Lithium-supplementing slurry for anode, anode and lithium secondary battery

Abstract

The present invention provides a method of supplementing lithium for an anode used for lithium secondary battery. Particularly, the present invention relates to lithium-supplementing slurry and a method for preparing the same, as well as an anode prepared with the slurry and a lithium secondary battery including the same. In the present invention, the prepolymer is used as a binder for supplementing lithium, the process for preparing the prepolymer is easy to operate and has low cost; the lithium-supplementing method using said prepolymer is easy to operate and has low cost, and it is easy to control the amount of lithium supplemented.

Claims

1. A lithium-supplementing slurry for an anode, consisting of a lithium metal powder, a prepolymer and an optional non-aqueous organic solvent, the lithium-supplementing slurry is applied to be coated on the anode which is prepared in advance, a mass ratio of the lithium metal powder and prepolymer is between 2:1 and 1:100, the prepolymer is synthesized from prepolymer monomer through a prepolymerization reaction, the prepolymer monomer is at least one selected from the group consisting of alkyl acrylate, aliphatic alkene, cyanide-containing alkene, polyurethane acrylate and epoxyalkane compounds; a viscosity average molecular weight of the prepolymer is between 500 and 15000; and the optional non-aqueous organic solvent is at least one selected from the group consisting of ester, sulfoxide, amide, ketone, fluoroalkanes and fluoro carbonate.

2. The slurry of claim 1, wherein a mass of prepolymer is 595% of total mass of said slurry.

3. The slurry of claim 1, wherein the mass of the non-aqueous organic solvent is 2089% of total mass of said slurry.

4. The slurry of claim 1, wherein the non-aqueous organic solvent is at least one solvent selected from the group consisting of ethyl acetate, N,N-dimethyl formamide, N,N-dimethyl acetamide, dimethyl sulfoxide, acetone, N-methylpyrrolidone, ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, fluoro n-hexane, fluoro cyclohexane, fluoro ethylene carbonate and propylene carbonate.

5. The slurry of claim 1, wherein the anode comprises an anode active material which is at least one material selected from a carbon based material, a tin based material and a silicon based material.

6. The slurry of claim 5, wherein the carbon based material is at least one selected from the group consisting of natural graphite, artificial graphite, meso-carbon microbeads, amorphous graphite, hard carbon and soft carbon.

7. The slurry of claim 1, wherein the average particle size of the lithium metal powder is less than 200 m.

8. The slurry of claim 1, wherein the prepolymer monomer is at least one selected from the group consisting of methyl methacrylate, and copolymer of methyl methacrylate and acrylonitrile.

9. The slurry of claim 1, wherein the reaction time of prepolymerization is between 0.148 hours.

10. The slurry of claim 1, wherein the prepolymerization is performed at a temperature between 15 C. and 150 C.

11. The slurry of claim 1, wherein an initiator is added during the prepolymerization.

12. The slurry of claim 11, wherein the initiator is at least one selected from the group consisting of 2-hydroxy-2-methylpropiophenone, diphenylmethanone compounds, azo compounds, preoxide compounds and redox compounds.

13. The slurry of claim 12, wherein the initiator is at least one selected from the group consisting of azo-bis-iso-butyronitrile (AIBN), azo-bis-isoheptonitrile, dimethyl azobisisobutyrate (AIBME), hydrogen peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide, methyl ethyl ketone peroxide and diacyl peroxide.

14. The slurry of claim 4, wherein the non-aqueous organic solvent is dimethyl carbonate.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(1) The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

Embodiment 1

(2) Synthesis of prepolymer: conducting a prepolymerization of methyl methacrylate under 5060 C. for 24 hours to obtain a prepolymer of methylmethacrylate; the viscosity average molecular weight of the synthetic prepolymer is between 10003000.

(3) Preparation of electrode plate: Mixing methylmethacrylate prepolymer, lithium metal powder and non-aqueous solvent dimethyl carbonate and stirring to get a colloidal slurry in drying room; coating the colloidal slurry onto a prepared anode, wherein the average diameter D.sub.50 of lithium metal powder tested by LPSA (laser particle size analyzer) is 60 m, the mass of prepolymer is 50 wt % of that of the colloidal slurry, the mass ratio between lithium metal powder and prepolymer is 1:2, and the mass of non-aqueous solvent is 25 wt % of total mass of the colloidal slurry; then carrying on photocuring under UV condition, where polymerization of methylmethacrylate prepolymer takes place at 30 C. with a reaction time of 600 seconds. Finally cold-pressing and yielding an anode.

