Pseudocapacitive lithium-rich disordered rock salt vanadium oxide with 3D lithium-ion transport pathways for high-performance lithium-ion capacitor

Pseudocapacitive materials with high-rate behavior of lithium-ion charge storage offer a pathway to narrow the kinetics gap with capacitive porous carbon cathode toward lithium-ion capacitors both with high energy and high power densities. However, most of pseudocapacitive materials are subject to their relatively high redox potential , thus resulting in an undesirable decrease in energy density . Here, we demonstrate that lithium-rich disordered rock salt vanadium oxide (DRX-Li 3 V 2 O 5 ), electrochemically transformed from V 2 O 5 bulk, exhibits typical pseudocapacitive behaviors within a low working potential range between 0.1 and 2.0 V (vs. Li/Li + ). The pseudocapacitive behaviors of DRX-Li 3 V 2 O 5 mainly arise upon a percolating network that offers three-dimensional Li  +  transport pathways confirmed by Monte Carlo simulations . When the V 2 O 5 bulk precursor is replaced by V 2 O 5 nanosheets , as-obtained DRX-Li 3 V 2 O 5 electrode displays a nearly symmetrical cyclic voltammetry curve, suggesting an ideal pseudocapacitive behavior. A lithium-ion capacitor further assembled by this pseudocapacitive DRX-Li 3 V 2 O 5 anode, yields a cell voltage of 4.0 V, a maximum energy density of 186 Wh kg −1 and a maximum power density of 51,680 W kg −1 as well as long-term cycling life over 30,000 cycles, which are higher than or comparable to that of the state-of-art lithium-ion capacitors based on graphite and other pseudocapacitive materials.