Co@Co₃O₄@Nitrogen doped carbon (Co@Co₃O₄@NDC) composite is synthesized by high temperature carbonization of ionic liquids followed by low temperature thermal oxidation. In the process of high temperature carbonization, cobalt ions are reduced to metallic cobalt, producing Co@Nitrogen doped carbon (Co@NDC). Co@Co₃O₄@NDC composite is obtained after low temperature oxidation, in which a part of the metallic cobalt is oxidized to Co₃O₄. The structural characterizations indicate that the composite is composed of three crystalline phases (carbon, Co and Co₃O₄). The results of transmission electron microscopy study show that the carbon materials not only coat the Co@Co₃O₄ nanoparticles, but also form carbon network that connects the Co@Co₃O₄ nanoparticles. This conductive carbon network is beneficial to improve the electrochemical performance of the composite. The electrochemical test results show that the Co@Co₃O₄@NDC composite exhibits excellent electrochemical performance, delivering the discharge capacities of 790 and 304 mAh·g⁻¹ after 1500 cycles at 5 C and 10 C. This excellent electrochemical performance is due to synergistic effects of Co₃O₄, cobalt nanoparticles embedded in carbon which has high conductivity, and nitrogen functional groups.

中文翻译：

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以离子液体为高性能锂离子电池的负极材料轻松制备Co @ Co3O4 @氮掺杂碳复合材料

Co @ Co ₃ O ₄氮掺杂碳（Co @ Co ₃ O ₄ NDC）复合材料是通过离子液体的高温碳化，然后进行低温热氧化而合成的。在高温碳化过程中，钴离子被还原成金属钴，从而产生了掺Co @ N的碳（Co @ NDC）。低温氧化后得到Co @ Co ₃ O ₄ @NDC复合材料，其中一部分金属钴被氧化成Co ₃ O ₄。结构表征表明该复合材料由三个晶相组成（碳，钴和钴₃ O ₄）。透射电子显微镜研究的结果表明，碳材料不仅覆盖了Co @ Co ₃ O ₄纳米颗粒，而且形成了连接Co @ Co ₃ O ₄纳米颗粒的碳网络。该导电碳网络有利于提高复合材料的电化学性能。电化学测试结果表明，Co @ Co ₃ O ₄ @NDC复合材料表现出优异的电化学性能，在5 C和10 C下经过1500次循环后的放电容量为790和304 mAh·g ^-1。对Co ₃ O _4的协同作用，嵌入碳中的钴纳米颗粒（具有高电导率）和氮官能团。