ϵ-VOPO4 cathode for lithium ion batteries

Patent metadata

Field	Value
Publication number	US-11715829-B2
Application number	US-202217670470-A
Country	US
Kind code	B2
Filing date	Feb 13, 2022
Priority date	Mar 5, 2018
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

The epsilon polymorph of vanadyl phosphate, ε-VOPO 4 , made from the solvothermally synthesized H 2 VOPO 4 , is a high density cathode material for lithium-ion batteries optimized to reversibly intercalate two Li-ions to reach the full theoretical capacity at least 50 cycles with a coulombic efficiency of 98%. This material adopts a stable 3D tunnel structure and can extract two Li-ions per vanadium ion, giving a theoretical capacity of 305 mAh/g, with an upper charge/discharge plateau at around 4.0 V, and one lower at around 2.5 V.

First claim

The invention claimed is:

1. A method of making a lithium ion battery cathode, comprising:
forming ε-VOPO 4 particles having a diameter of 100-200 nm;
coating the ε-VOPO 4 particles with conductive carbon, to form coated ε-VOPO 4 particles;
adding a binder to the coated ε-VOPO 4 , particles to form a mixture;
depositing the mixture on a current collector,
wherein the deposited mixture has a capacity of at least 275 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20.

2. The method according to claim 1 , wherein the ε-VOPO 4 particles are solvothermally generated.

3. The method according to claim 1 , wherein the ε-VOPO 4 particles are hydrothermally generated.

4. The method according to claim 1 , wherein said coating comprises mixing the ε-VOPO 4 particles with graphene nanoplatelets.

5. The method according to claim 4 , wherein the graphene nanoplatelets have a surface area of at least 100 m 2 /g.

6. The method according to claim 1 , wherein the binder comprises polyvinylidene fluoride.

7. The method according to claim 1 , wherein the ε-VOPO 4 particles are coated with carbon nanotubes.

8. The method according to claim 1 , wherein the coated ε-VOPO 4 particles have a coating thickness of 10 nm.

9. The method according to claim 1 , wherein the ε-VOPO 4 particles of the lithium ion battery cathode comprises a vanadium which is adapted to undergo a change in oxidation state of two between a charged state filled with intercalated lithium ions and a discharged state depleted of intercalated lithium ions.

10. The method according to claim 9 , wherein the lithium ion battery cathode has a current-voltage profile which displays voltage plateaus on discharge at a discharge rate of C/20, at about 2.1 V, 2.25 V, 2.5 V, and 3.9 V.

11. The method according to claim 10 , wherein the ε-VOPO 4 particles have a capacity of at least 305 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20.

12. The method according to claim 10 , wherein the lithium ion battery cathode has a discharge capacity of at least 90% of a theoretical value for the discharge capacity of the ε-VOPO 4 particles.

13. The method according to claim 9 , wherein the ε-VOPO 4 particles have a capacity of at least 290 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20.

14. The method according to claim 1 , wherein the ε-VOPO 4 particles have an energy capacity of at least 850 mWh/g.

15. The method according to claim 1 , wherein the conductive carbon comprises graphene particles, and the mixture comprises between 5% and 15% by weight of the graphene particles.

16. The method according to claim 1 , wherein the mixture comprises at least 75% by weight ε-VOPO 4 particles, at least 5% by weight graphene nanoplatelets, and at least 5% by weight of a binder.

17. The method according to claim 1 , wherein the lithium ion battery cathode has at least two states, comprising:
a first state in which at least 80 mol % of vanadium of the ε-VOPO 4 particles is oxidized in a first oxidation state and associated with two lithium ions per vanadium, and
a second state in which at least 80 mol % of the ε-VOPO 4 particles is oxidized in a second oxidation state which differs by two from the first oxidation state.

18. The method according to claim 1 , further comprising forming a lithium ion battery comprising:
the lithium ion battery cathode;
a lithium or lithium ion anode;
an electrolyte adapted to operate at a battery potential of at least 4.5 V; and
a supporting lithium salt.

19. A method of making a lithium ion battery cathode, comprising:
combining ε-VOPO 4 , particles having a diameter of 100-200 nm coated with electrically conductive carbon particles, and a binder to form a mixture; and
coating a current collector with a slurry of the mixture,
wherein the ε-VOPO 4 has a dual lithium ion exchange characteristic, having a capacity of about 125 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20 while maintaining a voltage exceeding 3.7 V and a capacity of at least 275 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20 while maintaining a voltage exceeding 1.6 V.

20. A lithium ion battery cathode, comprising a mixture of ε-VOPO 4 particles having a size of 100-200 nm, coated with electrically conductive graphene, and a binder, on a current collector, having a capacity of at least 275 mAh per gram of Li 2 VOPO 4 at a discharge rate of C/20.

Assignees

• Univ New York State Res Found
• The Research Foundation For The State Univ

Inventors

• Siu Carrie
• Whittingham M Stanley

Classifications

• H01M4/5825 Primary

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

• C01B25/372 Primary

  of titanium, vanadium, zirconium, niobium, hafnium or tantalum · CPC title

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M4/1397

  of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• H01M4/623

  fluorinated polymers · CPC title