Electrode material containing mixture of polyvinyl alcohol of high degree of polymerization and polyvinyl pyrrolidone as binder and lithium secondary battery employed with the same
An electrode mix comprising a mixture of a polyvinyl alcohol with polyvinyl pyrrolidone as a binder and a lithium secondary battery comprising the same are disclosed. The electrode mix and lithium secondary battery according to the present invention enable stable maintenance of adhesion between active materials and/or adhesion between the active material and current collector and reduction of volumetric changes of anode active materials during repeated charge/discharge cycles, through the use of a polymer having an improved elongation percentage while exhibiting very high adhesive strength, as a binder of an electrode mix. Therefore, the present invention enables production of a large-capacity lithium secondary battery particularly using a silicon- or tin-based anode active material.
1. A lithium secondary battery, comprising a mixture of a polyvinyl alcohol having a polymerization degree of more than 3000 and a saponification degree of more than 80% with polyvinyl pyrrolidone, as a binder,
wherein, the content of polyvinyl pyrrolidone is in the range of 0.1 to 100 parts by weight, based on 100 parts by weight of the polyvinyl alcohol; and
wherein, the content of the binder is in the range of 1 to 50% by weight, based on the total weight of the electrode mix.
2. The lithium secondary battery according to claim 1 , wherein the polyvinyl pyrrolidone has a molecular weight of 1000 to 1,000,000.
3. The lithium secondary battery according to claim 1 , wherein the mix further comprises at least one selected from the group consisting of a cross-linking accelerator, a viscosity adjuster, a conductive material, a filler, a coupling agent, an adhesive accelerator and any combination thereof.
4. The lithium secondary battery according to claim 1 , wherein the binder is used in an anode.
5. The lithium secondary battery according to claim 4 , wherein the anode comprises a carbon-based, silicon-based, tin-based or silicon/carbon-based active material.