Embodiment 2

(4) Embodiment 2 is similar to embodiment 1, and the difference is that the prepolymer monomer is copolymer of methyl methacrylate and acrylonitrile during synthesis of prepolymer.

Embodiment 3

(5) Embodiment 3 is similar to embodiment 1, and the difference is that the prepolymer monomer is 4-nitrostyrene, methyl methacrylate and 4-fluorostyrene during synthesis of prepolymer.

Embodiment 4

(6) Embodiment 4 is similar to embodiment 2, and the difference is that during synthesis of prepolymer, the temperature of the prepolymerization is between 5060 C., the reaction time of prepolymerization is between 23 hours, and the viscosity average molecular weight of synthetic prepolymer is between 500010000.

Embodiment 5

(7) Embodiment 5 is similar to embodiment 1, and the difference is that during synthesis of prepolymer, the temperature of the prepolymerization is between 6070 C., and the reaction time of prepolymerization is between 23 hours, the viscosity average molecular weight of synthetic prepolymer is between 2000030000.

Embodiment 6

(8) Embodiment 6 is similar to embodiment 1, and the difference is that during synthesis of prepolymer, the temperature of the prepolymerization is between 7080 C., the reaction time of prepolymerization is between 23 hours, the viscosity average molecular weight of synthetic prepolymer is between 3000040000.

Embodiment 7

(9) Embodiment 7 is similar to embodiment 1, and the difference is that during preparation of electrode plate, prepolymerization is conducted under UV lighting, wherein the reaction time is 15 seconds, the mass ratio of lithium metal powder and prepolymer is 1:20, no non-aqueous solvent is used.

Embodiment 8

(10) Embodiment 8 is similar to embodiment 1, and the difference is that during preparation of electrode plate, prepolymerization is conducted under UV lighting, wherein the reaction time is 7 seconds, the mass ratio of lithium metal powder and prepolymer is 1:4, no non-aqueous solvent is used.

Embodiment 9

(11) Embodiment 9 is similar to embodiment 1, and the difference is that an initiator is introduced into prepolymerization reaction during synthesis of prepolymer, and is also introduced into polymerization reaction during preparation of electrode plate, and said initiator is azo-bis-isobutyronitrile.

Embodiment 10

(12) Embodiment 10 is similar to embodiment 1, and the difference is that an initiator is introduced into polymerization reaction during preparation of electrode plate, and said initiator is benzoyl peroxide and hydrogen peroxide.

Embodiment 11

(13) Embodiment 11 is similar to embodiment 1, the difference is that an initiator is introduced into polymerization reaction during preparation of electrode plate, and said initiator is sodium persulfate and potassium persulfate.

Embodiment 12

(14) Embodiment 12 is similar to embodiment 1, the difference is that the reaction time of the prepolymerization is between 1718 hours, the viscosity average molecular weight of synthetic prepolymer is between 3800050000.

Embodiment 13

(15) Embodiment 13 is similar to embodiment 1, the difference is that during synthesis of prepolymer, the temperature of prepolymerization is between 1530 C. and the reaction time of prepolymerization is between 3540 hours, the viscosity average molecular weight of synthetic prepolymer is between 8001000.

Embodiment 14

(16) Embodiment 14 is similar to embodiment 1, the difference is that during synthesis of prepolymer, the temperature of prepolymerization is between 120150 C. and the reaction time of prepolymerization is between 0.11 hour, the viscosity average molecular weight of synthetic prepolymer is between 80000100000.

Embodiment 15

(17) Embodiment 15 is similar to embodiment 1, the difference is that during preparation of electrode plate, the mass of prepolymer is 90 wt % of the total mass of the colloidal slurry, no non-aqueous solvent is used.

Embodiment 16

(18) Embodiment 16 is similar to embodiment 1, the difference is that during preparation of electrode plate, the mass of prepolymer is 10 wt % of the total mass of the colloidal slurry; and the mass ratio between lithium metal powder and prepolymer is 1:10, the mass of non-aqueous solvent dimethyl carbonate is 89 wt % of the total mass of colloidal slurry.

Embodiment 17

(19) Embodiment 17 is similar to embodiment 1, the difference is that during preparation of electrode plate, the mass of prepolymer is 10 wt % of the total mass of the colloidal slurry; and the mass ratio between lithium metal powder and prepolymer is 2:1, the mass of non-aqueous solvent dimethyl carbonate is 70 wt % of the total mass of colloidal slurry.

Embodiment 18

(20) Embodiment 18 is similar to embodiment 1, the difference is that during preparation of electrode plate, the average diameter D.sub.50 of lithium metal powder tested by LPSA (laser particle size analyzer) is 150 m.