Preparation And Performance Of Activated Carbons Based On Bamboo Shoot Shell For Supercapacitors

Activated carbon materials with unique characteristics, such as good chemical and thermal stability, high specific surface area, easy availability and relatively low cost, are especially preferred for the EDLCs. However, all kinds of activated carbon materials are mainly produced from fossil-fuel(petroleum and coal)-based and wood-based precursors, and the associated environmental problems limit its further development and application. So, the activated carbons derived from waste biomass precursors have become more attractive recently. In this thesis, bamboo shoot shell(BSS),an inexpensive and abundant resource are firstly used to fabricate activated carbon electrodes for the EDLCs. Furthermore, the synthesis route of activated carbon materials by the direct carbonization of BSS and subsequent activation treatment at high temperature is put forward. In addition, the effects of activation conditions on the supercapacitive performance of activated carbons derived from bamboo shoot shell have also been investigated. The main research work is as follows:(1) The novel bamboo shoot shell-derived activated carbon has been obtained by carbonization at 600 °C for 3 h in Ar atmosphere and following activated by KOH. With increasing the amount of activation agent, the specific surface area and electrochemical performances of the as-prepared carbon samples are also enhanced. Based on the experimental results, the BSSDAC-5 synthesized at 5:1 weight ratio of KOH to bamboo shoot shell-derived carbon owns a high specific surface area of 3408 m2 g-1 with the pore size of 2.52 nm. In addition, BSSDAC-5 shows a high specific capacitance of 308 F g-1 at 1 A g-1, and it also exhibits excellent capacity retention of 97.4% after 10000 cycles.(2) The porous carbons derived from naturally abundant bamboo shoot shell for the application of supercapacitor are further activated by chemical activation with Zn Cl2, H3PO4, K2CO3 and KOH. The influences of activation condition on the pore structure and physicochemical properties of the as-prepared porous carbon samples are investigated. Based on the experimental results, Zn Cl2, H3PO4, K2CO3 and KOH works more effectively as activating reagents at 600 °C, 700 °C, 900 °C and 900 °C, respectively. Accordingly, the AC-Zn Cl2-600, AC-H3PO4-700, AC-K2CO3-900 and AC-KOH-900 show a specific surface area of 1697 m2 g-1, 1260 m2 g-1, 1800 m2 g-1 and 2109 m2 g-1, respectively. In additon, the specific capacitances of AC-Zn Cl2-600, AC-H3PO4-700, AC-K2CO3-900 and AC-KOH-900 are up to 251, 208, 269 and 286 F g-1 at 1 A g-1, respectively.(3) The optimal bamboo shoot shell derived activated carbon materials(BSSDAC-5 and AC-KOH-900) are used as the electrode material for supercapacitors. The electrochemical performances of BSSDAC-5 and AC-KOH-900 supercapacitors with 1 M Li PF6/(EC+DMC) are investigated. The results show that BSSDAC-5 and AC-KOH-900 supercapacitors exhibit specific capacitance of 156 F g-1 and 105 F g-1 at 5 m V s-1, respectively. In addition, BSSDAC-5 and AC-KOH-900 supercapacitors obtain a high energy desity of 33.2 Wh kg-1 and 47.5 Wh kg-1, respectively. Especially, they also exhibit excellent capacity retention of 90% after 10000 cycles at 1 A g-1.