电化学诱导表面引发聚合技术在电极/溶液界面处构筑功能性聚合物刷及高能量密度钒基超级电容器电极材料

Low energy density is the main technology bottleneck for development of supercapacitors, while enhancing working voltage and specific capacitance are two key solutions. Vanadium-based electrode materials, showing pretty high working voltage in range of 1.2 and 1.8 V, has the basic potential to enhance energy of supercapacitors; meanwhile, coating electroactive vanadium nitride onto the carbon surface involving rational porous structure derived from the self-assemble of metal ion/ionic block copolymer largely improves the utilization level of vanadium nitride. However, there is still a big gap between the real and theoretical specific capacitance of the vanadium-based materials, and we believe that the reason is the not-good-wettability of electrode materials in electrolyte. Based on this case, this project proposes that functional polymer chains should be introduced by electrochemical mediated surface-initiated atom transfer random polymerization onto the electrode materials surface. The constructed polymer brush would be keeping wriggling in electrolyte, and command the migration of ions during the charging/discharging processing. Thus, the mass transfer efficiency of electrolyte ions in the electrolyte side of interface of electrode and electrolyte would be highly improved, and we predict that the specific capacitance and energy density of supercapacitor would be highly improved.

超级电容器发展的技术瓶颈是能量密度低，而改善的主要途径是提高工作电压和比电容。工作电压可以达到1.2至1.8伏的钒基电极材料具有从根本上提升超级电容器能量密度的基本特质；同时采用过渡金属离子/离子嵌段共聚物一步炭化法巧妙地将活性物质氮化钒负载到具有合理孔道结构的碳表面上，大大地提高了活性物质的利用率。遗憾的是，钒基电极材料的实际比电容距其理论比电容还是有很大的差距。我们将原因归结为钒基电极材料在电解液中的浸润性不好造成的。据此，本项目提出采用先进的电化学诱导表面引发原子转移自由基聚合技术，在表面引入与电解液能够高度浸润的功能性聚合物链段刷；在电解液中，该聚合物刷处于一种高度“蠕动”的状态，这有利于电解液离子在充放电过程中随着电解液与电极材料的有效浸润而快速、有效的迁移，改善电解液离子在电极/溶液界面上溶液一侧扩散区域的传质效率，从而制备高比容量和高能量密度的钒基超级电容器。

超级电容器发展的技术瓶颈是能量密度低，而改善的主要途径是提高工作电压和比电容；氮化钒作为一种负极材料具有1.2至1.8伏的工作电压，比电容却比较低。本项目通过在氮化钒表面/电解液界面处构筑亲电解液性聚合物分子刷，提高电极材料的比容量和能量密度。主要研究内容是氮化钒电极材料的制备及表面引发聚合、聚合物链段对电化学性能的影响、电解液离子在聚合物刷存在下的传质过程和氮化钒电极材料的优化制备及高能量密度超级电容器的组装。本项目的主要科学贡献是创新性的提出了氮化钒的储能机理以及探明了聚合物刷对其电化学储能性能的影响规律，实现了高容量氮化钒负极材料的优化制备（比电容高于380F/g）的总研究目标，并为将来氮化钒电极材料在超级电容器、电池负极等储能领域的广泛引用提供参考。

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