LAUSR

Highly efficient, clean, and sustainable electrochemical energy storage technologies have been investigated extensively to counter the shortage of fossil fuels and increasingly prominent environmental problems. Supercapacitors (SCs) have received wide attention as critical devices for electrochemical energy storage because of their rapid charging–discharging capability and long life cycle. Various transition metal oxides (TMOs), such as MnO2, NiO, Co3O4, and CuO, have been extensively studied as electrode materials for SCs. Compared with carbon and conducting polymers, TMO materials can achieve higher specific capacitance. For further improvement of electrochemical performance, hierarchically nanostructured TMO materials have become a hot research area for electrode materials in SCs. The hierarchical nanostructure can not only offer abundant accessible electroactive sites for redox reactions but also shorten the ion diffusion pathway. In this review, we provide an overall summary and evaluation of the recent progress of hierarchically nanostructured TMOs for SCs, including synthesis methods, compositions, structures, and electrochemical performances. Both single-phase TMOs and the composites based on TMOs are summarized. Furthermore, we also prospect the developing foreground of this field. In this view, the important directions mainly include: the nanocomposites of TMOs materials with conductive materials; the cobalt-based materials and the nickel-based materials; the improvement of the volume energy density, the asymmetric SCs, and the flexible all-solid-state SCs.摘要为了应对化石燃料短缺与日益严重的环境污染问题, 开发高效、清洁、可持续的电化学储能技术已迫在眉睫. 超级电容器, 由于其 功率密度高、充放电时间短、循环寿命长等特点, 已得到广泛关注. 多种过渡金属氧化物已被作为超级电容器电极材料进行了深入研究. 为了进一步提高性能, 具有多级纳米结构的过渡金属氧化物材料已成为目前超级电容器领域的研究热点. 多级纳米结构不仅可以为电化 学反应提供更多活性位点, 同时还可以缩短离子的传输路径. 本综述对多级纳米结构过渡金属氧化物在超级电容器电极材料方面的应用, 进行了系统的总结与评价, 主要包括: 合成方法、成分、结构和电化学性能. 此外, 对该领域的进一步发展进行了展望.