Development of Sodium-Ion Batteries for Grid-Scale Energy Storage

Abstract

With the tremendous development of renewable energies such as solar and wind powers, the smooth integration of their energies into the grid, thus improving the grid reliability and utilization, critically needs large-scale energy storage systems with low cost, long-life, high efficiency and high safety. Among the various energy storage technologies, electrochemical approach represents one of the most promising means to store the electricity in large-scale because of the flexibility, high energy conversion efficiency and simple maintenance. Due to the highest energy density among practical rechargeable batteries, lithium-ion batteries have been widely used in the portable electronic devices and would undoubtedly be the best choice for the electric vehicles. However, the rarity and non-uniform distribution of lithium in the Earth’s crust may not simultaneously support these two important application areas: electric vehicles and renewable energy. In this regard, room-temperature sodium-ion batteries with lower energy density compared with lithium-ion batteries have been reconsidered particularly for renewable energy, where cost and cycle life are more critical factors than energy density owing to the abundant sodium resources (2.75%) and low cost as well as similar “rocking-chair” sodium storage mechanism as lithium. More importantly, we can use Na+ions as the charge carrier to explore new chemistry and new materials to further decrease the cost. For example, sodium cannot form the alloy with aluminum, therefore aluminum foil can be used as the current collector for the anode without the overdischarge problem. In this talk, I will present our recent research progress on the sodium-ion batteries from IoP-CAS. In particular, I will focus on a series of air-stable and Ni-/Co-free Na-Cu-Fe-Mn-O (e.g., Na0.9Cu0.2Fe0.3Mn0.5O2) cathode and a superior low cost amorphous carbon anode made from pitch and lignin. Finally, the prototype sodium-ion batteries based on these cathode and anode materials will also be demonstrated to have promising practical application.