Enhancing low-temperature electrochemical kinetics and high-temperature cycling stability by decreasing ionic packing factor  

作　　者：Changpeng Lv Chunfu Lin Xiu Song Zhao 

机构地区：[1]Institute of Materials for Energy and Environment,College of Materials Science and Engineering,Qingdao University,Qingdao 266071,China [2]Anhui Provincial Engineering Laboratory of Silicon-based Materials,Engineering Technology Research Center of Silicon-based Materials Anhui,School of Material and Chemical Engineering,Bengbu University,Bengbu,233030,China

出　　处：《eScience》2023年第6期69-79,共11页电化学与能源科学（英文）

基　　金：supported by the National Natural Science Foundation of China (51762014);Key Research Project of Natural Science in Universities of Anhui Province (KJ2020A0749);Excellent Young Talents Foundation in Universities of Anhui Province (gxyq2021223).

摘　　要：Present-day Liþstorage materials generally suffer from sluggish low-temperature electrochemical kinetics and poor high-temperature cycling stability.Herein,based on a Ca2þsubstituted Mg_(2)Nb_(34)O_(87) anode material,we demonstrate that decreasing the ionic packing factor is a two-fold strategy to enhance the low-temperature electrochemical kinetics and high-temperature cyclic stability.The resulting Mg_(1.5)Ca_(0.5)Nb_(34)O_(87) shows the smallest ionic packing factor among Wadsley–Roth niobate materials.Compared with Mg_(2)Nb_(34)O_(87),Mg1.5Ca0.5Nb_(34)O_(87) delivers a 1.6 times faster Liþdiffusivity at-20℃,leading to 56%larger reversible capacity and 1.5 times higher rate capability.Furthermore,Mg_(1.5)Ca_(0.5)Nb_(34)O_(87) exhibits an 11%smaller maximum unit-cell volume expansion upon lithiation at 60℃,resulting in better cyclic stability;at 10C after 500 cycles,it has a 7.1%higher capacity retention,and its reversible capacity at 10C is 57%larger.Therefore,Mg_(1.5)Ca_(0.5)Nb_(34)O_(87) is an allclimate anode material capable of working at harsh temperatures,even when its particle sizes are in the order of micrometers.

关 键 词：Ionic packing factor Low-temperature electrochemical kinetics High-temperature cycling stability Wadsley–Roth niobate SUBSTITUTION In situ characterization 

分 类 号：O646[理学—物理化学]