Synthesis Of Cobalt Metal Oxide Nanomaterials And Their Performance In Supercapacitors

Supercapacotors,also named as electrochemical capacitors,are considered as the most promising next general energy storage system.Due to high power energy,long lifetime,fast charge/discharge rate,and environmentally friendly,supercapacotors have attracted much attention from researchers.The performance of supercapacotors depends on electrode materials,so the research of supercapacotors is focused on the synthesis of nanostructure electrode materials.Owing to their fast redox reactions and high specific capacitance,transition metal oxides?TMOs?are considered as promising electrode materials for pseudocapacitors.Thus,in this article,cobalt metal oxides?CMOs?are researched for the synthesized of nano-structure electrode materials,and the performance and storage mechanism are studied as supercapacitor.The main contents are as follow:?1?The study of high power density LiCoO₂ nano-flake as high performance supercapacitorLiCoO₂?LCO?usually can deliver high energy densities but low power density in Li-ion batteries?LIBs?.Owing to Faradaic redox reactions taking on its surfaces or inside crystals through ion intercalation/deintercalation from the surfaces,increasing specific area of LCO is a key factor to promote the rate capability.The LCO based electrode exhibits an excellent specific capacitance of 581.3 F·g-1 at 0.5 A·g-1,high power density of 2262 W×kg-1 at energy density of 41.0 Wh×kg-1,and good cycling stability?83.9% capacitance retention at 6 A·g-1 after 2000 cycles?in LiCl aqueous electrolyte.Faradaic redox behaviors have been analyzed,indicating an ideal diffusion-controlled process.Moreover,a full solid-state symmetric supercapacitor is assembled using LCO nanoflakes based electrodes,which presents good performance with light weight and flexibility.Impressively,three charged supercapacitors in series can light 100 green LED for 14 min.The LCO in nano-flake structure with high power density could be an excellent material for superior supercapacitors.?2?The study of Cu_0.3Co_0.7Co₂O₄ as high performance full solid-state supercapacitorHydrothermal method and annealing process are used for growing directly Cu_0.3Co_0.7Co₂O₄ nanorods on carbon cloth?CC?.FESEM images show Cu_0.3Co_0.7Co₂O₄ nanorods are consist of many nanowires,with high uniformity on carbon clothes.EDS pattern reveals uniform distribution of Cu,Co,O,indicating high purity.Based on Cu_0.3Co_0.7Co₂O₄/CC,the symmetrical solid-state supercapacitor is assembled.CV test reveals the full-solid state supercapacitor is charged and discharged at a pseudo-constant rate.And GCD test demonstrates high coulombic efficiency,high conductivity and low internal resistance for device.Furthermore,working voltage of device is researched.The solid-state supercapacitor is normal operation at 1.6 V,indicating stable charging and discharging rate,and good capacitive performance.