Conformally reactive interphase enables excellent kinetics and cyclability in quasi-solid-state sodium metal battery

The rational design of flexible and robust anode -electrolyte interface is of great significance for extending the cycle life and improving the kinetics performance for sodium metal batteries (SMBs). Herein, a conformally reactive solid -electrolyte interphase (SEI) is constructed through a spontaneous absorption-oligomerization strategy in a quasi -solid-state polymer electrolyte (QSE-T). The polymeric network in the QSE-T system ensures a stable environment with high Na + transfer number to suppress Na dendrite growth and chemical corrosion. Simultaneously, the reactive SEI is consisted of inorganic NaF and low crosslinked O -B -O and O -B -F segments derived from the 4-trifluoromethylphenylboronic acid (TFPBA) additive, which exhibits lower Na + diffusion -barriers, and accommodates the ever-changing quasi -solid interface during cycling. Consequently, the NVP||QSE-T||Na cells exhibit ultra -stable cycling performance and high rate capability, with a high initial capacity of 95.1 mAh g -1 at a high rate of 5 C and a capacity retention rate of 86.6 % after 12,000 cycles.