氧化-超声波除钾对活性炭材料电化学性能的影响

以毛竹炭化料为原料,经KOH活化、盐酸溶液洗涤,制得活性炭样品AC1。采用H2O2氧化-超声波法对活性炭AC1进行深度除钾,考察了不同条件对活性炭中K+含量的影响,并通过N2吸附-脱附等温线、循环伏安、恒流充放电和交流阻抗等方法对活性炭的孔结构及电化学性能进行了表征。结果表明:在H2O2质量分数为0.6%,超声波处理温度为60℃,超声波处理时间为8 h条件下,处理后的活性炭AC2的K+仅为52 mg/kg,比表面积达3 156 m2/g,总孔容积1.625 cm3/g,中孔率79.8%,平均孔径2.208 nm。活性炭AC2用作电极材料时比电容达297 F/g,相比AC1提高28%,经3 000次循环后,电容保持率为95%,比AC1提高6个百分点,具有优异的电化学性能。

Influence of Removal of Potassium from Activated Carbon by Using Oxidation-ultrasonic Method on Its Electrochemical Properties

The activated carbon(AC1)was prepared from moso bamboo carbide by KOH activation and hydrochloric acid solution washing. Then AC1 sample was further treated with H2O2 oxidation-ultrasonic method to deeply remove the K+. The effects of different experimental conditions on the removal of K+ content of ACs were studied. The pore structures of the AC samples were characterized by N2 adsorption-desorption isotherm, and electrochemical properties were characterized by cyclic voltammetry, constant current charge-discharge and electrochemical impedance spectroscopy. The results showed that high quality activated carbon(AC2)could be obtained under the conditions of mass fraction of H2O2 solution 0. 6%, ultrasonic reaction temperature 60 ℃ and ultrasonic reaction time 8 h. And the K+ content was 52 mg/kg, specific surface area was 3 156 m2/g, pore volume was 1. 625 cm3/g, ratio of mesopore was 79. 8% and average pore size was 2. 208 nm. For the electrochemical properties, it displayed a specific capacitance of 297 F/g and a high capacitance retention of 95% after 3 000 cycles. They increased by 28%and 6 percentage points, respectively, compared with AC1 sample. They indicated excellent capacitive behavior.