Additive for lithium ion rechageable battery cells

• US 8,945,774 B2
• Filed: 06/07/2011
• Issued: 02/03/2015
• Est. Priority Date: 06/07/2010
• Status: Active Grant

• Current Assignee: SK On Company Limited (SK Innovation Company Limited)
• Original Assignee: Nexeon Limited
• Inventors: Coowar, Fazlil, Abdelsalam, Mamdouh Elsayed, Lain, Michael Jonathan
• Primary Examiner(s): DIAO, M BAYE
• Application Number:
  US13/265,464
• Publication Number:
  US 20130069601A1
• Time in Patent Office: 1,337 Days
• Field of Search: 429/231.8, 429/232, 429/331, 429/332
• US Class Current: 429/231.8
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/056 characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
• CPC Class Codes: H01M 10/0566 Liquid materials
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 2300/0034 Fluorinated solvents
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/387 Tin or alloys based on tin
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention claims the addition of vinylene carbonate (VC) and optionally also fluoroethylene carbonate to the electrolyte of lithium ion cells having a structural silicon composite anode, i.e. an anode containing fibers or particles of silicon. The additive significantly improves the cycling performance of the cells. A VC content in the range 3.5-8 wt % based on the weight of the electrolyte has been found to be optimum.

Claims

1. A lithium ion rechargeable battery cell comprising:

a porous anode comprising structured electroactive material-containing particles that are structured to provide space between or within the particles for the expansion of the electroactive material during lithiation;

a cathode comprising an active material capable of incorporating lithium and also of liberating lithium electrochemically; and

an electrolyte;

wherein the electrolyte comprises both a cyclic carbonate including a vinyl group and a fluorinated cyclic carbonate, wherein the total amount of the cyclic carbonate including a vinyl group and the fluorinated cyclic carbonate together is in the range 3.5 wt % to 70 wt % based on the total weight of the electrolyte solution.

2. A lithium ion rechargeable battery cell according to claim 1, where the structured electroactive material-containing particles comprise one or more of Si, Sn, Ge, and Ga.

3. A lithium ion rechargeable battery cell as claimed in claim 1 wherein the structured electroactive material-containing particles are fibres selected from the group comprising tin-containing fibres, germanium-containing fibres, gallium containing fibres and silicon-containing fibres with a diameter of 10-500 nm and length of 1-150 μ

m, such fibres optionally being provided in the form of a scaffold or felt comprising such fibres.

4. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are fibres selected from the group comprising tin-containing fibres, gallium containing fibres and silicon-containing fibres with a diameter of 50-250 nm and length of 1-80 μ

m, such fibres optionally being provided in the form of a scaffold or felt comprising such fibres.

5. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are tubes selected from the group comprising tin-containing tubes, germanium-containing tubes, gallium containing tubes and silicon-containing tubes with a wall thickness of ≧

10 nm and length of ≧

1 μ

m.

6. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are ribbons selected from the group comprising tin-containing ribbons, gallium containing ribbons and silicon-containing ribbons with a thickness of 50-200 nm, a width of 500 nm to 1 μ

m and a length of ≧

1 μ

m or felts comprising such ribbons.

7. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are flakes selected from the group comprising tin containing flakes, gallium containing flakes and silicon-containing flakes with a thickness of 50-200 nm and the two other dimensions in the range of 1-20 μ

m.

8. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are silicon-containing pillared particles consisting of a silicon-based particle core of diameter 5-25 μ

m with an array of silicon pillars attached thereto, the pillars having diameter of no more than 1000 nm and a length of 1-5 μ

m.

9. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are silicon-containing porous particles, each particle having a network of voids or pores extending therethrough.

10. A lithium ion rechargeable battery cell as claimed in claim 9 wherein at least some of the walls between adjacent pores have a thickness of ≧

10 nm and extend over a length of ≧

100 nm, and wherein the diameter of the porous particle is 1-30 μ

m.

11. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the structured electroactive material-containing particles are carbon coated.

12. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the electroactive material-containing particles comprise silicon with a purity of 90-99.990% by weight.

13. A lithium ion rechargeable battery cell as claimed in claim 1, wherein substantially all the active material in the anode comprises silicon.

14. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises 1-8 wt % of a cyclic carbonate including a vinyl group based on the total weight of the electrolyte.

15. A lithium ion rechargeable battery cell according to claim 14, wherein the electrolyte comprises at least 3 wt % of a fluorinated cyclic carbonate based on the total weight of the electrolyte.

16. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises at least 2%, 3%, 5%, 10% or 15% by weight of a cyclic carbonate including a vinyl group.

17. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises 3.5 to 8% by weight of a cyclic carbonate including a vinyl group.

18. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises at least 10% by weight of a fluorinated cyclic carbonate.

19. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises at least 15% by weight of a fluorinated cyclic carbonate.

20. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises at least 30% by weight of a fluorinated cyclic carbonate.

21. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte comprises no more than 50% by weight of a fluorinated cyclic carbonate.

22. A lithium ion rechargeable battery cell according to claim 1, wherein the cyclic carbonate including a vinyl group is vinylene carbonate.

23. A lithium ion rechargeable battery cell according to claim 1, wherein the fluorinated cyclic carbonate is fluoroethylene carbonate, difluoroethylene carbonate or a mixture thereof.

24. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the electrolyte initially includes 0.05 to 0.25 wt % dissolved CO₂.

25. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte includes a cyclic carbonate including a vinyl group, a fluorinated cyclic carbonate and dissolved CO₂.

26. A lithium ion rechargeable battery cell according to claim 1 wherein the cyclic carbonate including a vinyl group is vinylene carbonate and the fluorinated cyclic carbonate is fluoroethylene carbonate, difluoroethylene carbonate or a mixture thereof.

27. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte solution further comprises a C_1-8 chain carbonate.

28. A lithium ion rechargeable battery cell according to claim 27, wherein the C_1-8 chain carbonate is selected from one or more of dimethylcarbonate, diethyl carbonate, and ethyl methyl carbonate.

29. A lithium ion rechargeable battery cell according to claim 27, wherein the ratio of the cyclic carbonate (including a cyclic carbonate including a vinyl group and/or a fluorinated cyclic carbonate) to the C_1-8 chain carbonate is in the range 30:

70 to 50;

50.

30. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte solution further comprises a cyclic carbonate other than a cyclic carbonate including a vinyl group or a fluorinated cyclic carbonate.

31. A lithium ion rechargeable battery cell according to claim 30, wherein the cyclic carbonate is selected from one or more of the group comprising ethylene carbonate, propylene carbonate, and butylene carbonate.

32. A lithium ion rechargeable battery cell according to claim 1 comprising structured electroactive material-containing particles comprising silicon, a cathode comprising an active material capable of incorporating lithium and also of liberating lithium electrochemically and an electrolyte, wherein (1) the electrolyte comprises 1 to 8 wt % of a cyclic carbonate containing a vinyl group and, at least 3 wt % of a fluorinated cyclic carbonate.

33. A lithium ion rechargeable battery cell according to claim 1, wherein the electrolyte further comprises an electrolyte salt, wherein the electrolyte salt is dissolved in the electrolyte solution to a concentration of between 0.7 to 2M.

34. A lithium ion rechargeable battery cell according to claim 33, wherein the electrolyte comprises one or a mixture of lithium containing electrolyte salts selected from the group comprising LiPF₆, LiBOB, LiClO₄ or a mixture thereof.

35. A lithium ion rechargeable battery cell according to claim 34, wherein the electrolyte comprises LiPF₆ at a concentration of 0.9M and LiBOB at a concentration of 0.1M.

36. A lithium ion rechargeable battery cell according to claim 1, wherein the structured electroactive material-containing particles are selected from one or more of the following:

a) particles having spaced-apart structural elements on their surface, the smallest dimension of the structural elements on the particle surface being at least 10 nm and less than or equal to 10 μ

m and having an aspect ratio of at least 5, wherein the aspect ratio is defined as the ratio of the largest to smallest dimensions of the structural element;

b) particles that have pores or voids dispersed therein, each pore or void being defined by one or more walls having an average wall thickness of ≧

10 nm;

c) particles comprising fragments of particles that have pores or voids dispersed therein, each pore or void being defined by one or more walls having an average thickness of ≧

10 nm;

d) particles having a minimum dimension of at least 10 nm and an aspect ratio of at least 5, wherein the aspect ratio is defined as the ratio of the smallest to largest dimension;

e) particles comprising a columnar bundle of nano-rods having a diameter of 50 to 100 nm and a length of 2 to 5 μ

m, wherein each nano-rod has diameter of at least 10 nm;

f) felt structures formed from particles as defined in (d) above;

g) scaffold structures formed from particles as defined in (d) above;

h) or a mixture thereof.

37. A lithium ion rechargeable battery cell as claimed in claim 1, wherein the anode comprises a porous composite comprising the structured electroactive material-containing particles and at least one other component selected from:

another active material that can reversibly react electrochemically with lithium, a binder, a conductive material, a viscosity adjuster, a filler or a coupling agent.

38. A lithium ion rechargeable battery cell according to claim 1 wherein the structured electroactive material-containing particles have a smallest dimension of at least 10 nm and a largest diameter that is less than 60 μ

m.