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(Li11/3Mn2/3)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 10mA/g)and stable cycling performance(84％over 60 cycles at 50mA/g).We predict that this strategy will be helpful to further improve the electrochemical performance of LRLOs.