In-situ fabrication of Na3V2(PO4)3/C thin-film electrode for high-performance sodium-ion batteries

Compared with the traditional powder electrode, the active material/carbon composite thin-film electrode has many advantages in binder-free, flexible and electrochemical performance. However, typical fabrication methods of film electrodes, such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), are complex and costly. Herein, an accessible and economical spin-coating method is proposed to in-situ fabricate Na3V2(PO4)3 film with different thicknesses on graphite discs, whose electrochemical performances are inves-tigated in sodium-ion batteries. The results show that a specific capacity of 167 mA h g-1 at 1 C is obtained in the thinner electrode thanks to the contribution of the graphite substrate. It is also found that the specific capacity of the electrode decreases as the film becomes thicker while the cycling stability and electrochemical kinetics are significantly improved. The capacity retention of 93.8 % is achieved in the thicker electrode after 5000 cycles at 10 C. This work presents a novel idea for designing and building high-performance, economical, and environ-mentally friendly energy storage devices.