Energy Storage Performance Of Activated Kiwi Fruit Peel Carbon And Its Composites

Due to the advantages of high power density and long cycle life,supercapacitors are widely used in the fields of emergency safety doors,high-power emergency power supply and portable electronic equipment,et al,but the low energy density makes it difficult to meet the actual demand.Electrode materials are the key to improve the electrochemical performance of supercapacitors.Kiwi fruit peel is a kind of biomass material,which is rich in pectin,vitamin C,calcium,potassium,magnesium and other trace elements with a natural macroporous structure.In this paper,the activated kiwi fruit peel carbon was prepared with kiwi fruit peel as the precursor,and was composite with two kinds of pseudocapacitor materials to explore the electrochemical properties of kiwi fruit peel carbon and its composite materials,and the influence of different mass ratios on the performance of capacitors.The main research content is divided into the following three parts:(1)With kiwi fruit peel as precursor,activated kiwi fruit peel carbon with high specific surface area was prepared by carbonization and pickling.The structure and composition of the activated kiwi fruit peel carbon were analyzed and the electrochemical properties of the all-solid-state capacitor assembled by the activated kiwi fruit peel carbon was explored.The electrochemical properties of the material were improved by electrochemical oxidation,and the electrochemical oxidized electrode material was composed of 1 V all-solid-state capacitor,the energy density of the all-solid-state capacitor can reach 6.4 Wh kg^-1(1 A g^-1),and the energy density retention rate is 85.4%after 10,000 cycles at 1 A g^-1.(2)The Ni-Mn layered double hydroxide nanosheets were prepared on the electrode by hydrothermal method using activated kiwi fruit peel carbon electrode as the substrate.The effects of synthesis time on the deposition amount and electrochemical performance were studied.The activatied kiwi fruit peel carbon/Ni-Mn layered double hydroxide metal anode and activatied kiwi fruit peel carbon cathode assembly into the 1.6 V asymmetric capacitor.The optimized asymmetric capacitor has excellent electrochemical performance,under the current density of 1 A g^-1,the energy density can be up to 24.2 Wh kg^-1 and the energy density retention rate after 1000 cycles was 85.4%(10 A g^-1).(3)?-Co(OH)₂ nanosheets were synthesized by hydrothermal method,and the effects of different mixing mass ratio with activated kiwi fruit peel carbon on the electrochemical properties of the composites were studied.The 1.6 V asymmetric capacitor was assembled by the activated kiwi fruit peel carbon/?-Co(OH)₂ anode and the activated kiwi fruit peel carbon cathode.The asymmetric capacitor has good cycle stability(at the high current density of 10 A g^-1,the energy density retention rate is still 90.1%after 2000 cycles).When the current density is 1 A g^-1,the energy density is 9 Wh kg^-1.