Huge Electron Sponge of Polyoxometalate toward Advanced Lithium-Ion Storage

The huge polyoxometalate, ${Na}_{48}\left[H_x{Mo}_{256}^{VI}{Mo}_{112}^V{O}_{1032}{\left(H_{2}O\right)}_{240}{\left({\text{SO}}_4\right)}_{48}\right]$ ({Mo₃₆₈}), which can be prepared by a facile solution process and can be applied in lithium-ion storage applications as the anode. The large and open hollow nanostructure is promising to store a larger number of lithium ions and expedite the diffusion of lithium ions. A single {Mo₃₆₈} nanocluster can transfer 624 electrons, referred to as a “huge electron sponge”. Pure {Mo₃₆₈} without any support materials exhibits very high capacities of 964 mA h g^–1 with hardly any decay for 100 cycles at 0.1 A g^–1 and still maintains 761 mA h g^–1 after 180 cycles at 0.5 A g^–1, indicating great cycling stability. The {Mo₃₆₈} anode provides excellent rate performance and reversibility during the lithiation/delithiation processes, which are contributed by both the diffusion-controlled process and the capacitive process. The capacitive contribution can reach 71.7% at a scan rate of 2 mV s^–1. The high D_Li⁺ value measured by GITT confirms the fast reaction kinetics of the {Mo₃₆₈} electrode. The {Mo₃₆₈}//NCM111-A full cell is practically applied to light LED lamps. These investigations indicate that {Mo₃₆₈} nanoclusters are advanced energy storage materials with high capacities, fast charge transfer, and low-cost mass production for lithium-ion storage. Moreover, {Mo₃₆₈} should be considered a clean energy material because there is no production of environmental pollution during the charge/discharge processes.