Structure of multi-sphere carbon-coated manganese dioxide composite material and preparation method thereof

Abstract

The invention relates to a structure of a multi-sphere carbon-coated manganese dioxide composite material. Carbon-coated manganese dioxide has a submicron spherical shape and is formed by the multi-sphere three-dimensional stacking of a graphitized carbon material coated on the surface of the manganese dioxide, a conductive material and a three-dimensional framework material. A manganese oxide precursor material is any one or a mixture of alpha-MnO2, beta-MnO2 and electrolytic manganese dioxide. The conductive material is any one or a mixture of activated carbon, acetylene black, and graphite.A carbon-coated precursor is any one or a mixture of glucose, sucrose and citric acid. The three-dimensional framework material is any one or a mixture of carbon nanotubes, carbon fibers and graphenesheets. A dispersing agent is any one or a mixture of polyacrylic acid and sodium lauryl sulfate. The invention has the advantages that the synthesis process is simple, the requirements for equipmentparameters are low, the effective three-dimensional multi-sphere carbon coating can be formed on the surface of the manganese dioxide, and the electrical conductivity and electrochemical stability ofthe material are improved.

Description

technical field [0001] The invention belongs to the technical field of neutral zinc-manganese batteries, and in particular relates to a structure and a preparation method of a multi-sphere stacked carbon-coated manganese dioxide composite material. Background technique [0002] With the increasingly prominent issues of energy and environment, the demand for clean energy and large-scale energy storage technology continues to grow, which puts forward higher requirements on the energy density and cycle stability of energy storage materials. Aqueous zinc-ion battery is a new type of green and environment-friendly battery energy storage system that has gradually emerged in recent years. It uses low-cost, high-capacity metal zinc as the negative electrode of the battery, and the electrolyte is an aqueous solution of zinc ions, which is safe and non-toxic. Manganese dioxide has a unique three-dimensional pore structure and excellent electrochemical zinc storage properties, so it ha...

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Problems solved by technology

[0003] However, due to the poor conductivity of the manganese dioxide material itself, the charge-discharge rate characteristics are poor when applied to zinc-ion batteries. In order to improve this deficiency, Sun et al. (Journal of the American Chemical Society, 2017, 139, 9775-9778) adopted The manganese dioxide composite material with carbon fiber cloth as the conductive substrate was prepared by electrodeposition method, and the aqueous zinc ion battery was assembled, and the specific capacity could reach 290mAh g at the charge and discharge rate of 0.3C -1 , the reversible cycle can reach 10,000 cycles at a high rate of 6.5C, and the Coulombic efficiency can reach 100%, but the preparation method is cumbersome, it is difficult to prepare in batches, and the cost of carbon fiber cloth is high, which limits the industrialization of this material application

Wu et al. (Small, 2018, 1703850) added graphene oxide while preparing manganese dioxide by hydrothermal method, and prepared graphene-coated manganese dioxide nanowires by controlling the hydrothermal temperature and time. The conductivity of manganese material improves the electrochemical stability of the material at the same time, it is applied to the positive electrode material of zinc ion battery, and the specific capacity can reach 382.2mAh g -1 , at 3A g -1 The reversible cycle can reach 3000 cycles at a large rate, and the capacity retention rate is higher than 94%. However, due to the high temperature and high pressure hydrothermal environment required in the preparation process, graphene with a high price and cost needs to be added, and the yield is low. still doesn't work with batch compositing

Liu Weiliang et al. (CN107706405 A) used conductive polymer materials with good electrical conductivity to improve the performance of manganese dioxide materials in water-based zinc batteries, cross-linked into networks through initiators in the process of synthesizing manganese dioxide, and carbonized A nitrogen or nitrogen-sulfur-doped carbon-coated manganese dioxide composite material was prepared by the process, which achieved a good application effect, but because the carbon source used was toxic organic substances such as pyrrole, aniline, and thiophene, it could not be environmentally friendly. requirements, the bulk density of the product is low and the cost is high, so there are still big obstacles in industrial application

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