Tian Ruiyuan, Liu Haiqiang, Jiang Yi, Chen Jiankun, Tan Xinghua, Liu Guangyao, Zhang Lina, Gu Xiaohua, Guo Yanjun, Wang Hanfu, Sun Lianfeng, Chu Weiguo
†National Center for Nanoscience and Technology of China, Beijing 100190, P. R. China.
§China University of Geosciences, Beijing 100083, P. R. China.
ACS Appl Mater Interfaces. 2015 Jun 3;7(21):11377-86. doi: 10.1021/acsami.5b01891. Epub 2015 May 21.
Application of LiFePO4 (LFP) to large current power supplies is greatly hindered by its poor electrical conductivity (10(-9) S cm(-1)) and sluggish Li+ transport. Carbon coating is considered to be necessary for improving its interparticle electronic conductivity and thus electrochemical performance. Here, we proposed a novel, green, low cost and controllable CVD approach using solid glucose as carbon source which can be extended to most cathode and anode materials in need of carbon coating. Hydrothermally synthesized LFP nanorods with optimized thickness of carbon coated by this recipe are shown to have superb high-rate performance, high energy, and power densities, as well as long high-rate cycle lifetime. For 200 C (18s) charge and discharge, the discharge capacity and voltage are 89.69 mAh g(-1) and 3.030 V, respectively, and the energy and power densities are 271.80 Wh kg(-1) and 54.36 kW kg(-1), respectively. The capacity retention of 93.0%, and the energy and power density retention of 93.6% after 500 cycles at 100 C were achieved. Compared to the conventional carbon coating through direct mixing with glucose (or other organic substances) followed by annealing (DMGA), the carbon phase coated using this CVD recipe is of higher quality and better uniformity. Undoubtedly, this approach enhances significantly the electrochemical performance of high power LFP and thus broadens greatly the prospect of its applications to large current power supplies such as electric and hybrid electric vehicles.
磷酸铁锂（LFP）应用于大电流电源时，因其电导率差（10⁻⁹ S cm⁻¹）和Li⁺传输迟缓而受到极大阻碍。碳涂层被认为是提高其颗粒间电子电导率从而改善电化学性能所必需的。在此，我们提出了一种新颖、绿色、低成本且可控的化学气相沉积（CVD）方法，使用固体葡萄糖作为碳源，该方法可扩展到大多数需要碳涂层的阴极和阳极材料。通过该方法水热合成的具有优化碳涂层厚度的LFP纳米棒显示出卓越的高倍率性能、高能量和功率密度，以及长的高倍率循环寿命。对于200 C（18秒）充放电，放电容量和电压分别为89.69 mAh g⁻¹和3.030 V，能量和功率密度分别为271.80 Wh kg⁻¹和54.36 kW kg⁻¹。在100 C下500次循环后，容量保持率为93.0%，能量和功率密度保持率为93.6%。与通过与葡萄糖（或其他有机物质）直接混合然后退火（DMGA）的传统碳涂层相比，使用该CVD方法涂覆的碳相质量更高且均匀性更好。毫无疑问，这种方法显著提高了高功率LFP的电化学性能，从而极大地拓宽了其应用于电动和混合动力电动汽车等大电流电源的前景。
