Y. Yao, Z. Wei, H. Wang, H. Huang, Y. Jiang, X. Wu, X. Yao*, Z.-S. Wu*, Y. Yu*

Advanced Energy Materials, 2020, 10, 1903698.

DOI: 10.1002/aenm.201903698 [PDF]

All solid-state sodium batteries(ASSBs)have attracted considerable attentiondue to their enhanced safety,long lifespan and high energy density. However,several challenges have plagued the development of ASSBs, especially the relatively low ionic conductivity of solid-state electrolytes (SSEs),large interfacial resistance and low stability/compatibility between SSEs and electrodes. Here, a high-performance all solid-state sodium battery (NVP@C|PEGDMA-NaFSI-SPE|Na)is designed by employing carbon coated Na₃V₂(PO₄)₃composite nanosheets (NVP@C) as the cathode, solvent-free solid polymer electrolyte (PEGDMA-NaFSI-SPE) as the electrolyte and metallic sodium as the anode. Theintegrated electrolyte and cathode system prepared by thein-situpolymerization process exhibits high ionic conductivity (~10^-4S cm^-1at room temperature) and integrate electrolyte/electrode interface. Benefiting from these merits, the soft-pack ASSB (NVP@C|PEGDMA-NaFSI-SPE|Na)delivers excellent cycling life over 740 cycles (capacity decay of only 0.007% per cycle)and maintains 95% of the initial reversible capacity with almost no self-discharge even after resting for 3 months. Moreover, the bendable ASSB exhibits a highcapacity of 106 mAh g^-1(corresponds to energy density of ~355Wh kg^-1) at 0.5 C despite undergoing repeated bending for 535 cycles. This work offersanew strategy to fabricate high-performance flexible ASSBs with long lifespan and excellent flexibility.