Rechargeable lithium sulfur and/or selenium battery

1. An electrochemical device comprising:

a cathode comprising:

a first cathode component comprising lithium and Se x S y , wherein x+y=1, 0≤x≤1, and 0≤y≤1; and

a second cathode component comprising sodium sulfide, sodium selenide, or a mixture thereof;

an anode;

a porous separator; and

a non-aqueous electrolyte comprising one or more lithium salts, and one or more aprotic solvents;

wherein:

the electrochemical device is a lithium sulfur and/or lithium selenide battery.

2. The electrochemical device of claim 1 , wherein the anode comprises lithium.

3. The electrochemical device of claim 1 , wherein the anode is lithium free.

4. The electrochemical device of claim 1 which is an as-prepared device.

5. The electrochemical device of claim 1 further comprising an initial discharge product comprising a polyselenide and/or polysulfide anion compensated by an alkali metal and/or alkaline earth metal cation.

6. The electrochemical device of claim 1 , wherein the lithium salt comprises a lithium alkyl fluorophosphate; a lithium alkyl fluoroborate; lithium 4,5-dicyano-2-(trifluoromethyl)imidazole; lithium 4,5-dicyano-2-methylimidazole; trilithium 2,2′, 2″-tris(trifluoromethyl)benzotris(imidazolate); LiN(CN) 2 ; Li[SO 3 CF 3 ]; Li[CF 3 CO 2 ]; Li[C 2 F 5 CO 2 ]; Li[CH 3 SO 3 ]; Li[N(SO 2 CF 3 ) 2 ]; Li[N(SO 2 F) 2 ]; Li[C(CF 3 SO 2 ) 3 ]; Li[N(SO 2 C 2 F 5 ) 2 ]; LiClO 4 ; LiBF 4 ; LiAlCl 4 ; LiPF 6 ; Li 2 SO 4 ; LiOH; Li[BF 2 (C 2 O 4 )]; Li[B(C 2 O 4 ) 2 ]; Li[PF 2 (C 2 O 4 ) 2 ]; Li[PF 4 (C 2 O 4 )]; LiAsF 6 ; LiSbF 6 ; LiNO 3 ; Li 2 (B 12 X 12 -pHp); Li 2 (B 10 X 10 -pHp); or a mixture of any two or more thereof, wherein X is independently at each occurrence F, Cl, Br, or I, p is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, and p′ is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

7. The electrochemical device of claim 1 , wherein the lithium salt comprises Li[N(SO 2 CF 3 ) 2 ], LiNO 3 , or a mixture thereof.

8. The electrochemical device of claim 1 , wherein a ratio of the first cathode component to the second cathode component is from 80 to 10.

9. The electrochemical device of claim 1 , wherein a ratio of lithium to sodium is from 80 to 10.

10. The electrochemical device of claim 1 , wherein the aprotic solvent comprises an ether.

11. The electrochemical device of claim 10 , wherein the ether is dimethoxyethane (DME), 1,3 dioxolane (DOL), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether (TEGDME), or a mixture of any two or more thereof.

12. The electrochemical device of claim 1 , wherein the cathode, prior to a first discharge charge cycle, is free of polysulfide anion, polyselenide anion, elemental sulfur, and elemental selenium.

13. The electrochemical device of claim 1 which is configured to, after a first charge cycle, comprise elemental sulfur.

14. The electrochemical device of claim 1 , wherein the anode comprises lithium, lithiated carbon, lithiated tin, lithiated silicon, sodium, sodiated carbon, sodiated tin, sodiated silicon, potassium, potassiated carbon, potassiated tin, potassiated silicon, magnesium, magnesiated carbon, magnesiated tin, magnesiated silicon, zinc, zincated carbon, zincated tin, zincated silicon, or a mixture of any two or more thereof.

15. The electrochemical device of claim 1 , wherein the anode further comprises a current collector, a conductive carbon material, a binder, or any combination thereof.

16. The electrochemical device of claim 1 , wherein the porous separator comprises a glass fiber material, a carbon fiber material, polyethylene, solid state membranes, or a combination of any two or more thereof.

17. The electrochemical device of claim 1 , wherein the cathode further comprises:

a current collector comprising copper, stainless steel, or titanium; and

a conductive carbon material comprising synthetic graphite, natural graphite, expanded graphite, graphene, reduced graphene oxide, a metal-organic framework, amorphous carbon, hard carbon, soft carbon, carbon black, acetylene black, carbon spheres, mesocarbon microbeads (MCMB), mesoporous carbon, porous carbon matrix, carbon nanofiber, carbon aerogel, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanotube arrays, or a mixture of any two or more thereof.

18. A process of charging the electrochemical device of claim 1 , the process comprising: applying a first charging current to the electrochemical device in an as-assembled, uncharged state to form polysulfide and/or polyselenide anions within the electrolyte.

19. The process of claim 18 , wherein upon further application of the first charging current, elemental sulfur is formed.