摘要
基于第一性原理计算,探究了未掺杂、Co单掺杂、Co,P共掺杂MoS_(2)表面上多硫化物的吸附和转化,揭示了Co,P共掺杂对MoS_(2)材料吸附能力和催化能力的影响.研究结果表明,共掺杂使得MoS_(2)吸附能力增强,特别是对产物Li_2S的稳定吸附提供了多硫化物转化动力,进而增强了催化能力.Co,P共掺杂表面与长链、中链、短链多硫化物之间均存在Li—S和S—P双重成键,具备最大的吸附能力;另一方面,共掺杂表面对于产物Li_2S的显著稳定化作用降低了多硫化物转化过程中解离步骤的能量需求,增大了转化过程的能量释放,为多硫化物转化提供了驱动力.上述两方面因素共同增强了MoS2的催化活性,有效抑制了穿梭效应,提升了电池的电化学性能.
In lithium-sulfur batteries,metal compound catalytic materials enhance the electrochemical redox reaction kinetics,fundamentally prevent the shuttle effect of polysulfides,and improve the electrochemical performance.MoS_(2) material has received widespread attention due to the affinity for polysulfides and catalytic ability.However,the base surface that occupies most of the reaction interface exhibits weaker catalytic activity than the few edge sites.The Co,P co-doping strategy was used for the first time to modify MoS_(2) material as cathode material in lithium-sulfur battery.Compared with undoped and Co single-doped materials,it achieves excellent discharge capacity,rate performance and cycling stability.To explore the origin of Co,P co-doping MoS_(2) to improve the electrochemical performance of lithium-sulfur batteries,the first-principles research was carried out,clarifying the adsorption and conversion of polysulfides on the surface of undoped,Co single-doped,Co,P co-doped MoS_(2).The calculation results indicate that the adsorption energy shows the trend of undoped<Co single doped<Co,P co-doped MoS_(2).The Li—S and S—P double bonding between the co-doped surface and polysulfides make Co,P co-doped MoS_(2) have the greatest adsorption capacity.Additionally,the significant stabilizing effect for discharge product Li2S reduces the energy requirement of the dissociation step and increases the overall energy release during the conversion process,providing driving forces for the polysulfide conversion.These two factors jointly enhance the catalytic activity of MoS_(2),effectively inhibit the shuttle effect,and improve the electrochemical performance of the battery.It is hoped that the conclusion could promote the application of surface modified metal sulfide catalytic materials in lithium-sulfur batteries.
作者
陈铭苏
张会茹
张琪
刘家琴
吴玉程
CHEN Mingsu;ZHANG Huiru;ZHANG Qi;LIU Jiaqin;WU Yucheng(Anhui Province Key Lab of Aerospace Structural Parts Forming Technology and Equipment,Institute of Industry&Equipment Technology,Hefei University of Technology,Hefei 230009,China;School of Materials Science and Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第8期2540-2549,共10页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:U1810204,21702041,51972093,U1910210)
中央高校基本科研业务费专项资金(批准号:JZ2020HGTB0062,PA2020GDJQ0026,PA2019GDPK0052,PA2020GDSK0088)
高等学校学科创新引智计划项目(批准号:B18018)
安徽省重点研发计划项目(批准号:202004b11020024)
安徽省自然科学基金(批准号:2008085ME129)资助。
关键词
二硫化钼
掺杂
催化
锂硫电池
第一性原理
MoS_(2)
Doping
Catalysis
Lithium-sulfur battery
First-principle
