Electrochemical properties of Li metal batteries with P(PEGMA)-coated lithium trivanadate cathode and Li powder anode

Ionic conductive poly(poly(ethylene glycol) methyl ether methacrylate) (hereafter polymer) was coated onto a lithium trivanadate (LiV₃O₈) cathode by using an electrostatic spray deposition method in an effort to improve the ionic conductivity and prevent dissolution of vanadium into the electrolyte. The coating layer on the LiV₃O₈ electrode was identified by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. Polymer was uniformly coated on the LiV₃O₈ electrode with a thickness of about 40 nm. Lithium powder, synthesized by the droplet emulsion technique, was used as the anode. Electrochemical charge-discharge tests showed that the cell based on the polymer-coated LiV₃O₈ cell exhibited an initial specific capacity of 186 mAh/g and the capacity retentions of the polymer-coated LiV₃O₈ after 100cycles was 87%, which is far improved that of uncoated cell (65%). Also, the coated cell showed 81% of the capacity retention after 300 cycles at 2 C-rate. These results demonstrate that the polymer coating on LiV₃O₈ is effective for suppressing capacity fading at high C-rate.