Method of manufacturing positive electrode for all-solid-state batteries and positive electrode for all-solid-state batteries manufactured using the same
A method of manufacturing a positive electrode for sulfide-based all-solid-state batteries, including: preparing a slurry, coating the slurry on a current collector, and then drying. The slurry is prepared by a method including the steps of a) mixing a positive electrode active material and a solid electrolyte in a dry state; b) adding a conducting agent to the mixture of step a) and mixing in a dry state; and c) adding a binder and a solvent to the mixture of step b) and mixing in a wet state.
1. A method of manufacturing a positive electrode for sulfide-based all-solid-state batteries, comprising:
preparing a slurry, wherein the slurry is prepared by:
a) mixing a positive electrode active material and a solid electrolyte in a first dry state;
b) adding a conducting agent to the mixture of the step a) and mixing in a second dry state;
c) adding a first portion of a binder and a solvent to the mixture of the step b) and mixing in a first wet state, and
d) adding a liquid in which an additional conducting agent and a second portion of the binder are pre-dispersed to the wet mixture of the step c) and mixing in a second wet state,
coating the slurry on a current collector, and then drying.
2. The method according to claim 1 , further comprising adding an additional solid electrolyte between the steps b) and c) and mixing in a third dry state.
3. The method according to claim 1 , wherein a particle size of the solid electrolyte is different in each mixing step.
4. The method according to claim 1 , wherein the step a) comprises controlling an amount of the solid electrolyte so that the solid electrolyte is coated in less than 100% of a surface area of the positive electrode active material in a single layer.
5. The method according to claim 1 , further comprising step e) below after the step d):
e) adding a third portion of the binder to the wet mixture of the step d) and mixing in a third wet state.
6. The method according to claim 1 , wherein
the conducting agent of the step b) is 10 to 50% of a total amount of conducting agent used in manufacturing the positive electrode, and
the conducting agent of the step d) is 50 to 90% of a total amount of conducting agent used in manufacturing the positive electrode.
7. The method according to claim 1 , wherein a weight ratio of a total positive electrode active material, a total solid electrolyte, a total conducting agent, and a total binder used in the positive electrode for sulfide-based all-solid-state batteries is 50 to 80:10 to 30:1 to 20:1 to 20.
8. The method according to claim 1 , wherein the positive electrode active material is a sulfur-carbon composite electrode active material comprising a porous carbon material, a compound having electrolyte impregnation properties, and sulfur, wherein the sulfur-carbon composite electrode active material includes a coating layer in which at least one of an inner surface or an outer surface of the porous carbon material includes the compound having electrolyte impregnation properties.
9. A positive electrode for sulfide-based all-solid-state batteries manufactured by the method according to claim 1 .
10. The positive electrode for sulfide-based all-solid-state batteries according to claim 9 , wherein an electric resistance (surface resistance) is 400 mΩ/sq or less, and an ion conductivity is 2×10 −3 or more to 7×10 −5 (S/cm) or less.
11. An all-solid-state battery comprising the positive electrode for sulfide-based all-solid-state batteries according to claim 9 .