Method of reusing positive electrode material
The present invention relates to a method of reusing a positive electrode material, and more particularly, the method includes: inputting a positive electrode for a lithium secondary battery comprising a current collector, and a positive electrode active material layer formed on the current collector and including a first positive electrode active material, a first binder and a first conducting agent, into a solvent; separating at least a portion of the positive electrode active material layer from the current collector; adding second binder powder to the solvent and performing primary mixing a resulting mixture; and preparing a positive electrode material slurry by adding a second positive electrode active material and a second conducting agent to the solvent and performing secondary mixing a resulting mixture.
1. A method of reusing a positive electrode material, comprising:
inputting a positive electrode for a lithium secondary battery comprising a current collector, and a positive electrode active material layer formed on the current collector and including a first positive electrode active material, a first binder and a first conducting agent, into a solvent;
separating at least a portion of the positive electrode active material layer from the current collector in the solvent;
adding a second binder powder to the solvent and performing primary mixing on a first resulting mixture, wherein, during the primary mixing, the separated positive electrode active material layer is pulverized and separated into the first positive electrode active material, the first binder and the first conducting agent and the second binder powder is mixed with the first positive electrode active material, the first binder and the first conducting agent in the solvent; and
preparing a positive electrode material slurry by adding a second positive electrode active material and a second conducting agent to the solvent and performing secondary mixing on a second resulting mixture,
wherein a ratio of a total weight of the first positive electrode active material, the first binder and the first conducting agent, which are included in a separated positive electrode active material layer, to a total weight of the second positive electrode active material, the second binder powder and the second conducting agent ranges from 8:92 to 28:72, and
wherein a total weight of the first positive electrode active material, the first binder, the first conducting agent, the second positive electrode active material, the second binder powder and the second conducting agent is 2.25 to 6 fold a solvent weight.
2. The method according to claim 1 , wherein at least a portion of the positive electrode active material layer is separated from the current collector through ultrasonication.
3. The method according to claim 2 , wherein the ultrasonication is performed for 5 to 60 minutes.
4. The method according to claim 1 , wherein the positive electrode for a lithium secondary battery is not subjected to a charge/discharge cycle process.
5. The method according to claim 1 , wherein the solvent is N-methyl-2-pyrrolidone.
6. The method according to claim 1 , wherein the second binder powder has an average particle size (D 50 ) of 100 to 300 μm.
7. The method according to claim 1 , further comprising, after separating at least the portion of the positive electrode active material layer from the current collector, removing the current collector from the solvent.
8. The method according to claim 1 , wherein 70 wt % or more of the positive electrode active material layer is separated from the current collector.
9. The method according to claim 1 , wherein a weight of the separated positive electrode active material layer is 0.25 to 0.75 fold the solvent weight.
10. The method according to claim 1 , wherein the primary mixing is performed for 30 to 600 minutes.
11. The method according to claim 1 , wherein the secondary mixing is performed for 30 to 240 minutes.
12. The method according to claim 1 , wherein, in the adding, the second binder powder is disposed and dissolved uniformly in the solvent.
13. The method according to claim 1 , wherein the second binder powder is an identical material to a material of the first binder.
14. The method according to claim 1 , wherein the second binder powder is different from the first binder.
15. The method according to claim 1 , wherein the second binder powder is added to the solvent at 0.5 to 30 wt %.
16. The method according to claim 1 , wherein the second positive electrode active material is added at 80 to 99 wt % with respect to the total weight of the second positive electrode active material, the second binder powder and the second conductive agent.
17. The method according to claim 1 , wherein the ratio of the total weight of the first positive electrode active material, the first binder and the first conducting agent, which are included in the separated positive electrode active material layer, to the total weight of the second positive electrode active material, the second binder powder and the second conducting agent ranges from 10:90 to 25:75.