School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 150001, Harbin, China.
Nanoscale. 2017 Jun 22;9(24):8481-8488. doi: 10.1039/c7nr00264e.
With the growing demand for portable and wearable electronic devices, it is imperative to develop high performance Li-ion batteries with long life times. Germanium-based materials have recently demonstrated excellent lithium-ion storage ability and are being considered as the most promising candidates for the anodes of lithium-ion batteries. Nevertheless, the practical implementation of Ge-based materials to Li-ion batteries is greatly hampered by the poor cycling ability that resulted from the huge volume variation during lithiation/delithiation processes. Herein, we develop a simple and efficient method for the preparation of Ge nanowires without catalyst nanoparticles and templates, using ionic liquid electrodeposition with subsequent annealing treatment. The Ge nanowire anode shows improved electrochemical performance compared with the Ge dense film anode. A capacity of ∼1200 mA h g after 200 cycles at 0.1 C is obtained, with an initial coulombic efficiency of 81.3%. In addition, the Ge nanowire anode demonstrates superior rate capability with excellent capacity retention and stability (producing highly stable discharge capacities of about 620 mA h g at 5 C). The improved electrochemical performance is the result of the enhanced electron migration and electron transport paths of the nanowires, and sufficient elasticity to buffer the volume expansion. This approach encompasses a low energy processing method where all the material is electrochemically active and binder free. The improved cycling stability and rate performance characteristics make these anodes highly attractive for the most demanding lithium-ion applications.
随着对便携式和可穿戴电子设备需求的不断增长，开发具有长寿命的高性能锂离子电池势在必行。基于锗的材料最近表现出了优异的锂离子存储能力，被认为是锂离子电池阳极最有前途的候选材料之一。然而，基于锗的材料在实际应用于锂离子电池时，由于在锂化/脱锂过程中体积变化巨大，导致其循环能力较差，从而受到极大的阻碍。在此，我们开发了一种无需催化剂纳米颗粒和模板的简单高效制备方法，采用离子液体电沉积，随后进行退火处理。与锗致密薄膜阳极相比，锗纳米线阳极显示出了改进的电化学性能。在 0.1 C 的电流密度下，经过 200 次循环后，其容量约为 1200 mA h g，初始库仑效率为 81.3%。此外，锗纳米线阳极还具有优异的倍率性能，具有出色的容量保持率和稳定性（在 5 C 的电流密度下，可产生高达约 620 mA h g 的稳定放电容量）。电化学性能的提高是由于纳米线增强了电子迁移和电子传输路径，以及足够的弹性来缓冲体积膨胀。这种方法采用了低能耗的处理方法，其中所有的材料都是电化学活性的，并且无需使用粘结剂。改进的循环稳定性和倍率性能特点使得这些阳极在最苛刻的锂离子应用中极具吸引力。
