The unitized regenerative fuel cell (URFC) is a promising electrochemical device for intermittent renewable energy storage in chemical bonds. However, widespread application has been hindered due to low round-trip efficiencies (RTEs) and disappointing durability, in particular at high rates. Here, we break through that barrier by demonstrating highly efficient, flexible, and stable URFCs via hierarchical design of the multiscale catalyst-layer structures. A more porous and less tortuous Pt and Ir catalyst layer is realized using a doctor blade fabrication method that significantly improves URFC performance. We demonstrate RTEs of 56% and 53% under constant-electrode and constant-gas mode, respectively, while operating at 1000 mA cm⁻², and significantly, a RTE of 45% at 2000 mA cm⁻², achievements that were previously viewed as unfeasible under the onerous demands of URFC operation. At the same time we demonstrate URFCs under both constant-electrode and constant-gas mode operated continuously for over 500 h with negligible degradation. These results demonstrate the viability of applying URFCs for long-term energy storage at previously unattainable efficiencies and cast new light on electrode design and optimization of URFCs.

中文翻译：

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长期稳定存储的高效稳定的联合可再生燃料电池（URFC）的分层电极设计

单元式可再生燃料电池（URFC）是一种有前途的电化学装置，可用于化学键的间歇性可再生能源存储。然而，由于低的往返效率（RTE）和令人失望的耐久性，特别是在高速率下，阻碍了广泛的应用。在这里，我们通过证明高效，灵活和稳定URFCs通过闯关经由多尺度催化剂层结构的分层设计。使用大大提高了URFC性能的刮墨刀制造方法，可以实现多孔性更好，曲折的Pt和Ir催化剂层。我们在恒定电极模式和恒定气体模式下分别在1000 mA cm ^-2的条件下显示RTE分别为56％和53％，在2000 mA cm时显着地显示RTE为45％⁻²，以前在URFC操作的苛刻要求下被视为不可行的成就。同时，我们展示了在恒定电极和恒定气体模式下连续运行超过500小时且降解程度可忽略不计的URFC。这些结果证明了以以前无法达到的效率将URFC用于长期能量存储的可行性，并为URFC的电极设计和优化提供了新的思路。