Structural Regulation Of Carbon Tile/Carbon Nanotube Based Composite Electrode For Supercapacitors

Biomass activated carbon has the advantages of large specific surface area,lost cost and wide source,and is an attractive electrode material for carbon-based supercapacitors.However,the electrode constructed by activated carbon usually has long and tortuous ion channels,which leads to a significant decrease in porosity utilization and greatly limits its energy storage performance.In order to solve this problem,in this paper,biomass carbon tile（CT）with unique structure and highly conductive single-wall carbon nanotubes（SWNT）were used as electrode materials,the structure of electrode was adjusted by layer-by-layer assembled method and 3D printing technology.SWNT/CT carbon paper electrode and CT/SWNT/Ni Co₂O₄ aerogel electrode with good conductivity and rapid ion transfer were constructed.And its structure and electrochemical performance were studied,the specific results are as follows:（1）Using kapok as raw material,porous thin-wall quasi 2D CT was prepared by pre-stabilization、carbonization activation and ultrasonic crushing,CT has curved structure with wall thickness of about 700 nm and pore distribution of about 1 nm.SSAs and pore volume are up to 1639 m² g^-1and 0.8308 cm³ g^-1,respectively.In addition,CT is rich in N,O and P heteroatoms.The composition and unique structure of CT provide sufficient charge accumulation surface area for the CT-based electrode,which is conducive to infiltration of electrolyte and rapid ion transport.（2）A novel,free-standing,flexible and multiparous carbon paper electrode was constructed by layer-by-layer assembled with biomass CT as the main component and highly conductive SWNTs as the auxiliary component.The bulk density,SSAs and electrical conductivity reached 0.8 g cm^-3,1098 m² g^-1 and 198 S cm^-1,respectively.The 3D conductive network structure formed by SWNTs bridge inside electrode promotes rapid charge transfer,and the rich nano-pore structure and layer spacing formed by CT provide rich channels for infiltration and transmission of electrolyte ions.The assembled symmetrical supercapacitor has high rate performance.The capacitance retention of aqueous and organic supercapacitors is 60%at scan rate of 3000 and 1000m V s^-1,respectively.In addition,the device shows excellent cycle stability,with the capacitance retention of 97%and 83.4%for aqueous and organic supercapacitors after charging and discharging for 10000 and 20000 times,respectively.（3）An interconnected multiporous CT/SWNT/Ni Co₂O₄ aerogel electrode was constructed by extrusion forming 3D printing technology and polymer-assisted hydrothermal method.The highly conductive porous electrode not only realized efficient and uniform loading of pseudocapacitive material Ni Co₂O₄,but also provided abundant channels for rapid ion/electron transport.The electrochemical test results showed that the pseudocapacitive electrode with Ni Co₂O₄ loading of 31 mg cm^-2 had higher energy storage performance,and the surface capacitance reached 1.32 F cm^-2.CT/SWNT/Ni Co₂O₄ and CT/SWNT aerogel were used as positive and negative poles respectively to construct asymmetric supercapacitors.The areal capacitance and energy density reach 588 m F cm^-2 and 138μWh cm^-2,respectively.The device retains a remarkable 87.4%of its initial capacitance and high coulombic efficiency of nearly 100%after 5000 charge-discharge cycles,manifesting an excellent long-term cycling stability.In the device assembled by 3D printing thick electrodes,the charge and ion can maintain efficient and fast transmission,which can realize the construction of devices with high energy storage performance.There are 85 figures,3 tables and 100 references.