Oxygen vacancies and Li+ pre-embedding for magnesium storage in Anatase TiO2 toward magnesium/lithium hybrid batteries

Haofei Du, Xueyang Hou, Fan Cheng, Yifan Liu, Zhao Fang, Keyu Xie, Ling Zhang

科研成果: 期刊稿件文章同行评审

摘要

In the co-intercalation type of magnesium-lithium hybrid batteries (MLHBs) system, the insertion of Li+ enhances the electrochemical activity of the Chevrel phase cathode materials for Mg2+. However, the mechanism behind the synergistic diffusion mechanism of mixed multivalent ions still needs further research regarding other non Chevrel phase cathode materials. The present study is the first to reveal the diffusion mechanism of Li+/Mg2+ in oxygen vacancy anatase TiO2 (TiO2–x). Pristine TiO2 exhibits strong electrochemical inertness to Li+ and Mg2+, oxygen vacancies induce the preferential insertion of Li+ to form LiyTiO2–x structure. This in turn activates the electrochemical activity of TiO2 to Mg2+. Experimental results illustrate that the oxygen vacancies not only improve the intrinsic electronic conductivity of TiO2, but also weaken the electrostatic shielding effect between Mg2+ and lattice oxygen during the diffusion process. LiyTiO2–x compounds formed by Li+ preferentially intercalation can further reduce the diffusion energy barrier of Mg2+. The other hand, reduced graphene oxide (rGO) is used as the substrate to further improve the structural stability of TiO2–x. The prepared TiO2–x/rGO composite (denoted as NTR) as MLHBs cathode delivers outstanding lithium-magnesium co-storage performance (253.77 mAh g−1 at 0.1 A g−1; the capacity is 127.3 mAh g−1 at 0.5 A g−1 after 750 cycles). The present research emphasizes that the optimization of the charge environment during the diffusion of Mg2+ is an important factor in achieving the rapid diffusion of Mg2+. This modification strategy opens a new way for other transition metal oxides (TMOs) to be used as co-intercalated MLHBs cathode materials.

源语言英语
文章编号163769
期刊Chemical Engineering Journal
515
DOI
出版状态已出版 - 1 7月 2025

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