Self-standing oxygen-deficient α-MoO3-x nanoflake arrays as 3D cathode for advanced all-solid-state thin film lithium batteries

Compared with the planar two-dimensional (2D) all-solid-state thin film batteries (TFBs), three-dimensional (3D) all-solid-state TFBs with interdigitated contact between electrode and electrolyte possess great advantage in achieving both high energy and power densities. Herein, we report a facile fabrication of vertically aligned oxygen-deficient α-MoO 3-x nanoflake arrays (3D MO x ) using metal Mo target by direct current (DC) magnetron sputtering. By utilizing the 3D MO x cathode, amorphous lithium phosphorus oxynitride solid electrolyte, and lithium thin film anode, 3D solid-state TFBs have been successfully fabricated, exhibiting high specific capacity (266 mAh g −1 at 50 mA g −1 ), good rate performance (110 mAh g −1 at 1000 mA g −1 ), and excellent cycle performance (92.7% capacity retention after 1000 cycles) in comparison with the 2D TFBs using the planar MO x thin film as cathode. The superior electrochemical performance of the 3D TFBs can be attributed to the 3D architecture of the cathode, maximizing the cathode/electrolyte interface while retaining the short Li + diffusion length. The charge/discharge measurements of the 3D MO x cathode in liquid electrolyte, however, exhibit fast capacity fading, demonstrating the advantage of using transition metal oxide as cathode in solid-state batteries.