Carbon-based electrode material having super high specific capacitance and combined electrode material thereof

Abstract

The invention relates to a carbon-based electrode material having super high specific capacitance and a combined electrode material thereof. Capacitance of the carbon-based electrode material comprises two parts, including double-electric-layer capacitance and Faradaic pseudo capacitance, the double-electric-layer capacitance is 20-60% of the capacitance of the carbon-based electrode material, the specific capacitance of the carbon-based electrode material under the 1A / g current density is more than 400, the volume specific capacitance is more than 300 F / ml, the energy density of a symmetric device of a water-based electrolyte is more than 20 Wh / kg, and the volume energy density is more than 15Wh / kg.

Description

technical field [0001] The invention relates to a carbon-based electrode material with an ultrahigh specific capacitance and a composite electrode material thereof, belonging to the technical fields of materials and electrochemistry. Background technique [0002] Supercapacitors have the characteristics of high power density, long cycle life, safety and reliability, and can be widely used in hybrid electric vehicles, high-power output equipment, etc. At present, supercapacitors have formed a very considerable market size in the world, with an output value of 470 million US dollars in 2010, and a growth rate of nearly 20% in recent years. Although the supercapacitor industry has outstanding prospects, it is limited by the low energy density (conventional activated carbon supercapacitor mass specific capacitance <200F / g, volume specific capacitance <200F / mL, energy density <10Wh / kg), which is far lower than lithium batteries ( >100Wh / kg), which makes large-scale a...

AI Technical Summary

Problems solved by technology

However, this type of material reported in the literature has two fatal problems: one is that the introduction of doping elements will significantly reduce the conductivity of the material; the other is that the proportion of Faraday capacitance produced by doping elements is very low (typically less than 10% ), the main reason is that there are a large number of doping active centers that cannot be effectively utilized

Although Faraday capacitors (such as polymers, transition metal oxides, etc.) can obtain high specific capacitance through redox reactions during charge and discharge, they are poor in stability (capacitance retention is less than 50% after five thousand cycles), Low power density (less than 1 kilowatt per kilogram), which limits the practical application of Faraday capacitors

Moreover, after the electrode material with Faraday capacitance is made into a supercapacitor device, due to the difference in the voltage of the positive and negative poles, the redox potential cannot be reached at the same time, and the energy storage characteristics of the super electrode material cannot be fully displayed.

Currently, capacitive devices based on surface redox reactions of metal compounds or conductive polymers lose more than 15% of their specific capacitance

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