Jin Shuaixing, Yang Gongzheng, Song Huawei, Cui Hao, Wang Chengxin
The Key Laboratory of Low-Carbon Chemistry & Energy Conservation of Guangdong Province, ‡State Key Laboratory of Optoelectronic Materials and Technologies, and §School of Physics Science and Engineering, Sun Yat-sen (Zhongshan) University , Guangzhou 510275, People's Republic of China.
ACS Appl Mater Interfaces. 2015 Nov 11;7(44):24932-43. doi: 10.1021/acsami.5b08446. Epub 2015 Oct 27.
Two-dimensional (2D) nanostructures are a desirable configuration for lithium ion battery (LIB) electrodes due to their large open surface and short pathway for lithium ions. Therefore, exploring new anode materials with 2D structure could be a promising direction to develop high-performance LIBs. Herein, we synthesized a new type of 2D Ge-based double metal oxides for lithium storage. Ultrathin hexagonal Co2GeO4 nanosheets with nanochannels are prepared by a simple hydrothermal method. When used as LIB anode, the sample delivers excellent cyclability and rate capability. A highly stable capacity of 1026 mAhg(-1) was recorded after 150 cycles. Detailed morphology and phase evolutions were detected by TEM and EELS measurements. It is found that Co2GeO4 decomposed into Ge NPs which are evenly dispersed in amorphous Co/Li2O matrix during the cycling process. Interestingly, the in situ formed Co matrix could serve as a conductive network for electrochemical process of Ge. Moreover, aggregations of Ge NPs could be restricted by the ultrathin configuration and Co/Li2O skeleton, leading to unique structure stability. Hence, the large surface areas, ultrathin thickness, and atomically metal matrix finally bring the superior electrochemical performance.
二维（2D）纳米结构因其具有大的开放表面和锂离子的短传输路径，是锂离子电池（LIB）电极理想的结构形态。因此，探索具有二维结构的新型负极材料可能是开发高性能锂离子电池的一个有前景的方向。在此，我们合成了一种新型的用于锂存储的二维锗基金属双氧化物。通过简单的水热法制备了具有纳米通道的超薄六方Co2GeO4纳米片。当用作锂离子电池负极时，该样品表现出优异的循环性能和倍率性能。在150次循环后记录到1026 mAhg(-1)的高稳定容量。通过透射电子显微镜（TEM）和电子能量损失谱（EELS）测量检测了详细的形貌和相演变。发现在循环过程中，Co2GeO4分解为均匀分散在非晶Co/Li2O基体中的Ge纳米颗粒。有趣的是，原位形成的Co基体可以作为Ge电化学过程的导电网络。此外，Ge纳米颗粒的团聚可以受到超薄结构和Co/Li2O骨架的限制，从而导致独特的结构稳定性。因此，大的表面积、超薄的厚度和原子级的金属基体最终带来了优异的电化学性能。
