Method of manufacturing lithium-ion secondary battery electrode
The present invention discloses a method of manufacturing a lithium-ion secondary battery electrode. The method includes the steps of: supplying composite particles ( 1 ), each containing an active material ( 2 ) and a binder ( 4 ), onto a sheet collector ( 42 ); and rolling the composite particles ( 1 ) supplied onto the collector ( 42 ), thus forming an active material layer ( 44 ). The rolling step includes a first rolling sub-step involving first rolling, and a second rolling sub-step to be performed after the first rolling sub-step. Rubber rolls (R 1 ) are preferably used in the first rolling sub-step.
1. A method of manufacturing a lithium-ion secondary battery electrode, the method comprising:
supplying granulated composite particles, each of the composite particles containing an active material and a binder, onto a sheet collector in a powder form; and
rolling the composite particles supplied onto the collector to form an active material layer, wherein
the granulated composite particles are prepared by spray-drying,
the rolling step includes a first rolling sub-step involving first rolling, and a second rolling sub-step to be performed after the first rolling sub-step, and
the first rolling is rubber rolling using a pair of rubber rolls.
2. The method according to claim 1 , further comprising:
flattening the composite particles, supplied onto the collector, using a squeegee, wherein the flattening step precedes the first rolling sub-step.
3. The method according to claim 2 , further comprising:
controlling a vertical position of the squeegee, thus adjusting an amount of the composite particles supplied onto the collector.
4. The method according to claim 1 , wherein rolling is performed more than once in the second rolling sub-step.
5. The method according to claim 1 , wherein at least one of the first rolling sub-step and the second rolling sub-step is heat-rolling.
6. The method according to claim 1 , further comprising: measuring a weight per unit area of the composite particles supplied onto the collector, and adjusting an extent of the rolling in the first rolling sub-step and/or the second rolling sub-step on a basis of the measured weight per unit area, wherein
the measuring and adjusting step is performed at any point between the supplying step and the second rolling sub-step.
7. The method according to claim 1 , wherein the first rolling achieves a first target density of the composite particles, and the second rolling achieves a second target density of the composite particles, and the density of the composite particles is increased by the second rolling sub-step.
8. The method according to claim 7 , wherein the first target density is 110% to 200% relative to an initial density of the composite particles prior to the first rolling sub-step, and the second target density is 240% or less relative to the initial density of the composite particles.
9. The method according to claim 8 , wherein the first target density is 120% to 180% relative to the initial density of the composite particles.
10. The method according to claim 8 , wherein the second target density is 212% or less relative to the initial density of the composite particles.
11. The method according to claim 8 , wherein the second target density is 183% or less relative to the initial density of the composite particles.
12. The method according to claim 8 , wherein the first target density is 110% to 120% relative to the initial density of the composite particles.
13. The method according to claim 12 , wherein the second target density is 183% or less relative to the initial density of the composite particles.
14. The method according to claim 1 , where the second rolling sub-step involves second rolling performed after the first rolling sub-step,
the second rolling is metal rolling using a pair of metal rolls,
the active material layer is not heated before the first rolling sub-step, and
the active material layer is not heated during the first rolling sub-step.