Bulk degradations of layered lithium transition metal oxide are drawing great attention but still lacking in-depth understanding.Dislocation is one of the major bulk defects in both pristine and cycled particles.It is closely related to cracking and phase transition.Thus,it plays an important role in affecting the electrochemical performance of layered-structure cathodes.Herein,by virtue of transmission electron microscopy,we examined three types of dislocations in layered cathodes.We found that the core structure of(003)edge dislocation was highly disordered after high voltage cycling.Considering the high density of dislocations,such dislocation-associated disordered phases were supposed to block Li ion diffusion pathways and consequently plunged energy storage capability.While the screw dislocations and the(102)edge dislocations had stable dislocation cores.Our work demonstrated that intrinsic dislocation defects played an important role in affecting cycling stability.Engineering of intrinsic defects,such as point defects,line defects,and planar defects,could provide plenty of room to improve battery performance.
关键词
锂离子电池/三元层状氧化物正极/透射电子显微镜/位错/晶格
Key words
lithium ion battery/layered cathode/transmission electron microscopy/dislocation/lattice structure
维普
万方数据