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Scientists develop high specific energy all-solid-state sodium battery
[ Instrument Network Instrument R & D ] Recently, the team of Wu Zhongshuai, a researcher of the two-dimensional materials and energy devices research group of the Dalian Institute of Chemical Physics, the Chinese Academy of Sciences, and the team of Professor Yu Yan of the University of Science and Technology of China, and Yao Xiayin of the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences An integrated integrated system of polymer solid electrolyte and positive electrode material was constructed, which effectively reduced the solid-solid interface impedance, significantly improved the transmission efficiency of electrons, ions and charges, and developed a high specific energy and flexible all-solid-state sodium battery.
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, the development of solid-state sodium batteries also has problems: (1) the ionic conductivity of the solid-state electrolyte is low; (2) the interface contact between the solid-state electrolyte and the electrode is poor; (3) the volume of the electrode material during de-intercalation of sodium ions Large changes lead to large internal resistance, low capacity, and short life of solid-state batteries. 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.
On the one hand, the team designed and developed a photocuring polymerization method to prepare a new polymer solid electrolyte. The obtained electrolyte has an ionic conductivity of up to 10-4 S / cm at room temperature, and has excellent flexibility; On the other hand, a thin layer of carbon (5 nm) modified sodium vanadium phosphate cathode material was prepared by the sol-gel method, which improved 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 be stably cycled 740 times at a rate of 0.5 C, 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. The soft-packed sodium battery can still provide an energy density of up to 355 Wh / kg after 535 cycles in the flat and bent 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.