Boosting reaction kinetics and reversibility in Mott-Schottky VS/MoS heterojunctions for enhanced lithium storage  

基于VS2/MoS2肖特基异质结储锂反应动力学和可逆性增强机制的研究

作　　者：Yuru Dong Yu Liu Yanjie Hu Kun Ma Hao Jiang Chunzhong Li 董玉茹;刘宇;胡彦杰;马坤;江浩;李春忠(Key Laboratory for Ultrafine Materials of Ministry of Education,Shanghai Engineering Research Center of Hierarchical Nanomaterials,School of Materials Science and Engineering,East China University of Science and Technology,Shanghai 200237,China;School of Chemical Engineering and Technology,Sun Yat-sen University,Guangzhou 510275,China)

机构地区：[1]Key Laboratory for Ultrafine Materials of Ministry of Education,Shanghai Engineering Research Center of Hierarchical Nanomaterials,School of Materials Science and Engineering,East China University of Science and Technology,Shanghai 200237,China [2]School of Chemical Engineering and Technology,Sun Yat-sen University,Guangzhou 510275,China

出　　处：《Science Bulletin》2020年第17期1470-1478,M0004,共10页科学通报（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(51672082,21975074 and 91534202);the Basic Research Program of Shanghai(17JC1402300);the Shanghai Scientific and Technological Innovation Project(18JC1410500);the National Program for Support of Top-Notch Young Professionals;the Fundamental Research Funds for the Central Universities(222201718002).

摘　　要：Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries(LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS2/MoS2 hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS2 vertically grown on MoS2 surface. The density functional theory(DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS2 surface. Furthermore, the VS2 catalytically expedites the Li–S bond fracture and meantime the enriched Mo6+ enables the sulfur anchoring toward the oriented reaction with Li+to form Li2S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS2/MoS2 hybrids deliver a very large specific capacity of 1273 m Ah g^-1 at 0.1 A g^-1 with 61% retention even at 5 A g^-1. It can also stabilize 100 cycles at 0.5 A g^-1 and 500 cycles at 1 A g^-1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.异质结中的内建电场能够极大地加快电荷转移动力学,因此开发具有异质结构的电极材料是提高锂离子电池比电容量的有效策略.本工作利用VS2和MoS2形成能之间的匹配关系,实现了金属性的寡层VS2纳米片在MoS2表面的垂直生长.通过调节VS2含量可以控制复合物中MoS2金属(1T)和半导体(2H)比例.密度泛函理论计算结果表明,该异质结构能够实现能级的重新排布并加快反应动力学,锂离子在其界面处的吸附能是单组分MoS2的2倍以上.此外,少层VS2能够催化断裂Li–S键,同时丰富的Mo6+还可以促进硫与锂离子定向反应形成硫化锂,从而协同增强了电化学反应过程的可逆性.最终获得的VS2/MoS2复合物的储锂比电容量高1270 mAh g^-1,在5 A g^-1的大电流下,比电容量仍能保持初始值的61%,并且具有优异的循环稳定性.本工作为构筑异质界面工程化提升储锂反应动力学和可逆性提供了理论指导和借鉴.

关 键 词：HETEROSTRUCTURE VS2/MoS2 Interface effect High-energy density Li-ion batteries 

分 类 号：TM912[电气工程—电力电子与电力传动] TB383.1[一般工业技术—材料科学与工程]