Preparation method of lithium iron phosphate/expanded graphite composite electrode material and preparation method of lithium ion capacitor made of material

Abstract

The invention provides a preparation method of a lithium iron phosphate/expanded graphite composite electrode material and a preparation method of a lithium ion capacitor made of the material, and relates to a preparation method of a lithium ion capacitor anode material and a preparation method of a lithium ion capacitor. The preparation methods overcome defects that the safety performance is poor, the cost and environmental pollution are high, lithium iron phosphate cannot be composited with graphite or graphene effectively to utilize excellent electrochemical properties of the graphite or the graphene. The preparation method of the composite electrode material comprises the steps of dissolving a phosphorus source, an iron source and a lithium source in H2O to prepare a lithium iron phosphate precursor, expanding the expandable graphite in a muffle furnace, preparing a lithium iron phosphate/expanded graphite composite precursor through mechanical mixing and ultrasonic treatment of the lithium iron phosphate precursor and the expandable graphite, and carbonizing to obtain the composite electrode material. The preparation method of the lithium ion capacitor comprises the steps of preparing the composite electrode material into an electrode plate to serve as an anode, mixing activated carbon and the graphite to prepare an electrode plate to serve as a cathode, sandwiching a polypropylene membrane between the anode and the cathode, and injecting an inorganic lithium salt aqueous solution as an electrolyte. An in-situ sol-gel composite method increases the utilization ratio of an active substance of the lithium iron phosphate, reduces the internal resistance of the material, and is simple to operate.

Description

technical field [0001] The invention relates to a preparation method of the positive electrode material of the lithium ion capacitor, and also relates to a preparation method of the lithium ion capacitor. Background technique [0002] Lithium-ion capacitors have both high energy density and high power density, and are a new generation of energy storage devices. However, the existing lithium-ion capacitors mainly use organic solvents as electrolytes, causing pollution to the environment, and their safety cannot be guaranteed. [0003] As an ideal positive electrode material for lithium ion capacitors, lithium iron phosphate has the advantages of high specific capacity and stable structure. However, the shortcomings of lithium iron phosphate, such as large internal resistance and low lithium ion migration rate, have become a bottleneck in the application of lithium iron phosphate. The modification of lithium iron phosphate by carbon coating is the most widely used modificatio...

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Problems solved by technology

[0005] The invention provides a preparation method of a lithium iron phosphate / expanded graphite composite electrode material and a preparation method of a lithium ion capacitor using the material, so as to solve the problem of low safety performance, large environmental pollution, high cost and inability to effectively combine with graphite in the prior art. or graphene composites to take full advantage of its excellent electrochemical properties

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