Abstract Prospects of transition metal oxide (TMO) anodes in practical Li-ion batteries are limited despite their high capacity, owing to conversion reaction-driven inefficiencies and poor cycle life. Size confinement of TMOs and compositing them with carbon architectures is an established approach to realize high-performance electrodes. Here, we report cobalt oxide nanoparticles anchored on graphene (CoG) nanocomposite for Li-ion batteries; the anode exhibits a reversible capacity of 1270 mA h g−1 at 2 C rate and delivers 770 mA h g−1 even at a high rate of 50 C (44.5 Ag-1) of which >99% is retained at the end of 1000 cycles. Although many papers have reported exorbitant high capacity and rate performance for graphene–3d metal oxide composites, the nature of charge storage in these nanocomposites remains unidentified particularly in the voltage region of conversion reaction. By using cobalt oxide-anchored graphene as a model system, we reveal that the charge storage is a collective response from conversion/intercalation and pseudocapacitive processes. In addition, the CoG composite anode reported here provides excellent chemical stability and high durability as witnessed in terms of high capacity, impressive rate performance, and long cycle life. This study illustrates the benefits of nanoarchitecturing toward designing high-performance electrodes.

中文翻译：

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氧化钴锚定石墨烯纳米复合材料中电荷存储的起源

摘要尽管过渡金属氧化物 (TMO) 负极在实际锂离子电池中具有高容量，但由于转化反应驱动的效率低下和循环寿命差，其前景受到限制。TMO 的尺寸限制并将它们与碳结构复合是实现高性能电极的既定方法。在这里，我们报告了用于锂离子电池的固定在石墨烯 (CoG) 纳米复合材料上的氧化钴纳米颗粒；阳极在 2 C 倍率下表现出 1270 mA hg-1 的可逆容量，即使在 50 C (44.5 Ag-1) 的高倍率下也能提供 770 mA hg-1，其中在 1000 次循环结束时保留了 >99% . 尽管许多论文报道了石墨烯-3d 金属氧化物复合材料的超高容量和倍率性能，这些纳米复合材料中电荷存储的性质仍未确定，特别是在转化反应的电压区域。通过使用氧化钴锚定的石墨烯作为模型系统，我们发现电荷存储是转换/嵌入和赝电容过程的集体响应。此外，这里报道的 CoG 复合负极提供了优异的化学稳定性和高耐久性，正如在高容量、令人印象深刻的倍率性能和长循环寿命方面所见证的。这项研究说明了纳米结构对设计高性能电极的好处。此处报道的 CoG 复合阳极提供了优异的化学稳定性和高耐久性，正如在高容量、令人印象深刻的倍率性能和长循环寿命方面所见证的。这项研究说明了纳米结构对设计高性能电极的好处。此处报道的 CoG 复合阳极提供了优异的化学稳定性和高耐久性，正如在高容量、令人印象深刻的倍率性能和长循环寿命方面所见证的。这项研究说明了纳米结构对设计高性能电极的好处。