生物质碳/MnO2复合电极材料及其在超级电容器中的应用进展

Progress in biomass-derived carbon materials/MnO2 composite and its application in supercapacitors

近年来,生物质碳材料由于来源广泛、化学稳定性好、比表面积高、环境友好等优点已成为备受关注的电极材料,在能源转化和能量储存领域显示出巨大的应用潜力。但是生物质碳材料的理论比电容有限,且分散性差、机械脆性等缺陷也阻碍了其性能的完全实现,进一步影响了实际比电容。当其用于超级电容器时,受低能的静电作用力驱使,生物质碳材料基超级电容器的能量密度往往较低。将赝电容活性材料MnO2沉积在生物质碳材料基质上,利用生物质碳材料与MnO2的协同效应,可获得电导率、循环稳定性和电化学性能优异的复合材料。在介绍MnO2结构和性质的基础上,对生物质碳材料/MnO2复合电极材料的制备方法展开综合述评。此外,还总结了生物质碳材料/MnO2复合物作为电极材料在超级电容器上的研究进展,并指出了其在应用过程中存在的问题。最后,就生物质碳材料/MnO2复合物在高性能和柔性超级电容器未来应用方面进行分析,认为对生物质碳材料基底的改性、MnO2纳米结构的调控和超级电容器结构的设计优化将是今后的重点研究方向。

In recent years,biomass-derived carbon materials received much attention as electrode materials due to their low cost,good chemical stability,high specific surface area and environmental friendliness.To date,they have shown great potential in electrical energy conversion and storage.However,their theoretical specific capacitance is limited.Besides,the poor dispersion,poor refilling and multi-layer brittleness would hinder their actual applications in supercapacitors.As a result,the supercapacitor devices based on the biomass-derived carbon materials usually suffer from low energy density.An effective way to solve this problem is to deposit the electrochemically active materials,such as MnO2,on biomass-derived carbon materials,including activated carbon,biochar,carbon aerogels and carbon fibers,etc.The biomass-derived carbon materials with abundant pore structures are excellent conductive substrate for the growth of MnO2 crystals.Due to the synergistic effect of biomass-derived carbon materials and MnO2,the composite materials have exhibited excellent conductivity,cyclic stability and electrochemical properties.The preparation methods of biomass-derived carbon materials/MnO2 composite were reviewed and the structure and properties of MnO2 were discussed.In addition,the research progress of biomass-derived carbon materials/MnO2 composites as electrode materials in supercapacitors was also reviewed.Among them,the biomass-derived porous carbon/MnO2 composite showed high conductivity and large specific surface area.The biomass-derived biochar with inherited 3D pore structures and highly porous carbon aerogels are ideal conducive template to grow MnO2 nanocrystals and the obtained carbon/MnO2 composites showed high electrochemical performances.Besides,the flexible carbon fiber/MnO2 composite was considered as excellent electrode materials in wearable supercapacitors.The current challenges in their potential applications were also discussed.Finally,it was put forward the focus and direction of future research of the biomass-derived carbon materials/MnO2 composite electrode materials,including the surface/interface modification of biomass carbon materials,the regulation of MnO2 nanostructure and the optimization of supercapacitor s device structure.