Electrochemical device and electronic device
An electrochemical device includes a negative electrode plate and an electrolyte. The negative electrode plate includes a negative active material. A specific surface area of the negative active material is A m 2 /g and 0.3≤A≤4. The electrolyte includes fluorocarboxylate and fluorocarbonate. Based on a mass of the electrolyte, a mass percent of the fluorocarboxylate is X % and a mass percent of the fluorocarbonate is Y %, 5≤Y≤70, and the electrochemical device satisfies 50≤X+Y≤85, and 6≤Y/A≤200. The synergy between the negative active material and the electrolyte can effectively improve cycle performance of the electrochemical device under high voltages, and alleviate lithium plating of the negative electrode.
1 . An electrochemical device, comprising a negative electrode plate and an electrolyte; wherein the negative electrode plate comprises a negative active material, a specific surface area of the negative active material is A m 2 /g and 0.3≤A≤4; the electrolyte comprises fluorocarboxylate and fluorocarbonate; and, based on a mass of the electrolyte, a mass percent of the fluorocarboxylate is X % and a mass percent of the fluorocarbonate is Y %, 5≤Y≤70, and 55≤X+Y≤85, and 6≤Y/A≤200.
2 . The electrochemical device according to claim 1 , wherein the fluorocarboxylate comprises at least one selected from the group consisting of ethyl difluoroacetate, difluoroethyl acetate, ethyl monofluoroacetate, monofluoroethyl acetate, ethyl trifluoroacetate, and trifluoroethyl acetate.
3 . The electrochemical device according to claim 1 , wherein a number of carbon atoms in the fluorocarbonate is less than or equal to 7, and the fluorocarbonate comprises cyclic fluorocarbonate and/or chain fluorocarbonate.
4 . The electrochemical device according to claim 1 , wherein the fluorocarbonate comprises fluoroethylene carbonate and/or difluoroethylene carbonate.
5 . The electrochemical device according to claim 1 , wherein the fluorocarbonate comprises at least one selected from the group consisting of bis(2,2,2-trifluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, methyl trifluoroethyl carbonate, methyl difluoroethyl carbonate, and methyl-fluoroethyl carbonate.
6 . The electrochemical device according to claim 1 , wherein the electrolyte further comprises a nitrile compound, a number of cyano groups in the nitrile compound is 1 to 6, and, based on the mass of the electrolyte, a mass percent of the nitrile compound is Z %, wherein 0.1≤Z≤10 and 0.5≤Y/Z≤120.
7 . The electrochemical device according to claim 6 , wherein 0.3≤Z≤8 and 5≤Y/Z≤120.
8 . The electrochemical device according to claim 6 , wherein the nitrile compound comprises at least one selected from the group consisting of succinonitrile, adiponitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tri(2-cyanooxy)propane, ethylene glycol bis(propionitrile) ether, and fumaronitrile.
9 . The electrochemical device according to claim 1 , wherein a conductivity of the electrolyte is greater than or equal to 5.5 mS/cm.
10 . The electrochemical device according to claim 1 , wherein the negative active material comprises graphite and/or a silicon-based material.
11 . The electrochemical device according to claim 1 , wherein the negative active material comprises a silicon-based material; and carbon or Me x O y exists on a surface of the silicon-based material, wherein Me comprises at least one selected from the group consisting of Al, Si, Mn, V, Cr, Co, and Zr, 1≤x≤2, and 1≤y≤3.
12 . The electrochemical device according to claim 1 , wherein the electrochemical device further comprises a separator, and the separator satisfies at least one of the following conditions (a) to (c):
(a) an air permeability of the separator is 50 s/100 cm 3 to 700 s/100 cm 3 ;
(b) a thickness of the separator is 5 μm to 30 μm;
(c) a pore size of the separator is greater than 0.005 μm and less than or equal to 1 μm.
13 . The electrochemical device according to claim 12 , wherein at least one surface of the separator is covered with a coating, the coating comprises inorganic particles, and the inorganic particles comprise at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate.
14 . The electrochemical device according to claim 1 , wherein a charge cut-off voltage of the electrochemical device is 4.2 V to 5 V.
15 . An electronic device, comprising an electrochemical device, the electrochemical device comprising a negative electrode plate and an electrolyte; wherein the negative electrode plate comprises a negative active material, a specific surface area of the negative active material is A m 2 /g and 0.3≤A≤4; the electrolyte comprises fluorocarboxylate and fluorocarbonate; and, based on a mass of the electrolyte, a mass percent of the fluorocarboxylate is X % and a mass percent of the fluorocarbonate is Y %, 5≤Y≤70, and 50≤X+Y≤85, and 6≤Y/A≤200.
16 . The electronic device according to claim 15 , wherein the fluorocarboxylate comprises at least one selected from the group consisting of ethyl difluoroacetate, difluoroethyl acetate, ethyl monofluoroacetate, monofluoroethyl acetate, ethyl trifluoroacetate, and trifluoroethyl acetate.
17 . The electronic device according to claim 15 , wherein the fluorocarbonate comprises at least one selected from the group consisting of bis(2,2,2-trifluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, methyl trifluoroethyl carbonate, methyl difluoroethyl carbonate, and methyl-fluoroethyl carbonate.
18 . The electronic device according to claim 15 , wherein the electrolyte further comprises a nitrile compound, a number of cyano groups in the nitrile compound is 1 to 6, and, based on the mass of the electrolyte, a mass percent of the nitrile compound is Z %, wherein 0.1≤Z≤10 and 0.5≤Y/Z≤120;
wherein the nitrile compound comprises at least one selected from the group consisting of succinonitrile, adiponitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tri (2-cyanooxy)propane, ethylene glycol bis(propionitrile) ether, and fumaronitrile.
19 . The electronic device according to claim 15 , wherein a conductivity of the electrolyte is greater than or equal to 5.5 mS/cm.
20 . The electronic device according to claim 15 , wherein the electrochemical device further comprises a separator, and the separator satisfies at least one of the following conditions (a) to (c):
(a) an air permeability of the separator is 50 s/100 cm 3 to 700 s/100 cm 3 ;
(b) a thickness of the separator is 5 μm to 30 μm;
(c) a pore size of the separator is greater than 0.005 μm and less than or equal to 1 μm.