Polyoxometalates with multiple redox reactions have been reported as electron/ion sponges for lithium-ion storage applications. Here we introduce a vanadium-based polyoxometalate, Na7H2[PV14O42] (NPV), as an anode material for Lithium-ion batteries (LIBs). NPV exhibits a high reversible capacity up to 687 mA h g−1 at 100 mA g−1 with a good capacity retention of ~80% after 150 cycles. In operando synchrotron X-ray absorption near edge structure reveals the change of the valences of vanadium from V4+ to V1.87+, indicating that it can transfer at least 30 electrons per molecule which leads to high capacity. In operando synchrotron X-ray diffraction confirms the crystal structure of NPV electrode converts to amorphous during charge/discharge processes. Therefore, the charge storage mechanism of NPV could be further proposed that Li ions insert into amorphous NPV electrode continuously and react with [PV14O42]9- molecules, and [PV14O42]9- is like an electron/ion sponge which can store at least 30 electrons.