Positive Surface Pseudocapacitive Behavior-Induced Fast and Large Li-ion Storage in Mesoporous LiMnPO @C Nanofibers.

Olivine-structured LiMnPO (LMP) is an efficient Li host owing to its high theoretical energy density and thermal stability. However, its poor ionic and electronic conductivity severely hinder its practical application. Herein, one-dimensional (1D) LMP@C nanofibers with in situ created 3D mesoporous architecture are reported and the charge-storage behavior is addressed. Ultrafine LMP nanoparticles are homogeneously confined in the nanofibers with interconnected and exposed mesoporous intersections, facilitating the electronic/ionic transportation and retarding the pulverization/fracture of electrodes. Remarkably, the hierarchical construction promotes a certain degree of pseudocapacitive contribution. The diffusion-controlled battery-type and surface-controlled capacitive faradaic redox processes act synergistically, giving new insights into Li-ion storage cathode materials to reach the common goal of high energy density and power density simultaneously. The current separation technique suggests surface-dominated pseudocapacitance as the major Li storage mechanism at high rates, which is regarded as an efficient way to improve the rate performance. Hence, the as-prepared LMP@C nanofibers could deliver a high reversible capacity of 149.8 mAh g with 92 % charge retention over 300 cycles at 0.2 C (1 C=171 mA g ). Even at a high rate of 5 C, a capacity of 63.1 mAh g is retained after 2000 cycles with an exceptional cyclic stability.