The pseudocapacitance mechanism of graphene/CoAl LDH and its derivatives:Are all the modifications beneficial?

• 来源期刊: 能源化学
• 年，卷（期）: 2021,（1）
• 页码范围: 218-227
• 页数: 10页
• 语种: 英文

摘要

Cobalt-Aluminum layered double hydroxide(CoAl LDH)is a hopeful electrode material due to the advan-tage of easy modifiability for preparing LDH-based derivatives.However,there is short of modification methods to prepare the Co-based derivatives from CoAl LDH and also short of an intuitive perspective to analyze the pseudocapacitance mechanism of CoAl LDH and its derivatives.Herein,Graphene/CoAl LDH and its derivatives including Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP were prepared by reasonably using alkali etching treatment,sulfofication and phosphorization.The specific capacitance of Graphene/CoAl LDH,Graphene/CoS,Graphene/CoS-1,Graphene/CoOOH,Graphene/CoP at 1 A g-1 are 260.7,371.3,440.8,61.4 and 122.2 F g-1,especially.The pseudocapacitance mechanism of Graphene/CoAl LDH and its derivatives was analyzed.Due to the positive effect of sulfofication on the electrical conductivity of GO and cobalt sulfide,the Graphene/CoS and Graphene/CoS-1 exhibit the op-timal electrochemical performance and superior rate capability.In addition,due to the repulsion effect between Graphene and OH-,the Graphene/CoAl LDH exhibits optimal cycling stability of 224.1％capaci-tance retention after 20000 cycles.Besides,the reason of terrible specific capacitance of Graphene/CoOOH is that the presence of H bond in interlayer of CoOOH inhibits the interaction between Co3+and OH-species.Hence,not all modifications will increase the specific capacitance of the electrode materials.Overall,this work provides us with a detailed analysis of the electrochemical mechanism and correla-tion of CoAl LDH and its derivatives from the perspective of crystal structure and composition.