A High-Voltage and Ultralong-Life Sodium Full Cell for Stationary Energy Storage

Recently, there has been great interest in developing advanced sodium-ion batteries for large-scale application. Most efforts have concentrated on the search for high-performance electrode materials only in sodium half-cells. Research on sodium full cells for practical application has encountered many problems, such as insufficient cycles with rapid capacity decay, low safety, and low operating voltage. Herein, we present a layered P2-Na0.66 Ni0.17 Co0.17 Ti0.66 O2 , as both an anode (ca. 0.69 V versus Na(+) /Na) and as a high-voltage cathode (ca. 3.74 V versus Na(+) /Na). The full cell based on this bipolar electrode exhibits well-defined voltage plateaus near 3.10 V, which is the highest average voltage in the symmetric cells. It also shows the longest cycle life (75.9 % capacity retention after 1000 cycles) in all sodium full cells, a usable capacity of 92 mAh g(-1) , and superior rate capability (65 mAh g(-1) at a high rate of 2C).