J. Mater. Chem. A, 2015,3, 13933-13945

Mitigating capacity fade by constructing highly ordered mesoporous Al₂O₃/polyacene double-shelled architecture in Li-rich cathode materials

Ming Xu,^aZhaoyong Chen,Huali Zhu,^aXiaoyan Yan,^aLingjun Li^a and Qunfang Zhao^a

* Corresponding authors

^aSchool of Physics and Elctronic Science, Changsha University of Science and Technology, Changsha, China

E-mail:chenzhaoyongcioc@126.com

DOI:10.1039/C5TA03676C

Abstract

Lithium-rich layered oxides,xLi₂MnO₃·(1 −x)LiMO₂(M = Ni, Mn, Co), have been considered as one of the most promising cathode active materials for rechargeable lithium-ion batteries due to their high capacity over 250 mA h g⁻¹between 2.0 and 4.8 V. However, the commercialized application of these cathodes has so far been hindered by their severe capacity fading and transition metal dissolution during high voltage cycling (>4.5 Vvs.Li/Li⁺). To overcome this barrier, a double-shelled architecture consisting of an inner conductive polyacene layer and an outer mesoporous Al₂O₃layer is constructed. A polyacene layer with high electron conductivity is first coated on the surface of a 0.5Li₂MnO₃·0.5LiNi_0.5Co_0.2Mn_0.3O₂cathode material, followed by a hydrothermal method combined with an in-sol treatment to produce a highly ordered mesoporous Al₂O₃layer. Compared to previous studies, this double-shelled architecture has substantially improved the electrochemical performance of the 0.5Li₂MnO₃·0.5LiNi_0.5Co_0.2Mn_0.3O₂cathode material. Two striking characteristics are obtained for this double-shelled lithium-rich layered oxide cathode material: (1) the electrochemical capacity is greatly improved, reaching 280 mA h g⁻¹(2.0 V–4.8 V at 0.1 C) and (2) the transition from the layered phase to spinel is delayed, leading to a superior capacity retention of 98% after the 100^thcycle.