Garakani Mohammad Akbari, Abouali Sara, Zhang Biao, Takagi Curtis Alton, Xu Zheng-Long, Huang Jian-qiu, Huang Jiaqiang, Kim Jang-Kyo
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
ACS Appl Mater Interfaces. 2014 Nov 12;6(21):18971-80. doi: 10.1021/am504851s. Epub 2014 Oct 28.
Nanocomposites consisting of ultrafine, cobalt carbonate nanoneedles and 3D porous graphene aerogel (CoCO3/GA) are in situ synthesized based on a one-step hydrothermal route followed by freeze-drying. A further heat treatment produces cobalt oxide nanoparticles embedded in the conductive GA matrix (Co(3)O(4)/GA). Both the composite anodes deliver excellent specific capacities depending on current density employed: the CoCO(3)/GA anode outperforms the Co(3)O(4)/GA anode at low current densities, and vice versa at current densities higher than 500 mA g(-1). Their electrochemical performances are considered among the best of similar composite anodes consisting of CoCO(3) or Co(3)O(4) active particles embedded in a graphene substrate. The stable multistep electrochemical reactions of the carbonate compound with a unique nanoneedle structure contribute to the excellent cyclic stability of the CoCO(3)/GA electrode, whereas the highly conductive networks along with low charge transfer resistance are responsible for the high rate performance of the Co(3)O(4)/GA electrode.
基于一步水热法随后进行冷冻干燥原位合成了由超细碳酸钴纳米针和三维多孔石墨烯气凝胶组成的纳米复合材料（CoCO₃/GA）。进一步的热处理产生嵌入导电GA基体中的氧化钴纳米颗粒（Co₃O₄/GA）。两种复合阳极根据所采用的电流密度均具有出色的比容量：CoCO₃/GA阳极在低电流密度下优于Co₃O₄/GA阳极，而在高于500 mA g⁻¹的电流密度下则相反。它们的电化学性能被认为是由嵌入石墨烯基体中的CoCO₃或Co₃O₄活性颗粒组成的类似复合阳极中最好的。具有独特纳米针结构的碳酸盐化合物的稳定多步电化学反应有助于CoCO₃/GA电极具有出色的循环稳定性，而高导电网络以及低电荷转移电阻则是Co₃O₄/GA电极高倍率性能的原因。
