基于三维花状五氧化二铌及活性炭的锂离子混合电容器

锂离子混合电容器由于兼备锂离子电池和超级电容器的优势,即较高的能量密度和功率密度,而成为当前能量存储体系的研究热点。本工作合成了具有三维花状微纳结构的正交相五氧化二铌(T-Nb_2O_5),并将其与活性炭(AC)相匹配,设计出一种新型的T-Nb_2O_5/AC锂离子混合电容器。循环伏安和恒电流充放电的测试结果表明该锂离子混合电容器具有较好的电化学性能,如在碳酸酯类的有机电解液中,工作电压可达到3.0 V;在100 m A·g~(-1)的电流密度下,电容器的比能量和比功率密度可达到53.79 Wh·kg~(-1)和294 W·kg~(-1);在200 m A·g~(-1)的电流密度下,经过1000次充放电循环后,该电容器的比能量保持率为73%。由此可见,本工作开发的T-Nb_2O_5/AC锂离子混合电容器将在高功率的储能设备中有很好地应用前景。

Lithium Ion Hybrid Supercapacitor Based on Three-Dimensional Flower-Like Nb2O5 and Activated Carbon Electrode Materials

A lithium ion hybrid supercapacitor system with battery and supercapacitor characteristics has the potential to meet the increasing demand for an energy storage device with both high energy and power densities. In this work, orthorhombic Nb₂O₅ (T-Nb₂O₅) with three-dimensional (3D) flower-like structures was synthesized by a facile hydrothermal reaction and an annealing process. A lithium ion hybrid supercapacitor was constructed by using T-Nb₂O₅ as an anode and commercial activated carbon (AC) as a cathode. The electrochemical performance of these T-Nb₂O₅/AC hybrid capacitors was measured by cyclic voltammetry and galvanostatic charge/discharge tests. The results showed that the working voltage of the hybrid supercapacitor could reach 3.0 V in the organic carbonate electrolyte system. The as-assembled device showed impressive power density of 294 W·kg^-1 and energy density of 53.79 W·h·kg^-1 at a current density of 100 mA·g^-1 with a voltage range of 0.5-3.5 V. Moreover, it also showed excellent cycling stability with a retention of 73% after 1000 cycles at 200 mA·g^-1. These results demonstrate that this novel lithium ion hybrid supercapacitor based on T-Nb₂O₅ with 3D flower-like structures and AC is a promising candidate for high power density energy storage applications.