Negative electrode plate, electrochemical apparatus, and electronic apparatus
A negative electrode plate includes a current collector and an active substance layer provided on the current collector, where the active substance layer includes a silicon-based material, and a proportion by mass of element silicon in the active substance layer has a minimum value X1 and a maximum value X2 among different locations of a same area size, where a value of X1/X2 is M, and M≥0.7; and a weight loss rate of the active substance layer under thermogravimetric (TG) analysis within 800° C. has a minimum value Y1 and a maximum value Y2 among different locations of a same area size, where a value of Y1/Y2 is N, and N≥0.7. In this disclosure, the silicon-based material and a binder in the active substance layer are uniformly dispersed, improving C-rate performance and cycling performance of the electrochemical apparatus and reducing swelling of an electrode assembly.
1 . A negative electrode plate, comprising:
a current collector; and
an active substance layer provided on the current collector,
wherein the active substance layer comprises a silicon-based material, and a proportion by mass of element silicon in the active substance layer has a minimum value X1 and a maximum value X2 among different locations of a same area size, wherein a value of X1/X2 is M, and M≥0.7; and
a weight loss rate of the active substance layer under thermogravimetric (TG) analysis within 800° C. has a minimum value Y1 and a maximum value Y2 among different locations of a same area size, wherein N=Y1/Y2, and N≥0.7;
wherein in an X-ray diffraction pattern of the silicon-based material, the highest intensity at 2θ within the range of 20.5°-21.5° is I 1 , and the highest intensity at 2θ within the range of 28.0°-29.0° is I 2 , wherein 0<I 2 /I 1 ≤1.
2 . The negative electrode plate according to claim 1 , wherein a mass percentage of the silicon-based material in the active substance layer is 2%-80%.
3 . The negative electrode plate according to claim 1 , wherein the silicon-based material comprises SiO x , wherein 0.6≤x≤1.5; and/or an average particle size of the silicon-based material is 500 nm-30 μm.
4 . The negative electrode plate according to claim 1 , wherein the silicon-based material comprises at least one of Si, SiO x , a silicon-carbon material or a silicon alloy, wherein a particle size of Si is less than 100 nm, and 0.6≤x≤1.5.
5 . The negative electrode plate according to claim 1 , wherein particle size distribution of the silicon-based material satisfies 0.3≤D n 10/D v 50≤0.6, wherein D n 10 is a particle diameter when a cumulative quantity-of-particles based distribution percentage reaches 10%, which is obtained with a laser scattering particle analyzer, and D v 50 is a particle diameter when a cumulative volume based distribution percentage reaches 50%, which is obtained with a laser scattering particle analyzer.
6 . The negative electrode plate according to claim 1 , wherein the active substance layer further comprises a binder; the binder comprises at least one of carboxymethyl cellulose, polyacrylic acid, polyvinyl pyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, polystyrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene; and a mass percentage of the binder in the active substance layer is 0.5%-10%.
7 . The negative electrode plate according to claim 1 , wherein the active substance layer further comprises a conductive agent;
wherein the conductive agent comprises at least one of single-wall carbon nanotubes, multi-wall carbon nanotubes, vapor grown carbon fiber, conductive carbon black, acetylene black, Ketjen black, conductive graphite, or graphene; and/or a mass percentage of the conductive agent in the active substance layer is 0.1%-5%.
8 . The negative electrode plate according to claim 1 , wherein a mass percentage of the silicon-based material in the active substance layer is 2%-40%.
9 . The negative electrode plate according to claim 1 , wherein a mass percentage of the silicon-based material in the active substance layer is 40%-80%.
10 . The negative electrode plate according to claim 1 , wherein an average particle size of the silicon-based material is 500 nm-10 μm.
11 . An electrochemical apparatus, comprising:
a positive electrode plate;
a negative electrode plate; and
a separator disposed between the positive electrode plate and the negative electrode plate;
wherein the negative electrode plate comprises
a current collector; and
an active substance layer provided on the current collector,
wherein the active substance layer comprises a silicon-based material, and a proportion by mass of element silicon in the active substance layer has a minimum value X1 and a maximum value X2 among different locations of a same area size, wherein a value of X1/X2 is M, and M≥0.7; and
a weight loss rate of the active substance layer under thermogravimetric (TG) analysis within 800° C. has a minimum value Y1 and a maximum value Y2 among different locations of a same area size, wherein N=Y1/Y2, and N≥0.7;
wherein in an X-ray diffraction pattern of the silicon-based material, the highest intensity at 2θ within the range of 20.5°-21.5° is I 1 , and the highest intensity at 2θ within the range of 28.0°-29.0° is I 2 , wherein 0<I 2 /I 1 ≤1.
12 . The electrochemical apparatus according to claim 11 , wherein a mass percentage of the silicon-based material in the active substance layer is 2%-40%.
13 . The electrochemical apparatus according to claim 11 , wherein a mass percentage of the silicon-based material in the active substance layer is 40%-80%.
14 . The electrochemical apparatus according to claim 11 , wherein an average particle size of the silicon-based material is 500 nm-10 μm.
15 . An electronic apparatus, comprising the electrochemical apparatus according to claim 11 .