SILICON-BASED ENERGY STORAGE DEVICES WITH PHOSPHAZENE CONTAINING ELECTROLYTE ADDITIVES

1 . A method of forming an energy storage device, the method comprising: forming an energy storage device comprising:

a positive electrode;

a negative electrode comprising an active material comprising silicon;

a separator between the positive electrode and the negative electrode; and

an electrolyte system;

wherein one or more of said anode, said cathode and said electrolyte system comprises at least one additive, wherein said additive comprises a phosphazene based compound at a concentration of about 0.1%-10%;

wherein one or both of said cathode and said anode is formed using, at least, the following steps:

said electrode material is mixed to create a slurry;

said additive is added to said slurry;

said slurry is coated on metal foil; and

the coated metal foil is dried.

2 . The method of claim 1 , wherein the phosphazene based compound is selected from formulae (A), (B), (C), or combinations thereof:

wherein:

each R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 are independently selected from the group consisting of —R 0 , —OR, —NHR′, —NR′R′, —SR″, —NCS and —N 3 , provided that not all of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 in Formula (A) are —R 0 , and not all of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 in Formula (B) are —R 0 ;

each R 0 is selected from the group consisting of C1-C6 alkyl and C2-C6 alkenyl;

each R is selected from the group consisting of a C1-C10 alkyl substituted by —F, C1-C3 alkyl, —N 3 or methacrylate, a C1-C10 heteroalkyl with 1 or more O heteroatom substituted by —F, a C1-C3 alkyl, —N 3 or methacrylate, a C2-C10 alkenyl, a C2-C10 heteroalkenyl with 1 or more O heteroatom, a C2-C10 alkynyl, a C2-C10 heteroalkynyl with 1 or more O heteroatom, and a phenyl substituted by —C≡CH; or R is taken together with an adjacent R form a ring structure;

each R′ is independently selected from the group consisting of a C1-C10 alkyl optionally substitutes by —F or —COOR 9 , a C1-C10 heteroalkyl with 1 or more O heteroatom optionally substituted by —F or —COOR 9 , a C2-C10 alkenyl, a C2-C10 heteroalkenyl with 1 or more O heteroatom, a C2-C10 alkynyl, a C2-C10 heteroalkynyl with 1 or more O heteroatom, and a phenyl substituted by —C≡CH; or R′ is taken together with an adjacent R′ form a ring structure optionally substituted by C1-C3 alkyl;

each R″ is independently selected from the group consisting of a C1-C10 alkyl optionally substitutes by —F or —COOR 9 , a C1-C10 heteroalkyl with 1 or more O heteroatom optionally substituted by —F or —COOR 9 , a C2-C10 alkenyl, C2-C10 heteroalkenyl with 1 or more O heteroatom, a C2-C10 alkynyl substituted by —F, and a C2-C10 heteroalkynyl with 1 or more O heteroatom substituted by —F; or R″ is taken together with an adjacent R′ form a ring structure substituted by one or more —F; and

each R 9 is independently a C1-C3 alkyl.

