Enhanced Electrochemical Performance of Li₃V₂(PO₄)₃/C Coated with Li Fast Ion Conductive Li₇La₃Zr₂O₁₂

Abstract

Li7La3Zr2O12-coated Li3V2(PO4)3/C (LLZO-coated LVP/C) has been synthesized via a conventional sol-gel method, in which LLZO as the fast Li-ion conductor and carbon as the mixed coating with excellent electronic conductivity could enhance the transport of both electrons and Li-ions at the electrode's surface. X-ray diffraction (XRD) and transmission electron microscopy (TEM) with energy dispersive spectrometer (EDS) have been performed to prove the existence of LLZO on the surface of LVP. The valence states of the La and Zr elements are investigated by X-ray photoelectron spectroscopy (XPS). The capacity retention rates of LVP/C and LLZO-coated LVP/C after 100 cycles at 0.5C are 75.7% and 83.4%, respectively. Besides, the LLZO-coated LVP/C exhibits a specific discharge capacity of 161 mA h g−1 at 0.1C and 95 mA h g−1 at 5C at the voltage range of 3.0–4.8 V (vs Li+/Li), respectively. The superior electrochemical performance of LLZO-coated LVP/C can contribute to two aspects as follows: (1) LLZO coating provides a chemically stable layer which effectively reduces the chemical reactions between the active material and the electrolyte; (2) Compared with the uncoated LVP/C, the ionic conductivity of LLZO-coated LVP/C increases which is proved by the results of CV and GITT. Thus, we believe that the synthesis strategy of LLZO or other solid-state electrolytes and carbon hybrid coating could be employed to develop other cathode materials for their application in power lithium ion battery.

CoS2Coatings for Improving Thermal Stability and Electrochemical Performance of FeS2Cathodes for Thermal Batteries

“…24 It is due to the fact that the electrochemical reaction is primarily a surface reaction, and the surface state of the cathode material largely determines its properties. [25][26][27][28][29] Therefore, in this study, a thin CoS 2 layer was successfully coated on FeS 2 via the hydrothermal method and a subsequent heat-treatment. The CoS 2 coating improved the thermal stability and electrochemical performance of FeS 2 .…”

Three‐Dimensional Holey Graphene Enwrapped Li3V2(PO4)3/N‐Doped Carbon Cathode for High‐Rate and Long‐Life Li‐Ion Batteries

“…Figure 4c shows the CV curves of LVPNCHG and LVPNC in 3.0–4.8 V at 0.2 mV s −1 , and the observed oxidation/reduction peaks correspond to plateaus during charge/discharge processes. Obviously, the peaks difference during oxidation/reduction for LVPNCHG is smaller than LVPNC, indicating LVPNCHG has less polarization behavior and is more favorable than LVPNC in the electrochemical process [40,41] …”

“…Obviously, the peaks difference during oxidation/reduction for LVPNCHG is smaller than LVPNC, indicating LVPNCHG has less polarization behavior and is more favorable than LVPNC in the electrochemical process. [40,41] Figure 4d shows the long-term cycling performance of LVPNCHG and LVPNC at 10 C at 3.0-4.8 V. The first 3 cycles at 0.2 C were conducted to activate the electrodes. LVPNCHG delivered about 140 mAh g À 1 in the initial several cycles, keeping 101 mAh g À 1 after 2000 cycles (70.2 % capacity retention) and 92 mAh g À 1 after 4000 cycles (63.9 % capacity retention), which was higher than LVPNC with 57 mAh g À 1 after 2000 cycles (43.3 % capacity retention).…”