A New Germanium-Based Anode Material with High Stability for Lithium-Ion Batteries
Xinle Cao, Yongjie Cao, Haoyang Peng, Yuanjie Cao, Haifeng Zhu, Nan Wang, Xiaoli Dong, Congxiao Wang, Yao Liu, Jinsong Wu, Yongyao Xia
Abstract
The anode materials based on conversion or alloying reaction typically show a large specific capacity and suitable working potential in lithium-ion batteries (LIBs). However, the large volume change and relatively low ionic/electronic conductivity lead to poor reversibility and cycle life. In the present work, we report a new lithium–niobium germanate LiNbGeO5 material as the anode material for LIBs in which the in situ formed intermediate LiNbO3 with high ionic/electronic conductivity was introduced during the discharge/charge process. In situ X-ray diffraction and synchrotron-based X-ray absorption near edge spectroscopy proved that conversion and alloying mechanisms were combined. In situ transmission electron microscopy shows a volume change of 30% in the lithiation of carbon-coated LiNbGeO5 (LNGO@C). As a consequence, the LNGO@C anode exhibits a reversible discharge specific capacity of 785 mAh g–1 with a corresponding initial Coulombic efficiency of 76%, and great cycling stability without capacity loss after 5000 cycles at 10 A g–1 (∼75 C). Paired with a LiNi0.5Mn1.5O4 cathode, a full cell was assembled and exhibited a maximum energy density of 368 Wh kg–1 and a power density of 618.7 W kg–1 with an average output voltage of 3.65 V. The work develops a new reaction mechanism for conversion-type materials for LIBs.