A High-Performance Sodium-Ion Full Cell with a Layered Oxide Cathode and a Phosphorous-Based Composite Anode

A low-cost sodium-ion full cell with a O3-type layered Na[Cu 0.2 (Fe 1/3 Mn 2/3 ) 0.8 ]O 2 cathode and an alloy-type P-TiP 2 -C anode is presented. The cathode is synthesized by an oxalate coprecipitation method and optimized cathodes shows a high specific capacity of 135 mAh g −1 at 0.1C rate with a high rate capability of 90 mAh g −1 at 1C rate and 70 mAh g −1 at 2C rate with good cyclability. The full cell exhibits better capacity retention than the half cell with the cathode due to the elimination of the degradation caused by sodium-metal anode. The dramatically enhanced electrochemical performance of the Na[Cu 0.2 (Fe 1/3 Mn 2/3 ) 0.8 ]O 2 / P-TiP 2 -C full cell compared to that of the sample with no Cu is attributed to the structural stabilization imparted by Cu by suppressing the phase change from the O3 structure to the P3 structure during cycling.