3 . The method of claim 1 , wherein the phosphazene based compound is selected from the group consisting of Hexakis(1H,1H-trifluoroethoxy)phosphazene (H3FPZ); Hexakis(1H,1H-pentafluoropropoxy)phosphazene (H5FPZ); Hexakis(1H,1H-perfluorobutoxy)phosphazene; Hexakis(1H,1H-nonafluoropentoxy)phosphazene; Hexakis(1H,1H-perfluorohexyloxy)phosphazene; Hexakis(1H,1H-perfluoroheptoxy)phosphazene; Hexakis(1H,1H-perfluorooctyloxy)phosphazene; Hexakis(1H,1H-perfluorononyloxy)phosphazene; Hexakis(hexafluoroisopropoxy)phosphazene; Hexakis(2-fluoropropoxy)phosphazene; Hexakis(1H,1H,2H-difluoroethoxy)phosphazene; Hexakis(2,2-difluoropropoxy)phosphazene; Hexakis(2-fluoropropoxy)phosphazene; Hexakis(3,3,3-trifluoro-2,2-dimethylpropoxy)phosphazene; Hexakis(1H,1H,3H-tetrafluoropropoxy)phosphazene; Hexakis(2,2,3,4,4,4-hexafluorobutoxy)phosphazene; Hexakis(1H,1H,4H-perfluorobutoxy)phosphazene; Hexakis(1H,1H,5H-octafluoropentoxy)phosphazene; Hexakis(1H,1H,7H-perfluoroheptoxy)phosphazene; Hexakis(3,3,3-trifluoropropoxy)phosphazene; Hexakis(1H,1H,2H,2H-heptafluoropentoxy)phosphazene; Hexakis(3,4,4,4-tetrafluoro-3 (trifluoromethyl)butoxy)phosphazene; Hexakis(1H,1H,2H,2H-perfluorohexyloxy)phosphazene; Hexakis(3,3-bis(trifluoromethyl)-4,4,4-trifluorobutoxy)phosphazene; Hexakis(3,3,3-trifluoro-2,2-dimethylpropoxy)phosphazene; Hexakis(2-(2,2,2-Trifluoroethoxy)ethoxy)phosphazene or Hexakis[1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoxy)]phosphazene; Hexakis(4,4,4-trifluorobutoxy)phosphazene; Hexakis(4,4,5,5,5-pentafluoropentoxy)phosphazene; Hexakis(4,4,5,5,6,6,6-heptafluorohexoxy)phosphazene; Hexakis(3-fluoropropoxy)phosphazene; Hexaallyloxyphosphazene (HALPZ); 2-methyl-2-prop-2-enyl-4,4,6,6-tetrakis(2,2,2-trifluoroethoxy)-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-triene; hexa(methacryloylethylenedioxy)cyclotriphosphazene; Hexakis-(diethylamino)-cyclotriphosphazatrien; Hexakis-(diethylamino)-cyclotriphosphazatrien; Hexakis(allylamino)cyclotriphosphazene; Hexa-pyrrolidin-1-yl-2λ5,4λ5,6λ5-cyclotriphosphazene; Apholate; Methyl apholate; 2,4,4,6,6-pentakis(aziridin-1-yl)-N,N-dimethyl-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-trien-2-amine; 2,4,4,6,6-pentakis(aziridin-1-yl)-N-methyl-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-trien-2-amine; 2,2,4,4-tetrakis(aziridin-1-yl)-1,3,5,7,11-pentaza-2λ5,4λ5,6λ5-triphosphaspiro[5.5]undeca-1(6),2,4-triene; 2,2,4,4,6-pentakis(aziridin-1-yl)-6-piperidin-1-yl-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-triene; Fotretamine; 4-[(2R)-2,4,4,6-tetrakis(aziridin-1-yl)-6-morpholin-4-yl-1,3,5-triaza-2,1,3,5,2,4,6-Triazatriphosphorine; 2,2,4,4-tetra(aziridin-1-yl)-6,6-di(piperidin-1-yl)-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinine; (6S)-2,2,4,6-tetrakis(aziridin-1-yl)-4,6-di(piperidin-1-yl)-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-triene; 2,2,4,4-tetrakis(aziridin-1-yl)-6,6-dipyrrolidin-1-yl-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-triene; 4,4′-(4,4,6,6-tetra(aziridin-1-yl)-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinine-2,2-diyl)dimorpholine; 2,2,4,4,6,6-hexahydro-4,6-bis(dimethylamino)-2,2,4,6-tetrakis(1-aziridinyl)-1,3,5,2,4,6-Triazatriphosphorine; 4,4,6,6-tetra(aziridin-1-yl)-N,N,N′,N′-tetramethyl-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinine-2,2-diamine; 2,4,4,6,6-penta(aziridin-1-yl)-N,N-dimethyl-1,3,5,2λ 5 ,4λ 5 ,6λ 5 -triazatriphosphinin-2-amine; Ethyl 2-[[4,4,6,6-tetrakis(aziridin-1-yl)-2-[(2-ethoxy-2-oxoethyl)amino]-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-trien-2-yl]amino]acetate; (4R,6S)-4,6-bis(aziridin-1-yl)-2-N,2-N′,4-N,6-N-tetramethyl-1,3,5-triaza-2λ5,4λ5,6λ5-triphosphacyclohexa-1,3,5-triene-2,2,4,6-tetramine; 2,2,4,4,6,6-hexakis-methylsulfanyl-2λ5, 4λ5, 6λ5-cyclotriphosphazene; hexaazido cyclotriphosphazene; 2,2,4,4,6,6,8,8-Octakis(dimethylamino)-1,3,5,7,2,4,6,8-tetrazatetraphosphocine; 2,2,4,4,6,6,8,8-octakis(aziridin-1-yl)-1,3,5,7-tetraza-2λ5,4λ5,6λ5,8λ5-tetraphosphacycloocta-1,3,5,7-tetraene; 2,2,4,4,6,6,8,8-octapyrrolidin-1-yl-1,3,5,7-tetraza-2; 2,2,4,4,6,6,8,8-Octa-1-pyrrolidinyl-1,3,5,7,2,4,6,8-tetraphosphazene; 2,2,4,4,6,6,8,8-octakis(piperidin-1-yl)-1,3,5,7-tetraza-2,4,6,8-tetraphosphacycloocta-1,3,5,7-tetraene; Octamorpholinocyclotetraphosphazene; (6R,8S)-6,8-bis(aziridin-1-yl)-2-N,2-N′,4-N,4-N′,6-N,8-N-hexamethyl-1,3,5,7-tetraza-2λ5,4λ5,6λ5,8λ5-tetraphosphacycloocta-1,3,5,7-tetraene-2,2,4,4,6,8-hexamine; 4,8-Bis(1-aziridinyl)-N2,N2,N4,N6,N6,N8-hexamethyl-1,3,5,7,2λ5,4λ5,6λ5,8λ5-tetrazatetraphosphocine-2,2,4,6,6,8-hexamine; (4S,8R)-4,8-bis(aziridin-1-yl)-2-N,2-N,2-N′,2-N′,4-N,4-N,6-N,6-N,6-N′,6-N′,8-N,8-N-dodecamethyl-1,3,5,7-tetraza-2λ5,4λ5,6λ5,8λ5-tetraphosphacycloocta-1,3,5,7-tetraene-2,2,4,6,6,8-hexamine; and 2,2,4,4,6,6,8,8-octakis(2,2,2-trifluoroethoxy)-1,3,5,7-tetraza-2λ5,4λ5,6λ5,8λ5-tetraphosphacycloocta-1,3,5,7-tetraene, or a combination thereof.

