Electrode mix for secondary battery, electrode for all-solid-state secondary battery, and all-solid-state secondary battery
Provided is an electrode composite material for a secondary battery that can satisfy both the electronic conductivity and the ionic conductivity at a high level and thus effectively increase the battery characteristics. An electrode composite material for a secondary battery contains a positive-electrode active material and a conductive agent, the positive-electrode active material containing: (i) at least one transition metal element selected from the group consisting of Cr, Fe, Mn, Co, Ni, Ti, and Nb; (ii) at least one element selected from the group consisting of P, Si, and B; and (iii) an element consisting of O, the conductive agent containing a fibrous carbon.
1 . An electrode composite material for a secondary battery, the electrode composite material comprising:
a positive-electrode active material and a conductive agent, wherein
the positive-electrode active material contains: (i) at least one transition metal element selected from the group consisting of Cr, Fe, Mn, Co, Ni, Ti, and Nb; (ii) at least one element selected from the group consisting of P, Si, and B; and (iii) an element consisting of O,
the conductive agent containing a fibrous carbon, and
a ratio of a surface area of the conductive agent to a surface area of the positive-electrode active material (conductive agent/positive-electrode active material) is not less than 0.01 and not more than 0.5.
2 . The electrode composite material for a secondary battery according to claim 1 , wherein the conductive agent consists of the fibrous carbon.
3 . The electrode composite material for a secondary battery according to claim 1 , wherein the fibrous carbon contains carbon nanotubes.
4 . The electrode composite material for a secondary battery according to claim 1 , wherein the fibrous carbon consists of carbon nanotubes.
5 . The electrode composite material for a secondary battery according to claim 1 , wherein the positive-electrode active material contains crystals represented by a general formula A x MC y O z (where A is at least one selected from the group consisting of Li and Na, M is at least one selected from the group consisting of Cr, Fe, Mn, Co and Ni, C is at least one selected from the group consisting of P, Si, and B, 0.2≤x≤4.2, 0.65≤y≤6.5, and 2.5≤z≤20).
6 . The electrode composite material for a secondary battery according to claim 1 , wherein the positive-electrode active material further contains Na.
7 . The electrode composite material for a secondary battery according to claim 1 , wherein said composite material further comprises a solid electrolyte, and, wherein the solid electrolyte contains β-alumina, β″-alumina or NASICON crystals.
8 . The electrode composite material for a secondary battery according to claim 7 , containing, in terms of % by mass, 30% to 98% the positive-electrode active material, 0.1% to 65% solid electrolyte, and 0.1% to 3% the conductive agent.
9 . The electrode composite material for a secondary battery according to claim 1 , wherein a ratio of a content of the conductive agent to a content of the positive-electrode active material (conductive agent/positive-electrode active material) is not less than 0.001 and not more than 0.05 in terms of mass ratio.
10 . The electrode composite material for a secondary battery according to claim 1 , the electrode composite material being for use in a sodium-ion secondary battery.
11 . The electrode composite material for a secondary battery according to claim 1 , the electrode composite material being for use in an all-solid-state sodium-ion secondary battery.
12 . An electrode for an all-solid-state secondary battery, the electrode containing the electrode composite material for a secondary battery according to claim 1 .
13 . An all-solid-state secondary battery comprising as a positive electrode the electrode for an all-solid-state secondary battery according to claim 12 .