Electrolyte solution for alkali metal-sulfur-based secondary battery, and alkali metal-sulfur-based secondary battery
An electrolyte solution for an alkali metal-sulfur-based secondary battery, an alkali metal-sulfur-based secondary battery, and a module containing the alkali metal-sulfur-based secondary battery. The electrolyte solution includes a positive electrode containing a carbon composite material that contains a carbon material and a sulfur-containing positive electrode active material. The carbon material has a pore volume ratio (micropores/mesopores) of 1.5 or higher. The electrolyte solution contains a fluorinated ether represented by the following formula (1): R 11 —(OR 12 ) n11 —O—R 13 . In the formula, R 11 and R 13 are the same as or different from each other, and are each an alkyl group optionally containing a fluorine atom, with at least one of R 11 or R 13 containing a fluorine atom; R 12 is an alkylene group optionally containing a fluorine atom; and n11 is 0, 1, or 2.
1. An alkali metal-sulfur-based secondary battery comprising a positive electrode, a negative electrode, and an electrolyte solution,
the positive electrode containing a carbon composite material that contains a carbon material having a pore volume ratio (micropores/mesopores) of 1.5 to 3.0, and a sulfur-containing positive electrode active material containing simple sulfur,
the electrolyte solution containing a fluorinated ether represented by the following formula (1):
R 11 —(OR 12 ) n11 —O—R 13
wherein R 11 and R 13 are the same as or different from each other, and are each an alkyl group optionally containing a fluorine atom, with at least one of R 11 or R 13 containing a fluorine atom; R 12 is an alkylene group optionally containing a fluorine atom; and n11 is 0, 1, or 2,
wherein the electrolyte solution further contains at least one selected from the group consisting of a fluorinated saturated cyclic carbonate, a fluorinated acyclic carbonate, and a fluorinated ester,
the fluorinated saturated cyclic carbonate is represented by the following formula (2):
wherein R 21 to R 24 are the same as or different from each other, and are each —H, —CH 3 , —F, a fluorinated alkyl group optionally containing an ether bond, or a fluorinated alkoxy group optionally containing an ether bond, with at least one of R 21 to R 24 being —F, a fluorinated alkyl group optionally containing an ether bond, or a fluorinated alkoxy group optionally containing an ether bond,
the fluorinated acyclic carbonate is represented by the following formula (3):
wherein R 31 and R 32 are the same as or different from each other, and are each an alkyl group optionally containing an ether bond and optionally containing a fluorine atom, with at least one of R 31 or R 32 containing a fluorine atom, and
the fluorinated ester is represented by the following formula (4):
wherein R 41 and R 42 are the same as or different from each other, are each an alkyl group optionally containing an ether bond and optionally containing a fluorine atom, and optionally bind to each other to form a ring, with at least one of R 41 or R 42 containing a fluorine atom,
wherein the alkali metal-sulfur-based secondary battery exhibits a single main discharge plateau on and after the second cycle, and a reaction accompanied by Li 2 S 8 represents 5% or less of all discharge reactions.
2. A module comprising the alkali metal-sulfur-based secondary battery according to claim 1 .
3. An alkali metal-sulfur-based secondary battery comprising a positive electrode, a negative electrode, and an electrolyte solution,
the positive electrode containing a carbon composite material that contains a carbon material having a pore volume ratio (micropores/mesopores) of 1.5 to 3.0, and a sulfur-containing positive electrode active material,
the electrolyte solution containing a fluorinated ether represented by the following formula (1):
R 11 —(OR 12 ) n11 —O—R 13
wherein R 11 and R 13 are the same as or different from each other, and are each an alkyl group optionally containing a fluorine atom, with at least one of R 11 or R 13 containing a fluorine atom; R 12 is an alkylene group optionally containing a fluorine atom; and n11 is 0, 1, or 2,
wherein the electrolyte solution further contains at least one selected from the group consisting of a fluorinated saturated cyclic carbonate, a fluorinated acyclic carbonate, and a fluorinated ester,
the fluorinated saturated cyclic carbonate is represented by the following formula (2):
wherein R 21 to R 24 are the same as or different from each other, and are each —H, —CH 3 , —F, a fluorinated alkyl group optionally containing an ether bond, or a fluorinated alkoxy group optionally containing an ether bond, with at least one of R 21 to R 24 being —F, a fluorinated alkyl group optionally containing an ether bond, or a fluorinated alkoxy group optionally containing an ether bond,
the fluorinated acyclic carbonate is represented by the following formula (3):
wherein R 31 and R 32 are the same as or different from each other, and are each an alkyl group optionally containing an ether bond and optionally containing a fluorine atom, with at least one of R 31 or R 32 containing a fluorine atom, and
the fluorinated ester is represented by the following formula (4):
wherein R 41 and R 42 are the same as or different from each other, are each an alkyl group optionally containing an ether bond and optionally containing a fluorine atom, and optionally bind to each other to form a ring, with at least one of R 41 or R 42 containing a fluorine atom,
wherein the alkali metal-sulfur-based secondary battery exhibits a single main discharge plateau on and after the second cycle, and a reaction accompanied by Li 2 S 8 represents 5% or less of all discharge reactions.
4. A module comprising the alkali metal-sulfur-based secondary battery according to claim 3 .