Details

Autor(en) / Beteiligte

• Wu, Feng
• Liu, Na
• Chen, Lai
• Su, Yuefeng
• Tan, Guoqiang
• Bao, Liying
• Zhang, Qiyu
• Lu, Yun
• Wang, Jing
• Chen, Shi
• Tan, Jing

Titel

Improving the reversibility of the H2-H3 phase transitions for layered Ni-rich oxide cathode towards retarded structural transition and enhanced cycle stability

Ist Teil von

• Nano energy, 2019-05, Vol.59 (C), p.50-57

Ort / Verlag

United States: Elsevier Ltd

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Although the layered Ni-rich LiNixCoyMn1-x-yO2 (0.7 < x < 1, 0 < y < 0.3) cathode materials are expected to deliver high capacity, their moderate cycle lifetime and thermal stability still hinder practical applications. There's often a tradeoff between high capacity and structure stability since more Li+ ions delithiated during charging will leave the structure of the layered Ni-rich materials more vulnerable. Herein, we propose that improving the reversibility of H2-H3 phase transition for Ni-rich materials is effective to tackle this challenge. It has been confirmed that the generation of microcracks and structural transformations have been suppressed since the H2-H3 phase transition becomes reversible, while which shows little effect on capacity delivery. Consequently, using Ni-rich LiNi0.9Co0.1O2 as the cathode material, the 100th capacity retention cycling at 38 mA g−1 has been improved remarkably from 69.7% to 97.9% by adopting this strategy. Hence, it should be a novel solution to realize both high capacity and stable cyclability for the Ni-rich cathodes. This work proposed a new way, i.e. pre-fabricating the surface of Ni-rich cathode with a cation-mixing layer through surface Ti-doping, to improve the reversibility of H2-H3 phase transition during the long cycles. The repeated formation of H3 phase in every charge-discharge process can afford the high capacity delivery, while the lossless H3 phase guarantees superior cycling stability. We consider this as a new idea to realize both high capacity and stability for Ni-rich cathodes. [Display omitted] •A surface nanoscaled cation-mixing layer is fabricated for Ni-rich material through appropriate surficial Ti4+ substitution.•This preformed cation-mixing layer can improve the reversibility of H2-H3 phase transition.•Reversible H2-H3 phase transition contributes to realize both high capacity and stable cyclability for the Ni-rich cathodes.