4 . The method of claim 3 , wherein the phosphazene based compound is selected from the group consisting of H3FPZ, H5FPZ and HALPZ, or a combination thereof.

5 . The method of claim 1 , wherein said additive comprising a phosphazene based compound is present in the electrolyte system.

6 . The method of claim 5 , wherein said electrolyte system further comprises:

a linear carbonate at a concentration of about 30%-60%;

a fluorine containing cyclic carbonate at a concentration of about 5%-40%; and

a Li-containing salt at a concentration of 1.0-1.5 M.

7 . The method of claim 6 , wherein the linear carbonate is selected from the group consisting of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC).

8 . The method of claim 6 , wherein the fluorine containing cyclic carbonate is selected from the group consisting of fluoroethylene carbonate (FEC), di-fluoroethylene carbonate (DiFEC), and Trifluoropropylene carbonate (TFPC).

9 . The method of claim 8 , wherein the fluorine containing cyclic carbonate is fluoroethylene carbonate (FEC).

10 . The method of claim 6 , wherein the electrolyte system is substantially free of non-fluorine containing cyclic carbonate.

11 . The method of claim 6 , wherein the Li-containing salt is a fluorinated Li salt.

12 . The method of claim 1 , wherein the negative electrode active material consists essentially of silicon.

13 . The method of claim 1 , wherein the negative electrode comprises greater than 50% and less than about 99% by weight of silicon as silicon particles.

14 . The method of claim 13 , wherein the negative electrode comprises greater than 50% and less than about 90% by weight of the silicon particles.