Co3O4/Co nanoparticles enclosed graphitic carbon as anode material for high performance Li-ion batteries
Co3O4/Co nanoparticles enclosed graphitic carbon as anode material for high performance Li-ion batteries
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DOI：
10.1016/j.cej.2017.03.146
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发表时间：
2017-08
影响因子：
15.1
通讯作者：
Zhiliang Yan;Hu Qiyang;Guochun Yan;Hangkong Li;K. Shih;Zhewei Yang;Xinhai Li;Zhixing Wang;
中科院分区：
文献类型：
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作者：
Zhiliang Yan;Hu Qiyang;Guochun Yan;Hangkong Li;K. Shih;Zhewei Yang;Xinhai Li;Zhixing Wang;
以羧甲基壳聚糖为原料，通过炭化和钴催化石墨化制备Co3O4、Co和石墨化碳的复合材料，然后进行低温热氧化。在高温下，Co（+2）被还原为金属Co，生成的Co作为热解碳石墨化的催化剂。低温氧化选择性地将Co氧化为co3o4，而碳保持未反应状态。结构分析表明，复合材料中存在三种晶相（石墨、金属Co、Co3O4），并伴有非晶态碳。形貌结果表明，碳中分布着大量Co元素周围的石墨颗粒。电化学测试结果表明，复合材料具有良好的电化学性能。它在低电流密度下提供843 mAh g - 1的可逆容量，在200 mA g - 1下60次循环后仍保持88.9%。即使在1a g−1下工作，它也能显示493 mAh g−1。性能的提高主要是由于Co3O4的高容量，石墨碳和金属钴的高导电性，多孔结构提供了足够的离子传输途径，减轻了循环过程中的应变。
The composite of Co3O4, Co and graphitized carbon is synthesized by carbonization and cobalt-catalyzed-graphitization of carboxymethyl chitosan, followed by low-temperature thermal oxidation. At the high temperature, the Co(+2) is reduced to metallic Co and the produced Co acts as a catalyst for the graphitization of the pyrolytic carbon. The low-temperature oxidation is conducted to selectively oxidize Co to Co3O4while the carbon remains unreacted. The structure analysis indicates that three crystal phases (graphite, metallic Co, Co3O4) accompanied with amorphous carbon are co-existed in the composite. Morphological results demonstrate that a lot of graphite grains around the Co element are distributed in the carbon. The electrochemical testing results indicate that the composite shows good electrochemical performance. It delivers a reversible capacity of 843 mAh g−1at low current density, and remains 88.9% after 60 cycles at 200 mA g−1. Even performed at 1 A g−1, it also exhibits 493 mAh g−1. The performance improvement is mainly due to the high capacity of Co3O4, high conductivity of graphitic carbon and metallic cobalt, the porous structure offering enough ion transport pathways and relieving the strain during cycling.