Solid composite electrolyte
The invention relates to a solid composite electrolyte comprising: i) at least one solid inorganic particle, ii) at least one ionic liquid electrolyte, and iii) at least one ionically non-conductive polymer, wherein the at least one solid inorganic particle i) is ionic conductive and is blended with the at least one ionic liquid electrolyte ii). The invention also relates to a process for manufacturing the solid composite electrolyte, to a solid state battery comprising the solid composite electrolyte, and to the use of said solid composite electrolyte in a solid state battery for improving ionic conductivity and mechanical properties.
1. A solid composite electrolyte comprising:
i) at least one solid inorganic particle,
ii) at least one ionic liquid electrolyte, and
iii) at least one ionically non-conductive polymer,
wherein the at least one solid inorganic particle i) is ionic conductive and is blended with the at least one ionic liquid electrolyte ii) such that at least part of the at least one ionic liquid electrolyte covers at least part of the surface of the at least one solid inorganic particle, reducing grain-to-grain resistance between the at least one solid inorganic particle;
wherein an amount of the at least one solid inorganic particle i) is from 60.0 to 98.0% by weight (wt %), based on the total weight of the solid composite electrolyte; and
wherein the ionic liquid electrolyte comprises:
a positively charged cation selected from the group consisting of imidazolium, pyridinium, pyrrolidinium and piperidinium ions optionally containing one or more C 1 -C 30 alkyl groups, and
a negatively charged anion selected from the group consisting of halides, fluorinated anions and borates,
wherein C 1 -C 30 alkyl groups include methyl, ethyl, propyl, iso-propyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, 2,2-dimethyl-propyl, hexyl, 2,3-dimethyl-2-butyl, heptyl, 2,2-dimethyl-3-pently, 2-methyl-2-hexyl, octyl, 4-methyl-3-heptyl, nonyl, decyl, undecyl, and dodecyl groups.
2. The solid composite electrolyte according to claim 1 , wherein the at least one solid inorganic particle i) is a garnet-type inorganic particle having a general formula of M 1 a M 2 b M 3 c O d , wherein
M 1 is a first cationic element selected from the group consisting of H, Li, Na, Mg, Al and Ga;
M 2 is a second cationic element selected from the group consisting of La, Ba, Sr, Ca, In, Mg, Y, Sc, Cr, Al, K, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu;
M 3 is a third cationic element selected from the group consisting of Zr, Ta, Nb, Sb, Sn, Hf, Bi, W, Si, Se, Ga, and Ge; and
a, b, c and d are positive numbers including various combinations of integers and decimals.
3. The solid composite electrolyte according to claim 1 , wherein the at least one solid inorganic particle i) is a garnet-type inorganic particle having a general formula of Li x La y Zr z A w O 12 , wherein:
A represents one or several dopants selected from the group consisting of Al, Ga, Nb, Fe, Nd, Pt, Ta, W, Mo, Hf, Si, Ca, Sr, Ba, Ge, and mixtures thereof;
w, x, y, and z are positive numbers, including various combinations of integers, zero and fractions or decimals;
0<y≤3;
0<z≤2;
0≤w≤0.5; and
x is derived from electroneutrality of the garnet structure.
4. The solid composite electrolyte according to claim 3 , wherein A represents one or several dopants selected from the group consisting of Al, W, Ga or combinations thereof.
5. The solid composite electrolyte according to claim 1 , wherein the at least one ionic liquid electrolyte ii) comprises at least one ionic liquid and at least one Li salt.
6. The solid composite electrolyte according to claim 5 , wherein the lithium salt comprises at least one selected from the group consisting of lithium hexafluorophosphate (LiPF 6 ), lithium bis(fluorosulfonyl)imide Li (FSO 2 ) 2 N (LiFSI), lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI), LiBF 4 , LiB (C 2 O 4 ) 2 , LiAsF 6 , LiCIO 4 , LiNO 3 , lithium bis(osalato) borate, LiCF 3 SO 3 , LiN (SO 2 CF 3 ) 2 (LiTFSI), LIN (SO 2 C 2 F 5 ) 2 , LiC(SO 2 CF 3 ) 3 , LiN (SO 3 CF 3 ) 2 , LiC 4 F 9 SO 3 , LiCF 93 SO 3 , LiAlCl 4 , LiSbF 6 , LiF, LiBr, LiCI, LiOH, LiPFSi, and lithium trifluoromethanesulfonate.
7. The solid composite electrolyte according to claim 1 , wherein the at least one ionically non-conductive polymer iii) comprises a polymer selected from the group consisting of vinylidene fluoride (VDF) (co) polymers, styrene-butadiene rubber (SBR), styrene-ethylene-butylene-styrene (SEBS), carboxymethylcellulose (CMC), polyamideimide (PAI), perfluoroalkoxy alkane (PFA), poly(tetrafluoroethylene) (PTFE), poly(acrylonitrile) (PAN) (co) polymers, and polyalkylene oxide (PAO) (co) polymers.
8. The solid composite electrolyte according to claim 1 , wherein an amount of the at least one ionic liquid electrolyte ii) is from 1.0 to 30.0 wt %, based on the total weight of the solid composite electrolyte.
9. The solid composite electrolyte according to claim 1 , wherein an amount of the at least one ionically non-conductive polymer iii) is from 1.0 to 10.0 wt %, based on the total weight of the solid composite electrolyte.
10. A process for manufacturing the solid composite electrolyte according to claim 1 , comprising the steps of
blending the at least one solid inorganic particle i) with the at least one ionic liquid electrolyte ii);
preparing a polymer solution of the at least one ionically non-conductive polymer iii);
mixing said blended solid inorganic particles with the polymer solution;
casting the resulting solid composite electrolyte on a substrate to form a wet film;
drying the wet film; and
calendaring the film.
11. A process for manufacturing the solid composite electrolyte according to claim 1 , comprising the steps of
blending the at least one solid inorganic particle i) with the at least one ionic liquid electrolyte ii);
mixing said blended solid inorganic particles with the at least one ionically non-conductive polymer iii) to obtain a viscous paste; and
calendaring or extruding the viscous paste in successive steps to obtain a solid uniform film,
wherein the at least one ionically non-conductive polymer iii) is in dry state.
12. A solid state battery comprising the solid composite electrolyte according to claim 1 .
13. The solid composite electrolyte of claim 1 , wherein the solid composite electrolyte has an ionic conductivity of at least 1×10 −5 S/cm and the solid composite electrolyte is self-standing and flexible.
14. The solid composite electrolyte according to claim 3 , wherein in the general formula of Li x La y Zr z A w O 12 , A represents one or several dopants selected from the group consisting of Al, Ga, Nb, Fe, Nd, Pt, Ta, W, and mixtures thereof.