Engineering nanocluster arrays on lotus leaf as free-standing high areal capacity Li-ion battery anodes: A cost-effective and general bio-inspired approach

Bio-inspired materials have received broad attention for energy-storage systems owing to their special properties and low cost. Here, a cost-effective and general strategy is developed for preparing nanocluster arrays on leaves as three-dimensional free-standing Li-ion battery anodes. As a demonstrating case study, an FeCo2O4 nanocluster array is constructed on lotus leaf, which displays a high areal capacity of 2.4 mAh cm−2 after cycling 100 times, and a stable Coulombic efficiency of 99.9%. After long-term 900 cycles at 10 ºC, capacity remains 1.15 mAh cm−2. At a high temperature of 45 ºC, capacity keeps 1.95 mAh cm−2 after cycling 150 times. A recoverable rate-performance after three-rounds measurements is also achieved, enabling the anode to be potentially used at different conditions. In addition, the preparation approach is successfully used for making many other composites including ZnCo2O4, NiCo2O4, CuCo2O4 nanocluster arrays on lotus leaves, and ZnCo2O4, NiCo2O4, CuCo2O4, FeCo2O4 nanocluster arrays on bamboo leaves, displaying a good applicability.