Pnictide containing catalysts for electrochemical conversion reactions and methods of use

Patent metadata

Field	Value
Publication number	US-10388947-B2
Application number	US-201514615782-A
Country	US
Kind code	B2
Filing date	Feb 6, 2015
Priority date	Feb 6, 2015
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

Graphitic carbon nitride materials are shown to be useful in Lithium-Sulfur electrochemical cells. Batteries that include this material exhibit increased electrode kinetics of the lithium-sulfur electrochemical couple, phenomena that improve the specific capacity, usable lifetime and other desirable characteristics of these batteries. Lithium-sulfur batteries that incorporate these materials can be used to overcome a number of limitations in this technology.

First claim

The invention claimed is:

1. A lithium-sulfur electrochemical cell comprising:
an anode;
a sulfur-carbon cathode;
a separator disposed between the anode and the cathode;
an electrolyte solution;
sulfur; and
a graphitic carbon nitride having the formula:

wherein:
R1, R2 and R3 are each independently:
(a) —NH 2 ;
(b) —NH—R4; or
(c) —N—(R4) 2 ; wherein R4 is:

and
the graphitic carbon nitride compound has an electrical conductivity<1×10 −7 cm/s; and
the cathode is formed from a composite material comprising graphitic carbon nitride, sulfur, conductive carbon nanoparticles and a polymeric material.

2. The lithium-sulfur electrochemical cell of claim 1 , further comprising a membrane disposed between the separator and the cathode, wherein the membrane comprises graphitic carbon nitride.

3. The lithium-sulfur electrochemical cell of claim 1 , wherein the graphitic carbon nitride is disposed in a composite material comprising at least one of: reduced graphene oxide, graphene oxide, and at least one conducting polymer selected from the group consisting of polyaniline, polypyrrole, polythiphene and poly(3,4-ethylenedioxythiophene.

4. The lithium-sulfur electrochemical cell of claim 1 , wherein the graphitic carbon nitride is doped with at least one of: sulfur, carbon, phosphorus, or boron.

5. The lithium-sulfur electrochemical cell of claim 1 , wherein the lithium-sulfur electrochemical cell is a full electrochemical cell.

6. The lithium-sulfur electrochemical cell of claim 1 , wherein the electrolyte solution comprises at least one of: glyme, an ether, a phosphate, a fluoride, a tetrafluoroborate, a bis(trifluoromethanesulfonyl)imide, a bis(fluorosulfonyl)imide, a nitrate, a cyanate, a pyridinic, a thiocyanzte alkali, and an alkaline earth metal salt.

7. The lithium-sulfur electrochemical cell of claim 1 , wherein:
the lithium-sulfur electrochemical cell generates lithium polysulfides; and
the graphitic carbon nitride is disposed in the lithium-sulfur electrochemical cell so that the lithium polysulfides contact and bind the graphitic carbon nitride.

8. The lithium-sulfur electrochemical cell of claim 1 , wherein the graphitic carbon nitride is disposed at a location in the lithium-sulfur battery so as to:
(a) act as a sorbent to attract soluble polysulfides and limit their bulk diffusion into the electrolyte solution;
(b) catalyze oxidation-reduction reactions of a lithium sulfur catholyte;
(c) catalyze oxidation-reduction of a crystalline lithium sulfide;
(d) catalyze oxidation-reduction of a crystalline sulfur; or
(e) reduce electrode charge transfer resistance.

9. A lithium-sulfur battery comprising:
an anode;
a sulfur-carbon cathode;
a separator disposed between the anode and the cathode;
an electrolyte solution;
sulfur; and
a graphitic carbon nitride having the formula:

wherein:
R1, R2 and R3 are each independently:
(a) —NH 2 ,
(b) —NH—R4; or
(c) —N—(R4) 2 ; wherein R4 is:

and
the graphitic carbon nitride is disposed at a location within the lithium-sulfur battery that allows the graphitic carbon nitride to function as a catalyst of redox electrochemical reactions within the lithium-sulfur battery.

10. The lithium-sulfur battery of claim 9 , wherein:
the electrochemical cell generates lithium polysulfides; and
the graphitic carbon nitride in the electrochemical cell catalyzes the oxidization or reduction of the lithium polysulfides.

11. The lithium-sulfur battery of claim 9 , wherein the graphitic carbon nitride functions to decrease charge transfer resistance within the electrochemical cell.

12. The lithium-sulfur battery of claim 9 , wherein:
the lithium-sulfur electrochemical cell further comprises a membrane disposed between the separator and the cathode; and
the membrane comprises graphitic carbon nitride.

13. The lithium-sulfur battery of claim 9 , wherein the cathode is formed from a composite material comprising graphitic carbon nitride.

14. The lithium-sulfur battery of claim 10 , wherein the cathode is formed from a composite material comprising sulfur.

15. A lithium-sulfur electrochemical cell comprising:
an anode;
a sulfur-carbon cathode;
a separator disposed between the anode and the cathode;
a catholyte solution comprising solubilized lithium polysulfides; and
a graphitic carbon nitride having the formula:

wherein:
R1, R2 and R3 are each independently:
(a) —NH 2
(b) —NH—R4; or
(c) —N—(R4) 2 ; wherein R4 is:

and
the graphitic carbon nitride is in contact with the catholyte solution comprising solubilized lithium polysulfides.

16. The lithium-sulfur electrochemical cell of claim 15 , wherein the graphitic carbon nitride functions to lower cathodic impedance within the electrochemical cell.

17. The lithium-sulfur electrochemical cell of claim 16 , wherein the graphitic carbon nitride functions as a catalyst of redox electrochemical reactions within the electrochemical cell.

18. The lithium-sulfur electrochemical cell of claim 17 , wherein the cathode comprises the graphitic carbon nitride is bound with a polymer and disposed within a conductive carbon matrix.

Assignees

• Univ California
• Mitsubishi Chem Corp

Inventors

• Jun Young-Si
• Gerbec Jeffrey A
• Stucky Galen D

Classifications

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• H01M4/136

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

• H01M4/38

  of elements or alloys · CPC title

• H01M4/364 Primary

  as mixtures · CPC title