Boosting Li-ion storage in Li2MnO3 by unequal-valent Ti4+-substitution and interlayer Li vacancies building

Lithium rich layered oxide (LRLO) has been considered as one of the promising cathodes for lithium-ion batteries (LIBs). The high voltage and large capacity of LRLO depend on Li2MnO3 phase. To ameliorate the electrochemical performance of Li2MnO3, also written as Li(Li1/3Mn2/3)O2, we propose a strategy to substitute Mn4+ and Li + in Mn/Li transition metal layer with Ti4 +, which can stabilize the structure of Li2MnO3 by inhibiting the excessive oxidation of O2- above 4.5 V. More significantly, the unequal-valent substitution brings about the emergence of interlayer Li vacancies, which can promote the Li-ion diffusion based on the enlarged interlayer and increase the capacity by activating the Mn3+/4+ redox. We designed Li0.7[Li1/3Mn2/3]0.7Ti0.3O2 with high interlayer Li vacancies, which presents a high capacity (290 mAh/g at 10 mA/g) and stable cycling performance (84% over 60 cycles at 50 mA/g). We predict that this strategy will be helpful to further improve the electrochemical performance of LRLOs.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

Substituting Mn and Li in the Mn/Li transition metal layer with Ti can stabilize the structure of Li2MnO3 and promote Li-ion diffusion. This strategy also increases the capacity and cycling performance of lithium-rich layered oxide cathodes for lithium-ion batteries.