稻壳基活性炭电极材料制备及其电化学性能研究

以稻壳为原料,氢氧化钠为活化剂,制备活性炭.进一步将该活性炭作为电极材料,以氢氧化钾溶液为电解液,组装超级电容器.采用X射线衍射(XRD)、氮气吸附脱附(BET)、扫描电镜(SEM)等手段,分析了不同活化温度对活性炭的比表面积及孔结构的影响,并利用恒流充放电、循环伏安等方法研究了电容器的电化学性能.结果表明:800 ℃活化下活性炭的比表面积最佳,为2760 m2/g,孔结构发达.此条件下,在6 mol/L的KOH电解液中,活性炭电容器比电容达267.2 F/g,等效内阻仅2.2 Ω,倍率性能好.经过5000次循环后,其电容保持率仍有83.7%,表明该稻壳基活性炭电极具有优异的充放电可逆性和循环稳定性.

Preparation and Electrochemical Performance of Rice Husk-based Activated Carbon Electrode

Activated carbon was prepared from rice husk, using sodium hydroxide as activator.Then activated carbon was selected as electrode to assemble supercapacitor with electrolyte of potassium hydroxide solution.X-ray diffraction (XRD),nitrogen adsorption-desorption (BET) and scanning electron microscopy (SEM) were used to study surface area and pore structure of carbon prepared at different temperatures.Meanwhile,the electrochemical performance of supercapacitor was investigated by constant current charge/discharge and cyclic voltammetry (CV).The results show that the specific surface area of carbon reaches the maximum value of 2760 m2/g at activation temperature of 800 ℃ with developed pore structure.Under the optimal activation condition, the specific capacitance of activated carbon recorded as the maximum value of 267.2 F/g in 6 mol/L of KOH solution,and the equivalent resistance was only 2.2 Ω with the good rate performance.The capacitance retention ratio was still keeping a high level of 83.7% after 5000 cycles.It indicates that the rice husk-based activated carbon exhibits good charge-discharge reversibility and cycle stability.