Negative electrode for secondary battery

1 . A negative electrode for a secondary battery comprising:

a carbon-based active material;

a conductive material;

a silicon-based active material-polymer binder combination comprising a silicon-based active material, and a polymer binder bonded to a surface of the silicon-based active material, wherein the polymer binder suppresses expansion of the silicon-based active material; and

a water-based binder,

wherein the polymer binder is included in an amount of 33 to 45 wt % based on a weight of the silicon-based active material, and

a ratio of a weight percentage of the polymer binder to a weight percentage of the silicon-based active material is 25.3% or greater and 43.5% or less.

2 . The negative electrode for a secondary battery of claim 1 , wherein the silicon-based active material is included in an amount of 5 to 25 wt % based on a total weight of active material including the carbon-based active material and the silicon-based active material.

3 . The negative electrode for a secondary battery of claim 1 , wherein the polymer binder comprises a hydrophilic polymer material having a hydroxy group (—OH).

4 . The negative electrode for a secondary battery of claim 1 , wherein the polymer binder comprises at least one of polyacrylic acid (PAA), polyvinyl alcohol (PVA), or sodium-polyacrylate (Na-PA).

5 . The negative electrode for a secondary battery of claim 4 , wherein the water-based binder comprises a rubber-based material.

6 . The negative electrode for a secondary battery of claim 1 , wherein the water-based binder is included in an amount of 30 to 40 wt % based on a weight of the polymer binder.

7 . The negative electrode for a secondary battery of claim 1 , wherein the water-based binder comprises a rubber-based material.

8 . The negative electrode for a secondary battery of claim 1 , wherein the water-based binder comprises at least one of styrene butadiene rubber (SBR), acrylonitrile butadiene rubber, acrylic rubber, butyl rubber, or fluoro rubber.

9 . A secondary battery comprising the negative electrode of claim 1 , said secondary battery having a discharge capacity retention rate of 90% or greater up to a fifth cycle under conditions of charging at 0.5 C and discharging at 0.5 C.

10 . The negative electrode for a secondary battery of claim 1 , wherein the polymer binder is adsorbed to the surface of the silicon-based active material.

11 . The negative electrode for a secondary battery of claim 1 , wherein the polymer binder is a hydrophilic polymer binder having a plurality of hydroxy groups selectively adsorbed to the surface of the silicon-based active material.

12 . The negative electrode for a secondary battery of claim 1 , wherein the polymer binder is a hydrophilic polymer binder having a plurality of hydroxy groups, and

wherein the silicon-based active material-polymer binder combination is formed by preparing a pre-dispersion slurry in which the hydrophilic polymer binder having the plurality of hydroxy groups is selectively adsorbed to a hydrophilic particle surface of the silicon-based active material.

13 . The negative electrode for a secondary battery of claim 1 , wherein a ratio of a weight percentage of the conductive material to a weight percentage of the silicon-based active material is 5.3% or greater.

14 . The negative electrode for a secondary battery of claim 1 , wherein the silicon-based active material is included in an amount of 5 to 25 wt % based on a total weight of active material including the carbon-based active material and the silicon-based active material, and

the water-based binder is included in an amount of 30 to 40 wt % based on a weight of the polymer binder.

15 . The negative electrode for a secondary battery of claim 1 , wherein the ratio of the weight percentage of the polymer binder to the weight percentage of the silicon-based active material is 25.3% or greater and 33.8% or less.