纳米TiO_(2)/多孔碳复合材料的制备及其超级电容器性能的研究

Preparation of nano-TiO_(2) and porous carbon composites and their supercapacitor application

针对传统超级电容器中碳质材料受比表面积和孔径限制导致的比电容小,能量密度低(<10 Wh·kg^(-1))等问题,本工作利用瞬时纳米沉降技术(FNP)成功合成了SiO_(2)/MXene复合物,后利用聚四氟乙烯(PTFE)在800℃下进行热处理得到负载微量TiO_(2)颗粒的多孔碳材料(TiO_(2)/PC-800)。这种多孔结构可以提供更大有效比表面和化学反应活性位点,有利于缩短离子传输路径,加快离子传输。电化学测试结果表明TiO_(2)/PC-800具有较高的比电容,在0.5 A·g^(-1)的电流密度下比电容为215.5 F·g^(-1),同时还具有优异的循环稳定性,在10 A·g^(-1)的大电流密度下循环5000圈后比电容保持率为98.6%。组装的TiO_(2)/PC-800//TiO_(2)/PC-800对称型超级电容器在0.7 kW·kg^(-1)的功率密度下获得的能量密度高达50.8 Wh·kg^(-1)。因此,TiO_(2)/PC-800活性材料是一种极具应用潜力的超级电容器电极材料。

Carbonaceous materials suffer from low specific capacitance and low energy density(<10 Wh·kg^(-1))in conventional supercapacitors owing to limitations by specific surface area and pore size.This work first fabricates SiO_(2)/MXene complexes by the fast nano-precipitation technique(FNP).Then,SiO_(2)/MXene complexes are transformed into porous carbon materials loaded with trace TiO_(2) particles(TiO_(2)/PC-800)with the presence of polytetrafluoroethylene(PTFE)by a heat treatment process.This porous structure provides a larger effective specific surface and chemically reactive sites,shortening the ions transport pathways and thus accelerating the ions transports.The electrochemical test results show that TiO_(2)/PC-800 has high specific capacitance of 215.5 F·g^(-1) at a current density of 0.5 A·g^(-1) and excellent cycling stability with a specific capacitance retention rate of 98.6%after 5000 cycles at a current density of 10 A·g^(-1).The energy density of TiO_(2)/PC-800//TiO_(2)/PC-800 symmetrical supercapacitor is 50.8 Wh·kg^(-1) at a power density of 0.7 W·kg^(-1),confirming that as-prepared TiO_(2)/PC-800 is an extremely promising electrode material for supercapacitor applications.