Electrode for all-solid-state secondary batteries, all-solid-state secondary battery and method for producing all-solid-state secondary battery
An electrode for all-solid-state secondary batteries which enables the achievement of a practicable all-solid-state secondary battery even if an electrode active material layer does not contain a solid electrolyte which has been an essential ingredient for conventional electrodes for all-solid-state secondary batteries; and a practicable all-solid-state secondary battery which uses an electrode in which an electrode active material layer does not contain a solid electrolyte. The all-solid-state secondary battery includes a positive electrode, a solid electrolyte layer and a negative electrode, the positive electrode and/or the negative electrode has an electrode active material layer on a collector, the electrode active material layer contains an electrode active material and a binder resin; the binder resin contains a polyimide resin; and the electrode active material layer does not contain a solid electrolyte, while containing a lithium salt that has a solubility of 0.1 g or more per 100 g of a solvent at 25° C. with respect to water or at least one organic solvent.
1 . An all-solid-state secondary battery, comprising a positive electrode, a solid electrolyte layer, and a negative electrode, wherein:
the positive electrode and/or the negative electrode has an electrode active material layer that includes an electrode active material and a binder resin, on a current collector, wherein
the binder resin contains a polyimide-based resin, and
the electrode active material layer contains a lithium salt having a solubility in water or at least one organic solvent at 25° C. of 0.1 g/100 g of solvent or more and does not contain a solid electrolyte,
wherein the lithium salt is at least one selected from the group consisting of inorganic lithium salts, perfluoroalkane sulfonates, LiN(FSO 2 ) 2 , perfluoroalkane sulfonylimide salts, perfluoroalkane sulfonylmethides, fluoroalkyl fluoride phosphates, and oxalatoborate salts,
wherein the solid electrolyte layer comprises a polymer solid electrolyte, wherein the polymer solid electrolyte is at least one selected from the group consisting of a polyethylene oxide-based polymer, polypropylene oxide-based polymer, perfluorocarbon sulfonic acid-based polymer, sulfonated polyetheretherketone, sulfonated polyethersulfone, and other aromatic hydrocarbon polymer electrolyte having an ionic group.
2 . The all-solid-state secondary battery according to claim 1 , wherein the electrode active material layer further comprises a conductive auxiliary agent.
3 . The all-solid-state secondary battery according to claim 1 , wherein the lithium salt has an ionic conductivity at 25° C. of 1×10 −4 S/cm or more.
4 . The all-solid-state secondary battery according to claim 1 , wherein the lithium salt is LiN(FSO 2 ) 2 or a perfluoroalkane sulfonylimide salt or both.
5 . The all-solid-state secondary battery according to claim 1 , wherein the lithium salt is at least one selected from the group consisting of LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 , LiN(CF 3 CF 2 SO 2 ) 2 , and LiN(CF 3 SO 2 )(C 4 F 9 SO 2 ).
6 . A method for producing an all-solid-state secondary battery, comprising:
preparing an electrode sheet having, on a current collector, an electrode active material layer that contains an electrode active material, a polyimide-based resin as a binder resin, and a lithium salt having a solubility in water or at least one organic solvent at 25° C. of 0.1 g/100 g of solvent or more and does not contain a solid electrolyte,
wherein the lithium salt is at least one selected from the group consisting of inorganic lithium salts, perfluoroalkane sulfonates, LiN(FSO 2 ) 2 , perfluoroalkane sulfonylimide salts, perfluoroalkane sulfonylmethides, fluoroalkyl fluoride phosphates, and oxalatoborate salts;
laminating and integrating the electrode sheet, a solid electrolyte-containing sheet that contains a solid electrolyte, and a counter electrode sheet,
wherein the solid-electrolyte-containing sheet is a layer comprising a polymer solid electrolyte, wherein the polymer solid electrolyte is at least one selected from the group consisting of a polyethylene oxide-based polymer, polypropylene oxide-based polymer, perfluorocarbon sulfonic acid-based polymer, sulfonated polyetheretherketone, sulfonated polyethersulfone, and other aromatic hydrocarbon polymer electrolyte having an ionic group.
7 . The method for producing an all-solid-state secondary battery according to claim 6 , wherein
preparing the electrode sheet includes:
applying, on the current collector, an electrode mixture paste that includes the electrode active material, the polyimide-based resin or a precursor thereof as the binder resin, the lithium salt having the solubility in water or at least one organic solvent at 25° C. of 0.1 g/100 g of solvent or more, and a solvent and does not include a solid electrolyte; and
drying or heat-treating the electrode mixture paste to form the electrode active material layer.
8 . The method for producing an all-solid-state secondary battery according to claim 6 , wherein the electrode sheet, the solid electrolyte-containing sheet, and the counter electrode sheet are laminated and integrated by using a dry process.
9 . An all-solid-state secondary battery according to claim 1 , wherein the lithium salt has a solubility in water or at least one organic solvent at 25° C. of 10 g/100 g of solvent or more.