摘要
Rapid capacity decay and inferior kinetics are the vital issues of anodes in the conversion reaction for lithium-ion batteries.Vacancy engineering can efficiently modulate the intrinsic properties of transition-metal oxide(TMO)-based electrode materials,but the effect of oxygen vacancies on electrode performance remains unclear.Herein,abundant oxygen vacancies are in situ introduced into the lattice of different TMOs(e.g.,Co_(3)O_(4),Fe_(2)O_(3),and NiO)via a facile hydrothermal treatment combined with calcination.Taking Co_(3)O_(4)as a typical example,results prove that the oxygen vacancies in Co_(3)O_(4−x)effectively accelerate charge transfer at the interface and significantly increase electrical conductivity and pseudocapacitance contribution.The Li-ion diffusion coefficient of Co_(3)O_(4−x) is remarkably improved by two orders of magnitude compared with that of Co_(3)O_(4).Theoretical calculations reveal that Co_(3)O_(4−x)has a lower Li-insertion energy barrier and more density of states around the Fermi level than Co_(3)O_(4),which is favorable for ion and electron transport.Therefore,TMOs with rich vacancies exhibit superior cycling performance and enhanced rate capability over their counterparts.This strategy regulating the reaction kinetics would provide inspiration for designing other TMObased electrodes for energy applications.
转化反应过程中锂离子电池负极材料面临容量快速衰减和动力学缓慢的问题.氧空位缺陷可以有效调节过渡金属氧化物(TMO)基电极材料的内在特性,但是,氧空位对电极材料性能的影响机制尚不清楚.本研究通过简单的方法,将丰富的氧空位原位引入到不同TMO(例如Co_(3)O_(4)、Fe_(2)O_(3)和NiO)的晶格中.以Co_(3)O_(4)为例,Co_(3)O_(4−x)中的氧空位能够有效加快界面处的电荷转移,显著提高电导率和赝电容贡献.理论计算表明,氧空位的引入能够降低锂嵌入能垒,且增加费米能级附近的态密度,有利于离子和电子传输.因此,富含氧空位的TMO表现出更优异的循环稳定性和倍率性能.本研究可以为设计用于能源应用的其他TMO电极材料提供参考.
作者
Xunlu Wang
Jie Liu
Yifan Hu
Ruguang Ma
Jiacheng Wang
王寻路;刘婕;胡一帆;马汝广;王家成(State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 201899,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;School of Materials Science and Engineering,Suzhou University of Science and Technology,Suzhou 215011,China)
基金
supported by the National Natural Science Foundation of China(92163117 and 52072389)
the Program of Shanghai Academic Research Leader(20XD1424300)。
