High capacity and stable cathode materials

Patent metadata

Field	Value
Publication number	US-2017338471-A1
Application number	US-201715597025-A
Country	US
Kind code	A1
Filing date	May 16, 2017
Priority date	May 17, 2016
Publication date	Nov 23, 2017
Grant date	—

Abstract

High energy density cathode materials, such as LiNi x Mn y Co z O2 (NMC) cathode materials, with improved discharge capacity (hence energy density) and enhanced cycle life are described, A solid electrolyte, such as lithium phosphate infused inside of secondary particles of the cathode material demonstrates significantly enhanced structural integrity without significant or without any observable particle cracking occurring during charge/discharge processes, showing high capacity retention of more than 90% after 200 cycles at room temperature. In certain embodiments the disclosed cathode materials (and cathodes made therefrom) are formed using nickel-rich NMC and/or are used in a battery system with a non-aqueous dual-Li salt electrolytes.

First claim

We claim:

1 . A cathode material comprising:
LiNi X Mn Y Co Z O 2 (NMC) primary and secondary particles, wherein X+Y+Z=1; and the secondary particles having lithium phosphate diffused within the secondary particles.

2 . The cathode of claim 1 wherein the NMC is nickel-rich NMC and 0.95≧X≧0.5, Y is from 0.025 to 0.3 and Z is from 0.025 to 0.2.

3 . The cathode material of claim 1 wherein the secondary particles further include a coating of lithium phosphate on an outer surface.

4 . The cathode material of claim 1 wherein the lithium phosphate is diffused at least into the mantle of the secondary particles.

5 . The cathode material of claim 1 wherein the lithium phosphate material is diffused into inner cores of the secondary particles.

6 . The cathode material of claim 3 wherein the lithium phosphate coating has been annealed prior to cycling the cathode in a battery system.

7 . The cathode material of claim 3 wherein the secondary particles do not include carbon and/or fluoride in the mantle after the cathode material is cycled at least 5 times in a lithium-ion or a lithium metal battery system.

8 . The cathode of claim 1 wherein X is from 0.6 to 0.9, Y is from 0.1 to 0.2 and Z is from 0.07 to 0.15.

9 . The cathode of claim 1 wherein X is from 0.65 to 0.85, Y is from 0.1 to 0.15 and Z is from 0.1 to 0.15.

10 . The cathode material of claim 1 , wherein the NMC comprises LiNi 0.33 Mn 0.33 Co 0.33 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.5 Mn 0.25 Co 0.25 O 2 , LiNi 0.52 Mn 0.32 Co 0.16 O 2 , LiNi 0.55 Mn 0.30 Co 0.15 O 2 , LiNi 0.58 Mn 0.14 Co 0.28 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 , LiNi 0.64 Mn 0.18 Co 0.18 O 2 , LiNi 0.65 Mn 0.27 Co 0.08 O 2 , LiNi 0.7 Mn 0.2 Co 0.1 O 2 , LiNi 0.7 Mn 0.15 Co 0.15 O 2 , LiNi 0.72 Mn 0.10 Co 0.18 O 2 , LiNi 0.76 Mn 0.14 Co 0.10 O 2 , LiNi 0.8 Mn 0.1 Co 0.1 O 2 , LiNi 0.85 Mn 0.04 Co 0.10 O 2 , LiNi 0.9 Mn 0.05 Co 0.05 O 2 , LiNi 0.95 Mn 0.025 Co 0.025 O 2 , or any combination thereof.

11 . The cathode material of claim 1 , wherein a cathode formed of the cathode material provides a discharge capacity greater than 200 mAh g −1 and retains at least 90% of its capacity after at least 150 cycles in a lithium-ion battery system.

12 . A cathode comprising the cathode material of claim 1 wherein the secondary particles have a lithium phosphate concentration gradient wherein the lithium phosphate concentration in the secondary particles is greatest at outer regions of the secondary particles and lowest at inner regions of the secondary particles.

13 . A cathode comprising:
a cathode material comprising an NMC having primary and secondary particles, wherein the secondary particles are formed of a plurality of primary particles and the secondary particles have lithium phosphate substantially uniformly distributed among grain boundaries of the primary particles within the secondary particles.

14 . The cathode of claim 13 wherein the NMC is nickel-rich NMC and the secondary particles of the NMC do not significantly change morphology after at least 150 cycles in a lithium-ion or a lithium-metal battery system.

15 . A lithium battery comprising:
NMC having primary and secondary particles, the secondary particles formed of multiple primary particles; spaces between the primary particles within the secondary particles; and lithium phosphate diffused into the spaces between the primary particles within the secondary particles; and an electrolyte comprising a mixture of two lithium salts, an additive, and a solvent mixture that forms solid electrolyte interphase layers.

16 . The lithium battery of claim 15 wherein the two lithium salts comprise lithium imide and lithium orthoborate in an organic solvent mixture.

17 . The lithium battery of claim 15 wherein the two lithium salts comprise lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethyanesulfonyl)imide (LiBETI) and any mixture thereof; lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiDFOB) and any mixture thereof.

18 . The lithium battery of claim 15 wherein the additive comprises LiFF 6 , NaPF 6 , KPF 6 , CsPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 , LiAlF 4 , vinylene carbonate (VC), fluoroethylene carbonate (FEC), vinyl ethylene carbonate (VEC), methylene ethylene carbonate (MEC), tetrafluoroethylene carbonate (TFEC), trifluoropropylene carbonate (TFPC), 1,3-propylsultone, 1,4-butylsultone, or any mixture thereof.

19 . The lithium battery of claim 15 wherein the solvent comprises carbonate,ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), dipropyl carbonate (DPC), di(2,2,2-trifluoroethyl) carbonate (DTFEC), or any mixture thereof, a sulfone, dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), tetramethylene sulfone; carboxylates, methyl butyrate (MB), ethyl propionate (EP); a phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate; phosphites such as triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, an ether, nonafluorobutyl methyl ether, nonafluorobutyl ethyl ether, a nitrile, butyronitrile, succinonitrile, or any mixture thereof.

20 . A method for making a lithium battery cathode, comprising:
providing an NMC precursor; combining the NMC precursor with a lithium source to form a mixture; sintering the NMC precursor and lithium source mixture to form a nickel-rich NMC particles; coating the NMC particles with lithium phosphate; heating the lithium phosphate coated NMC particles in an environment at a temperature between from 600° C. to 800° C. to infuse lithium phosphate from the coating into the NMC cathode material; and forming a cathode from the lithium phosphate infused NMC cathode material.

21 . The method of claim 20 wherein the lithium source is LiOH, Li2CO 3 , LiNO 3 , Li 2 CO 3 , lithium acetate, or any mixture thereof.

22 . The method of claim 20 wherein the NMC precursor is NMC(OH) 2 .

23 . The method of claim 22 wherein the precursor NMC(OH) 2 is combined with a the phosphate source to form a mixture which is then sintered at high temperature to form lithium phosphate coated NMC(OH) 2 .

24 . The method of claim 17 wherein the lithium phosphate coated nickel-rich NMC particles are annealed to form the lithium phosphate infused NMC cathode material.

25 . The method of claim 20 wherein the NMC precursor is NMC(OH) 2 .

Assignees

• Battelle Memorial Institute

Inventors

• Zheng Jianming
• Zhang Jiguang
• Yan Pengfei
• Wang Chongmin
• Zhao Wengao
• Chen Shuru
• Xu Wu

Classifications

• H01M10/0569

  characterised by the solvents · CPC title

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/525

  of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy · CPC title