Qiu Ce, Liu Jia, Liu Hanghui, Zhu Xiaohui, Xue Liang, Li Shuang, Ni Mingzhu, Zhao Yang, Wang Tong, Savilov Serguei V, Aldoshin Sergey M, Xia Hui
School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094, China.
Department of Chemistry, M. V. Lomonosov Moscow State University, Moscow, 119991, Russia.
Small Methods. 2022 Dec;6(12):e2201142. doi: 10.1002/smtd.202201142. Epub 2022 Nov 4.
Although birnessite-type manganese dioxide (δ-MnO ) with a large interlayer spacing (≈7 Å) is a promising cathode candidate for aqueous Zn/MnO batteries, the poor structural stability associated with Zn intercalation/deintercalation limits its further practical application. Herein, δ-MnO ultrathin nanosheets are coupled with reduced graphene oxide (rGO) via van der Waals (vdW) self-assembly in a vacuum freeze-drying process. It is interesting to find that the presence of vdW interaction between δ-MnO and rGO can effectively suppress the layered-to-spinel phase transition in δ-MnO during cycling. As a result, the coupled δ-MnO /rGO hybrid cathode with a sandwich-like heterostructure exhibits remarkable cycle performance with 80.1% capacity retained after 3000 cycles at 2.0 A g . The first principle calculations demonstrate that the strong interfacial interaction between δ-MnO and rGO results in improved electron transfer and strengthened layered structure for δ-MnO . This work establishes a viable strategy to mitigate the adverse layered-to-spinel phase transition in layered manganese oxide in aqueous energy storage systems.
尽管具有较大层间距（约7 Å）的水钠锰矿型二氧化锰（δ-MnO₂）是水系锌/二氧化锰电池中一种很有前景的阴极候选材料，但与锌嵌入/脱嵌相关的结构稳定性较差限制了其进一步的实际应用。在此，通过真空冷冻干燥过程中的范德华（vdW）自组装，将δ-MnO₂超薄纳米片与还原氧化石墨烯（rGO）耦合。有趣的是，发现δ-MnO₂与rGO之间存在的vdW相互作用能够有效抑制循环过程中δ-MnO₂的层状到尖晶石相转变。结果，具有三明治状异质结构的耦合δ-MnO₂/rGO混合阴极表现出卓越的循环性能，在2.0 A g⁻¹下3000次循环后仍保留80.1%的容量。第一性原理计算表明，δ-MnO₂与rGO之间强烈的界面相互作用导致电子转移得到改善，且δ-MnO₂的层状结构得到强化。这项工作建立了一种可行的策略，以减轻水系储能系统中层状氧化锰不利的层状到尖晶石相转变。
