Structural trade-off regulation of composite aerogels via “island-bridge” design for advanced nickel-iron batteries

Nickel-iron batteries (NIBs) as typical aqueous batteries have ideal electrochemical performance in theory, making them potential candidates for power supply in specific conditions. However, they still face numerous thorny practical problems, including unsatisfactory durability and undesirable lifespan of anodes. Here, we put forward a new “island-bridge” design for building up rational anode networks by architecting active nanoparticle “islands” and conductive nanosheet “bridges” to realize trade-off strategy in electrochemistry. In comparison with normally-designed metal-graphene composites which are composed of dominate graphene substrates with metal-based additives, “island-bridge” design leads to optimized balance of abundant redox sites and enough conductive connections. As a result, the aerogels stemmed from “island-bridge” design display outstanding anode performance for NIBs with large capacity, high rate capability and long lifespan, which are far more superior than graphene-dominated composite anodes and neat metal oxides anodes. Additionally, theoretical calculations validate the mechanism of advantageous “island-bridge” design that it endows the anodes with numerous active sites, high-speed electron pathways and suitable ion-penetrable nanosized-pores. This work paves a way to take insights into micro-nano structured composite electrodes, providing a feasible way to prepare high-performance anodes for practical aqueous energy storage.