Negative electrode for rechargeable lithium battery, method of preparing same and rechargeable lithium battery including same
A negative electrode for a rechargeable lithium battery, including a negative active material layer including a polymer binder including a repeating unit represented by the following Chemical Formula 1 or the following Chemical Formula 2 and a Si-based negative active material; and a current collector supporting the negative active material layer, is provided: wherein in Chemical Formulae 1 and 2, R 1 and R 2 are the same or different and hydrogen, OH or OOH.
1. A negative electrode for a rechargeable lithium battery, comprising:
a negative active material layer comprising a polymer binder wherein the binder is a copolymer of the repeating units represented by the following Chemical Formula 1 and methylvinyl triethylene glycol; and a composite of Si and C negative active material; and
a current collector supporting the negative active material layer,
wherein the binder is included in an amount of 1 wt % to 10 wt % based on the total weight of the negative active material layer, and
the polymer binder has a weight average molecular weight of 100,000 to 1,000,000:
wherein, R 1 and R 2 are the same or are different, and are hydrogen, OH or OOH.
2. The negative electrode of claim 1 , wherein the composite of Si and C negative active material comprises SiO x (0<x<2), Si, an alloy of Si and Q (wherein, Q is an element selected from the group consisting of an alkali metal, an alkali-earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition element, a rare earth element, and a combination thereof, and not Si), or a combination thereof.
3. The negative electrode of claim 1 , wherein the composite of Si and C comprises:
a crystalline carbon core including pores therein;
an amorphous carbon shell formed on the surface of the core;
Si nano particles dispersed in the pores; and
amorphous carbon present inside the pores.
4. The negative electrode of claim 1 , wherein the polymer binder is a copolymer of polyacrylonitrile and methylvinyl triethylene glycol.
5. The negative electrode of claim 1 , wherein the negative active material layer further comprises a carbon-based negative active material.
6. A rechargeable lithium battery, comprising:
a negative electrode comprising:
a negative active material layer comprising a polymer binder wherein the binder is a copolymer of the repeating units represented by the following Chemical Formula 1 and methylvinyl triethylene glycol; and a composite of Si and C negative active material; and
a current collector supporting the negative active material layer,
wherein the binder is included in an amount of 1 wt % to 10 wt % based on the total weight of the negative active material layer, and
the polymer binder has a weight average molecular weight of 100,000 to 1,000,000:
wherein, R 1 and R 2 are the same or are different, and are hydrogen, OH or OOH;
a positive electrode including a positive active material; and
an electrolyte.
7. A method of negative electrode for a rechargeable lithium battery, comprising:
mixing a polymer binder wherein the binder is a copolymer of the repeating units represented by the following Chemical Formula 1 and methylvinyl triethylene glycol; or includes a repeating unit of the following Chemical Formula 2 and a composite of Si and C negative active material in a solvent to prepare a negative active material composition;
applying the negative active material composition on a current collector; and
heat-treating the current collector applied with the negative active material composition at 80° C. to 160° C.:
wherein, R 1 and R 2 are the same or are different, and are hydrogen, OH or OOH.
8. The method of claim 7 , wherein the heat-treating is performed at 100° C. to 140° C.
9. The method of claim 7 , wherein the heat-treating is performed under a vacuum atmosphere.
10. The method of claim 7 , wherein the composite of Si and C negative active material comprises SiO x (0<x<2), Si, an alloy of Si and Q (wherein, Q is an element selected from the group consisting of an alkali metal, an alkali-earth metal, a Group 13 element, a Group 14 element, a Group 15 element, a Group 16 element, a transition element, a rare earth element, and a combination thereof, and not Si), or a combination thereof.
11. The method of claim 9 , wherein the composite of Si and C comprises
a crystalline carbon core including pores therein;
an amorphous carbon shell formed on the surface of the core;
Si nano particles dispersed in the pore; and
amorphous carbon present inside the pore.
12. The method of claim 7 , wherein during preparing the negative active material composition, a carbon-based negative active material is further added.