Pratheeksha Parakandy Muzhikara, Mohan Erabhoina Hari, Sarada Bulusu Venkata, Ramakrishna Mantripragada, Hembram Kalyan, Srinivas Pulakhandam Veera Venkata, Daniel Paul Joseph, Rao Tata Narasinga, Anandan Srinivasan
Centre for Nano Materials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad-500 005, India.
Centre for Solar Energy Materials, International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad-500 005, India.
Phys Chem Chem Phys. 2016 Dec 21;19(1):175-188. doi: 10.1039/c6cp06923a.
In the present study, LiFePO (LFP) has been synthesized using a flame spray pyrolysis unit followed by carbon coating on LFP using a novel strategy of dehydration assisted polymerization process (DAP) in order to improve its electronic conductivity. Characterization studies revealed the presence of a pure LFP structure and the formation of a thin, uniform and graphitic carbon layer with a thickness of 6-8 nm on the surface of the LFP. A carbon coated LFP with 3 wt% of carbon, using a DAP process, delivered a specific capacity of 167 mA h g at a 0.1C rate, whereas LFP carbon coated by a carbothermal process (CLFP-C) delivered a capacity of 145 mA h g at 0.1C. Further carbon coated LFP by the DAP exhibited a good rate capability and cyclic stability. The enhanced electrochemical performance of C-LFP by DAP is attributed to the presence of a uniform, thin and ordered graphitic carbon layer with a core-shell structure, which greatly increased the electronic conductivity of LFP and thereby showed an improved electro-chemical performance. Interestingly, the developed carbon coating process has been extended to synthesize a bulk quantity (0.5 kg) of carbon coated LFP under optimized experimental conditions as a part of up-scaling and the resulting material electro-chemical performance has been evaluated and compared with commercial electrode materials. Bulk C-LFP showed a capacity of 131 mA h g and 87 mA h g at a rate of 1C and at 10C, respectively, illustrating that the developed DAP process greatly improved the electrochemical performance of LFP in terms of rate capability and cyclic stability, not only during the lab scale synthesis but also during the large scale synthesis. Benchmark studies concluded that the electro-chemical performance of C-LFP by DAP is comparable with that of TODA LFP and better than that of UNTPL LFP. The DAP process developed in the present study can be extended to other electrode materials as well.
在本研究中，采用火焰喷雾热解装置合成了磷酸铁锂（LFP），随后通过脱水辅助聚合工艺（DAP）这一新颖策略对LFP进行碳包覆，以提高其电子导电性。表征研究表明存在纯LFP结构，且在LFP表面形成了厚度为6 - 8 nm的薄、均匀且呈石墨状的碳层。采用DAP工艺制备的含3 wt%碳的碳包覆LFP在0.1C倍率下的比容量为167 mA h g，而通过碳热法包覆碳的LFP（CLFP - C）在0.1C时的容量为145 mA h g。通过DAP进一步包覆碳的LFP表现出良好的倍率性能和循环稳定性。DAP法制备的C - LFP电化学性能增强归因于存在具有核壳结构的均匀、薄且有序的石墨碳层，这极大地提高了LFP的电子导电性，从而展现出改善的电化学性能。有趣的是，已将所开发的碳包覆工艺扩展到在优化实验条件下合成批量为0.5 kg的碳包覆LFP，作为扩大规模的一部分，并对所得材料的电化学性能进行了评估，并与商业电极材料进行了比较。批量C - LFP在1C和10C倍率下的容量分别为131 mA h g和87 mA h g，这表明所开发的DAP工艺不仅在实验室规模合成期间，而且在大规模合成期间，在倍率性能和循环稳定性方面都极大地改善了LFP的电化学性能。基准研究得出结论，DAP法制备的C - LFP的电化学性能与TODA LFP相当，且优于UNTPL LFP。本研究中开发的DAP工艺也可扩展到其他电极材料。
