Room temperature Na-ion batteries for wind energy storage
Electric energy storage (EES) is a key enabler for the use of wind energy. EES for wind energy storage should have high round-trip energy efficiency, long deep-cycle life, low operation and maintenance cost, high reliability, long durability and safety. Current well-developed battery technology cannot meet the durability and cost requirements for wind energy storage. In our group, a Na-ion battery using Sn anode and Na2S cathode has been developed. Compared to the Li-ion battery, the Na-ion battery is much cheaper. Different from the high temperature (300oC) Na/S batteries which have been considered as a promising candidate for renewable energy storage, Sn/Na2S Na-ion batteries can operate at room temperature. Sn and S have the highest capacities of all anodes and cathodes reported in open literature for Na-ion batteries.
Na-ion insertion/extraction behavior and cycling stability of S cathodes is shown in Figure 1. Na2S cathode can provide 220mAh/g capacity with excellent cycle stability. Since the sulfur content in S/C is around 40%, the capacity of Na2S is around 550mAh/g. Figure 2 shows the charge/discharge performance of Sn anodes. The capacity of Sn anodes can reach 300 mAh/g. The electrochemical performance of Sn/Na2S is currently being tested in Dr. Wang’s Lab. Dr. Wang’s group is also exploring other cathodes (Na0.44MnO2, NaCrO2, NaFePO4) for the Na-ion battery.
Figure 1. Charge/discharge curves (a) and cycling stability of S cathode at 0.5C rate.
Figure 2. Charge/discharge curves of Sn anodes at 0.1C rate.