Lotus-stalk Bi4Ge3O12 as binder-free anode for lithium and sodium ion batteries

Alloyed-type anode materials with high-energy density for lithium and sodium ion batteries attracted much attention of the researchers. However, substantial volume expansion of these materials in the devices during repeated electrochemical process leads to fast capacity fading and hinders their further practical application. Nanotechnology could act as a useful tool to effectively address the issue. Herein, lotus-stalk Bi4Ge3O12 nanosheets vertically grown on the nickel foam (denoted as Bi4Ge3O12 NSs@NF) were prepared via a straight-forward solvothermal method. Benefiting from their three dimensional (3D) conductive framework and two dimensional (2D) lotus-stalk Bi4Ge3O12 nanosheet structure, as anode materials of lithium-ion batteries (LIBs) and sodium-ion batteries (NIBS), the electrochemical performances of Bi4Ge3O12 NSs@NF were greatly enhanced as a result of mitigating the huge volume variations during cycles. The Bi4Ge3O12 NSs@NF electrodes delivered a high reversible capacity of 1033.1 mAh/g for the first cycle and exhibited 68.6% capacity retention of after 88 cycles at 0.10 A/g in the voltage window of 0.01 similar to 3.0 V versus Li/Li+. In the test of NIBs, the lotus-stalk Bi4Ge3O12 composite electrodes still stored Na+ as high as 3323 mAh/g at 0.10 A/g over 100 sodiation/desodiation repeating cycles. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.