Enhanced ion transport kinetics and sodiophilicity for Na metal batteries enabled by VPO4

Abstract

Na metal is an attractive anode for rechargeable batteries. However, uneven nucleation and deposition may cause dendrite growth and unstable solid electrolyte interphase formation, leading to inferior cycle performance and serious security risks. Herein, we report a stable polyanion-structure of VPO4 with superior transport kinetics for Na metal anodes. The initial sodiation via a solid-solution reaction can retain the stable structure with fast ion transport and enhance the affinity to adsorb Na on the surface of sodiophilic VPO4 skeleton. A reversible cycling behavior of Na metal anode with VPO4 is achieved with an average Coulombic efficiency of 99.63% over 500 cycles. Our study suggests a new direction for constructing sodium metal electrodes via enhancing the internal ion transport kinetics and sodiophilicity to homogeneous Na deposition.