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US-20260128320-A1 - CATHODE ACTIVE MATERIAL COATED WITH LITHIUM BORATE DOPED LITHIUM CARBONATE AND SULFIDE ALL-SOLID-STATE BATTERY COMPRISING SAME

US20260128320A1US 20260128320 A1US20260128320 A1US 20260128320A1US-20260128320-A1

Abstract

Disclosed are cathode active material (CAM) coated with a lithium carbonate doped with lithium borate with a formula of Li 2+x C 1−x B x O 3 wherein 0<x<0.5 and a preparation method therefor. Also disclosed is a cathode layer comprising the coated CAM in the form of particles. In one embodiment, an all-solid-state battery comprising the cathode layer exhibits improved stability and cycling performance.

Inventors

  • Minh Nguyen
  • Fang Hao
  • Joanna Burdynska

Assignees

  • FACTORIAL INC.

Dates

Publication Date
20260507
Application Date
20231205

Claims (20)

  1. 1 - 28 . (canceled)
  2. 29 . A coated cathode active material comprising: particles of a cathode active material (CAM); and a coating coated on surface of the particles, wherein the coating comprises a lithium carbonate doped with lithium borate (LCBO) having a formula of Li 2+x C 1−x B x O 3 , wherein 0<x≤0.3, and wherein the coating has a thickness in a range from 0.5 to 20 nm, and the LCBO is formed between lithium carbonate on surface of the particles of the CAM and lithium borate or a precursor of lithium borate, wherein the coating comprising the LCBO is prepared by: a) applying to the particles of the CAM with a coating solution comprising a solvent, a lithium precursor and a borate precursor, leading to particles of the CAM coated with the lithium precursor and the borate precursor after removal of the solvent; and b) annealing the particles of the CAM coated with the lithium precursor and the borate precursor, wherein lithium carbonate on surface of the particles of the CAM, the lithium precursor and the borate precursor are converted into the LCBO, thereby obtaining particles of the CAM coated with the LCBO.
  3. 30 . The coated cathode active material of claim 29 , wherein the solvent for preparing the coating solution is nonaqueous and selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, t-butanol, and mixtures thereof.
  4. 31 . The coated cathode active material of claim 29 , wherein the particles have an average diameter of 1-15 μm.
  5. 32 . The coated cathode active material of claim 29 , wherein the CAM is selected from the group consisting of Li x MO 2 , Li x Ni 1-y-z Co y M1 z O 2 and Li x Ni 1-y-z Mn y M2 z O 2 , wherein M is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, wherein M1 is at least one selected from the group consisting of Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, wherein M2 is at least one selected from the group consisting of Co, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, and rare earth elements, and wherein 0.95≤x≤1.1, 1-y-z>0, 0<y≤0.5, 0≤z≤0.5.
  6. 33 . The coated active material of claim 29 , wherein the CAM is surface-doped by a doping element which is at least one selected from the group consisting of Ni, Co, Mn, Al, B, Fe, Mg, Ca, Sr, Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Rh, Pd, Cu, Zn, Cd, Ga, In, Sn, Si, Ge, S, P, and rare earth elements.
  7. 34 . The coated active material of claim 29 , wherein the CAM contains element Ni with a molar fraction of at least 70% in all metal elements other than lithium.
  8. 35 . The coated active material of claim 29 , wherein the cathode active material is polycrystalline particles or single crystalline particles.
  9. 36 . The coated cathode active material of claim 29 , wherein a concentration of lithium carbonate in the coating decreases from a surface of the particles of the CAM to an exterior of the coating, and wherein a concentration of lithium borate decreases from the exterior surface of the coating to the surface of the particles of the CAM.
