A team of Chinese scientists has recently developed a high specific energy, flexible all-solid-state sodium battery, according to the Beijing Daily.
The researchers include Wu Zhongshuai from the 2D Materials and Energy Devices Research Group of the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and Yu Yan's team of the University of Science and Technology of China.
Sodium is rich in resources and low in cost, so sodium ion batteries are considered to be ideal devices for large-scale energy storage.
Traditional sodium ion batteries often use liquid electrolytes, which are prone to leakage and combustion. The use of solid sodium ion electrolytes instead of flammable organic liquid electrolytes can effectively improve battery safety.
However, there are problems with the development of solid-state sodium batteries. The solid electrolyte mainly has low ionic conductivity, poor interface contact between the solid electrolyte and the electrode, and a large volume change of the electrode material during the process of de-intercalating sodium ions, resulting in large internal resistance, low capacity, and short life of the solid battery.
Therefore, there is an urgent need to develop more efficient solutions to overcome various problems in solid-state sodium ion batteries to meet the needs of commercial applications.
According to reports, the team on the one hand designed and developed a photo-curing polymerization method to prepare a new polymer solid electrolyte.
It has excellent flexibility; on the other hand, a thin layer of carbon modified sodium vanadium phosphate cathode material is prepared by the sol-gel method, which improves the electron, ion and charge transfer efficiency of the material.
On this basis, the team built an integrated polymer electrolyte / electrode material integrated system, which effectively strengthened the solid-solid interface contact, reduced the battery interface impedance, and developed a flexible solid sodium battery with high specific energy and long life.
The battery can stably charge and discharge cycles 740 times at a rate of 0.5 C (the charge and discharge rate is a measure of the speed of discharge), and the capacity decay rate is only 0.007% each time.
After the battery was left for 3 months, the capacity retention rate was still as high as 95%, indicating that the self-discharge rate was extremely low.
In addition, the soft-packed sodium battery can still provide an energy density of up to 355 Wh / kg after 535 cycles in the flat and folded state.
The design strategy of this work provides a new direction for the development and application of high specific energy flexible all-solid-state sodium batteries.
