Li-ion supercapacitor

Abstract

The invention provides a Li-ion supercapacitor. The active material of a positive plate of the Li-ion supercapacitor comprises a porous carbon material and LiNixCoyMnzO2; the porous carbon material is at least one of active carbon, an active carbon fiber, porous graphitized carbon black and graphene; the ratio of the porous carbon material to LiNixCoyMnzO2 is (1:1)-(1:4), wherein x+y+z=1, x:y:z=5:2:3 or x:y:z=5:3:2 or x:y:z=6:2:2 or x:y:z=7:1.5:1.5 or x:y:z=8:1:1; the active material of a negative plate is at least one of synthetic graphite, interphase graphite, mesocarbon microbeads, hard carbon and soft carbon; the mass ratio of the LiNixCoyMnzO2 contained in the positive plate to the active material contained in the negative plate is 0.5-1.6; the electrolyte of the Li-ion supercapacitor consists of an electrolyte salt and an organic solvent; the electrolyte salt is selected from LiPF6 or LiBF4 or LiBOB or LiFSI; and the organic solvent is at lest one of ethylene carbonate, carbonic allyl ester, carbonic methyl ester, methyl carbonate, diethyl carbonate and acetonitrile.

Description

technical field [0001] The invention relates to an electrochemical capacitor, in particular to a lithium ion supercapacitor. Background technique [0002] Supercapacitor, also known as electrochemical capacitor, is a new type of energy storage element. It is between traditional capacitors and secondary batteries. Its capacity is much larger than traditional capacitors, and its high-rate charge and discharge performance is far superior to secondary batteries. . Supercapacitors can generally be divided into three types: one is an electric double layer capacitor (EDLC) that uses the principle of an electric double layer at the interface between electrodes and electrolytes to physically store charges, and the other uses the principle of rapid oxidation-reduction reactions on the surface of electrode materials to store charges. Pseudocapacitor (or quasi-capacitor, Pseudocapacitor) of charge, and a hybrid capacitor (Hybrid Capacitor) that combines electric double layer capacitanc...

AI Technical Summary

Problems solved by technology

Due to the low electrochemical potential of lithium iron phosphate, the voltage window (the voltage window is only 2.0~3.8V) and energy density of lithium-ion supercapacitors are limited; at the same time, the pre-embedded lithium process is more complicated, which increases the process cost

Wu Mingxia and others reported a hybrid supercapacitor ("Electronic Components and Materials", Vol. 30, No. 1, 2011, pp. 34-37), which uses LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 As the active material of the positive electrode, activated carbon is used as the active material of the negative electrode. Since the specific surface area of ​​the activated carbon is very large and the solid electrolyte interphase (Solid Electrolyte Interphase, SEI) generated on its surface is unstable, it will consume a large amount of lithium ions, so provide LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 The material must be very excessive, and the positive and negative electrode capacity ratio can reach 4:1 to have a good effect. However, LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 The price of the material is expensive, and it is obviously uneconomical to use an excessive amount of positive electrode active material