  10. 37 . The coated cathode active material of claim 29 , wherein the LCBO has a formula selected from the group consisting of Li 2.05 C 0.95 B 0.05 O 3 , Li 2.10 C 0.90 B 0.10 O 3 , Li 2.15 C 0.85 B 0.15 O 3 , Li 2.25 C 0.75 B 0.25 O 3 , and Li 2.30 C 0.70 B 0.30 O 3 .
  11. 38 . A method for preparing the coated cathode active material of claim 29 , comprising: a) determining weight percentage of lithium carbonate on surface of particles of cathode active material; b) preparing a coating solution comprising a solvent, a lithium precursor and a borate precursor, wherein the amounts of the lithium precursor and borate precursor are calculated based on the formula Li 2+x C 1−x B x O 3 , wherein 0<x≤0.3, and the weight percentage of lithium carbonate from step a); c) applying the coating solution to the particles of the cathode active material, leading to particles of the CAM coated with the lithium precursor and the borate precursor after removal of the solvent; and d) annealing the particles of the CAM coated with the lithium precursor and the borate precursor, wherein the lithium carbonate on surface of particles of cathode active material, the lithium precursor and the borate precursor are converted into lithium carbonate doped with lithium borate (LCBO) thereby obtaining the coated cathode active material.
  12. 39 . The method of claim 38 , wherein the solvent for preparing the coating solution is nonaqueous and selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, t-butanol, and mixtures thereof.
  13. 40 . The method of claim 38 , wherein the coating solution is annealed in a range from 150 to 600° C. for a duration in a range from 0.5 to 3 hr under an oxygen atmosphere.
  14. 41 . The method of claim 38 , wherein applying the coating solution comprises spray coating the coating solution onto surface of the cathode active material or mixing the particles of the cathode active material with the coating solution.
  15. 42 . A cathode layer comprising the coated cathode active material of claim 29 .
  16. 43 . The cathode layer of claim 42 , further comprising an electrically conductive material selected from carbon fiber, vapor growth carbon fiber, carbon nanotube, graphite fiber, and mixtures thereof.
  17. 44 . The cathode layer of claim 42 , further comprising a sulfur-containing inorganic electrolyte selected from the group consisting of Li 2 S—P 2 S 5 , Li 2 S—P 2 S 5 -LiHa, Li 2 S—P 2 S 5 —P 2 O 5 , Li 2 S—Li 3 PO 4 —P 2 S 5 , Li 3 PS 4 , Li 4 P 2 S 6 , Li 10 GeP 2 S 12 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , Li 7-x PS 6-x Ha x , and mixtures thereof wherein “Ha” is one or more halogen elements, and 0.2<x≤1.
  18. 45 . An all-solid-state battery (ASSB) comprising the cathode layer of claim 42 .
  19. 46 . The ASSB of claim 45 , further comprising an inorganic solid electrolyte layer, wherein the inorganic solid electrolyte layer comprises a sulfur-containing inorganic electrolyte selected from the group consisting of Li 2 S—P 2 S 5 , Li 2 S—P 2 S 5 -LiHa, Li 2 S—P 2 S 5 —P 2 O 5 , Li 2 S—Li 3 PO 4 —P 2 S 5 , Li 3 PS 4 , Li 4 P 2 S 6 , Li 10 GeP 2 S 12 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 7 P 3 S 11 , Li 3.25 P 0.95 S 4 , Li 7-x PS 6-x Ha x , and mixtures thereof, wherein “Ha” is one or more halogen elements, and 0.2<x<1.
  20. 47 . The ASSB of claim 45 , wherein when the ASSB is charged and discharged for 20 cycles at 45° C. from 2.8V to 4.25V at 0.1 C for cycles 1 and 2, 0.33 C for cycles 3 and 4, 1.0 C for cycle 5, and 0.5 C for cycles 6 to 20, the ASSB exhibits a 20 th cycle life retention rate of at least 98%, wherein each cycle charges to 4.25V and discharges to 2.8V, and wherein the 20 th cycle life retention rate is the ratio of the discharge specific capacity at the 20 th cycle to the initial discharge specific capacity at 0.5 C at 45° C.

