Cobalt disulfide/sulfide solid electrolyte composite positive electrode material coated with carbon nanotubes, and preparation method and application thereof

Abstract

The invention discloses a cobalt disulfide / sulfide solid electrolyte composite positive electrode material coated with carbon nanotubes, and a preparation method and an application thereof. The preparation method comprises the following steps: adding cobalt nitrate hexahydrate, anhydrous dextrose and melamine into deionized water, ultrasonically dispersing, then heating and stirring, and transferring into a drying oven for drying; placing a dried product in a tubular furnace filled with argon for high-temperature carbonization, and jointly calcining the carbonized product and thiourea to obtain a cobalt disulfide material coated with carbon nanotubes; and putting the vulcanized product, quantitative lithium sulfide and quantitative phosphorus pentasulfide into an anhydrous acetonitrile solvent, heating, stirring, and sintering at a high temperature to obtain the sulfide solid electrolyte and carbon-nanotube-coated cobalt disulfide composite positive electrode material. According to the prepared positive electrode material, the cobalt disulfide is uniformly coated with the carbon nanotubes in morphology, the carbon nanotubes are uniformly coated with the sulfide solid electrolyte, and meanwhile, a relatively high specific capacity and stable cycle performance are possessed.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for solid-state batteries; the invention specifically relates to a carbon nanotube-coated cobalt disulfide / sulfide solid electrolyte composite positive electrode material and a preparation method and application thereof. Background technique [0002] Lithium-ion batteries are widely used as power sources in various fields such as portable electronic devices and electric vehicles due to their high energy density, light weight, and long cycle life. However, the traditionally used liquid electrolytes have safety hazards such as flammability and leakage, which hinder the further development of lithium-ion batteries. All-solid-state batteries, which use solid-state electrolytes with good thermal stability and mechanical strength, as well as high ionic conductivity, are considered to be the ultimate solution to these safety issues. As an inorganic solid electrolyte, the sulfide sol...

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Problems solved by technology

However, the interfacial compatibility and stability between electrodes and sulfide solid-state electrolytes seriously affect the performance of all-solid-state batteries.

For the positive electrode side interface, when using a transition metal oxide positive electrode (lithium cobaltate, lithium manganate, lithium nickel cobalt aluminate, lithium nickel cobalt manganate, etc.), there is a space charge layer between the electrode and the sulfide electrolyte, resulting in The interface resistance increases, causing the battery capacity to decline sharply until failure

For example, the lithium manganate positive electrode material reported on Chem.Mater.2016, 28, 2634-2640, the capacity of the battery assembled with the sulfide electrolyte is only 89mAh / g in the first cycle, and the capacity after 10 cycles is only 45mAh / g, indicating that When this cathode material is matched with a sulfide solid electrolyte, the capacity is extremely low and the capacity fades rapidly due to interface instability.

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