Carbon decorated Li_3V_2(PO_4)_3 for high-rate lithium-ion batteries:Electrochemical performance and charge compensation mechanism

摘要

Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_3 V_2(PO_4)_3 is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_3 V_2(PO_4)_3(LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.