Description

CROSS-REFERENCE This application claims the priority of U.S. application Ser. No. 18/194,145 filed on Mar. 31, 2023 and claims the benefit of U.S. Appl. No. 63/386,183 filed on Dec. 6, 2022, the entire contents of which are hereby incorporated by reference in its entirety. FIELD The present disclosure relates to cathode active material coated with lithium carbonate borate and a sulfide-based all-solid-state battery (ASSB) comprising the same. BACKGROUND All-solid-state batteries (ASSBs) are considered as promising candidates for future energy storage devices as they may enable the use of lithium metal as anode material and lead to higher specific energies compared to conventional lithium-ion batteries based on organic liquid electrolytes. Sulfide solid electrolyte (SE) materials comprise element the sulfur in the −2 oxidation state (S−2) and have narrow intrinsic electrochemical windows. Thiophosphate-based solid electrolytes (SEs) contain elements phosphorus (P) and sulfur (S) and are particularly promising because of their high ionic conductivities, good mechanical compatibility, and relatively low costs. The passivation of SEs is necessary for the reversible operation of all-solid-state batteries. In particular, the adaptation of conventional high-capacity cathode active materials (CAMs) such as lithium metal oxide CAMs (ex. LiNi0.88Co0.09Al0.03O2—NCA88) to ASSBs suffer from interfacial resistances. The interfacial resistances are attributed to multiple factors such as surface impurities on the CAM surface, severe reactions between the lithium metal oxide and sulfide SEs, space charge layer effects, lattice mismatches, and poor wetting of SEs. It is known that the formation of surface impurities, such as LiOH and Li2CO3 on CAM surface in ambient atmosphere conditions, causes the degradation of the electrochemical performances of conventional LIBs. When it comes to ASSBs, the S/O exchange at the CAM/SE interface and the poor ion-conducting properties of the surface impurities are of major concern. The computational modeling by Zhang et al1 reported that the Li+ conductivity in crystalline Li2CO3 is ˜10−10 S cm−1 at room temperature and may lead to a high interfacial resistance. Various protective coatings have been developed to lower the interfacial resistance. LiNbO3 is one of the most studied coating materials for sulfide ASSBs because of its high Li+ conductivity of ˜10−6 S cm−1. US20110045348A1 discloses that a LiNbO3 layer coating on CAM could reduce the interfacial resistance. However, such coating materials may not fully address the challenges. Zhang et al. 2 reported that the transition metal may diffuse from the CAM to the thin film coating. First-principles computation also indicates that the high binding energy of a PO4 group creates a driving force for S/O exchange between the oxygen atoms in the coating of lithium transition metal oxide such as LiNbO3 and LiTaO3 and the S atoms in the sulfide SEs. In addition, the relatively low oxidation limit of these ternary-metal-oxide coatings raises concern for their stability at high voltages. Thus, there remains a need for additional coating materials and all solid-state batteries comprising the same. SUMMARY Disclosed herein is cathode active material (CAM) at least partially coated with a lithium carbonate doped with lithium borate with a formula of Li2+XC1−xBxO3 wherein 0<x<0.5 and a preparation method therefor. Also disclosed is a cathode layer comprising the coated CAM and an all-solid-state battery comprising the cathode layer. The CAM disclosed herein with the recited lithium carbonate doped with lithium borate improves the discharge specific capacity and/or the cycle-life stability when incorporated into an all-solid-state battery. In another aspect, also disclosed herein is a CAM with its surface doped with lithium borate. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows a representative structure of a cathode layer comprising CAM particle (1), a coating around the CAM particle comprised of a thin (1-10 nm) LCBO (Li2+xC1−xBxO3; 0.00<x<0.5) layer (2), an electronically conductive carbon fiber (3), and a sulfide SE (4). FIG. 2 shows a typical structure of an all-solid-state battery (ASSB) comprising a cathode layer (5), a solid electrolyte (6), an anode layer (7), a first current collector (8-1) in contact with the anode layer, and a second current collector (8-2) in contact with the cathode layer. FIG. 3 shows a plot of specific capacity vs. cycle of half-cells comprising a Li metal anode, LPSCl (Li6PS5Cl) SE, and cathode layer comprising particles of NCA88 (LiNi0.88Co0.09Al0.03O2) as CAM, and vapor grown carbon fiber (VGCF). Cycle 1 & 2 are cycled at 0.1 C charge/discharge; cycle 3 & 4 are cycled at 0.33 C charge/discharge, cycle 5 is cycled at 1.0 C charge/discharge, and cycle 6-25 are cycled at 0.5 C charge/discharge. The cycle plots compare NCA88 CAM coated with roughly 5 nm of Li2+xC1−xBxO3 with x=0, 0.05, 0.1, 0.15, 0.25, 0.3, 0.5, and 1. F