Nitrogen-carbon doped modified manganese dioxide composite material and preparation methods thereof

Abstract

The invention relates to a nitrogen-carbon doped modified manganese dioxide composite material and preparation methods thereof. The nitrogen-carbon doped modified manganese dioxide composite materialis equipped with a core-shell structure. A center of the material is porous carbon. An outer surface of the porous carbon is wrapped by an interlayer composed of manganese dioxide nanowires. The outermost layer is a nitrogen-carbon composite layer. A preparation method comprises the steps of preparing ZIF-8 particles; carrying out calcining processing to obtain the porous carbon; loading manganesedioxide to the surface of the porous carbon through hydrothermal reaction; forming a polymer outer layer through autopolymerization of carbon-containing polymeric monomers; and carrying out the calcining processing to obtain a carbon shell with a porous structure. When the nitrogen-carbon doped modified manganese dioxide composite material is taken as a lithium battery material, the nitrogen-carbon doped modified manganese dioxide composite material has relatively high cycling stability and rate capability.

Description

technical field [0001] The invention relates to the technical field of lithium battery materials, in particular to a nitrogen-carbon doped modified manganese dioxide composite material and a preparation method thereof. Background technique [0002] Commercial graphite-based lithium-ion battery anode materials have low theoretical capacity (372mAh / g) and poor electrochemical performance under high current, which limits the cycle capacity and stability of the battery. In order to meet people's demand for high energy density and long cycle life of energy storage devices, manganese dioxide anode materials have emerged. Manganese dioxide has the characteristics of high theoretical specific capacity (1230mAh / g), abundant reserves, and low price, but there are two main problems in the charge and discharge process: first, the manganese dioxide negative electrode material is in the process of repeated charge and discharge. The problem of structural collapse in the lithium intercalat...

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Problems solved by technology

Manganese dioxide has the characteristics of high theoretical specific capacity (1230mAh / g), abundant reserves, and low price, but there are two main problems in the charge and discharge process: first, the manganese dioxide negative electrode material is in the process of repeated charge and discharge. The problem of structural collapse in the lithium intercalation process is that the volume of manganese dioxide particles expands during the lithium intercalation process, resulting in mechanical stress that leads to the powdering of the particles and the failure of electrochemical performance; followed by the dissolution of manganese ions. On the one hand, the dissolution of manganese will reduce The amount of active material in the negative electrode, on the other hand, manganese ions migrate to the surface of the positive electrode to increase the potential and accelerate the loss of the battery

This method effectively disperses manganese dioxide particles and improves the conductivity of the composite material, but the structural design needs to be improved. The outermost layer is manganese dioxide material, which is easy to collapse and fall off during charging and discharging, and the manganese dioxide and Direct contact with the electrolyte is prone to side reactions resulting in failure of electrochemical performance

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