (Sideal=−KbTΣipi ln pi), where Kb is the Boltzmann constant, pi is the probability of each state (occupied or unoccupied) and the sum is over all states for each site.
Assume the following dummy species:
The following stoichiometry ranges are disclosed:
In particular,
Assume the following dummy species:
The following stoichiometry ranges are disclosed:
Assume the following dummy species:
The following stoichiometry ranges are disclosed:
Table 2 shows a list of example compositions of the exemplary embodiment with (A) Ehull<100 me V/atom, (B) high Li conductivity, and (C) high moisture stability.
The foregoing is illustrative of exemplary embodiments and is not to be construed as limiting the disclosure. Although a few exemplary embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the above embodiments without materially departing from the disclosure.
This application is based on and claims priority from U.S. Provisional Application No. 63/546,660 filed on Oct. 31, 2023 in the U.S. Patent and Trademark Office, the disclosure of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63546660 | Oct 2023 | US |