Regulating lithium-ion flow by piezoelectric effect of the poled-BaTiO3 film for dendrite-free lithium metal anode

Dendritic growth is regarded as the intrinsic cause of failure for the lithium metal rechargeable batteries, which blame on the uneven lithium-ion flux induced by the fragile native solid electrolyte interface (SEI) film. Herein, a functional SEI film is composed of BaTiO3 (BTO) dipole in polyacrylonitrile (PAN) matrix, to regulate lithium-ion flux through piezoelectric effect. It is found that, piezoelectric effect of the poled BTO film will induce a reversed local electric field on the dendrites bulge, thus reducing the aggregation of lithium-ion flow and slowing down dendrite growth. Moreover, the PAN matrix of the BTO film exhibited outstanding mechanical property of toughness and long fatigue lifespan, buffering volume change of lithium metal electrode during the plating/striping process. Under the effect of the poled BTO film, the lithium electrode achieved a flatter and smoother surface than that of native SEI film even after depositing a large area capacity of 10 mA h cm−2. Consequently, The Li||Poled-BTO-Cu half-cell delivered 94% coulombic efficiency over 180 cycles. Furthermore, the Poled-BTO-Li||FeLiPO4 could maintain the capacity at 110 mA h g−1 after 350 cycles.