A Lithium-Ion Pump Based on Piezoelectric Effect for Improved Rechargeability of Lithium Metal Anode

Lithium metal is widely studied as the "crown jewel" of potential anode materials due to its high specific capacity and low redox potential. Unfortunately, the Li dendrite growth limits its commercialization. Previous research has revealed that the uniform Li-ion flux on electrode surface plays a vital role in achieving homogeneous Li deposition. In this work, a new strategy is developed by introducing a multifunctional Li-ion pump to improve the homogenous distribution of Li ions. Via coating a β-phase of poly(vinylidene fluoride) (β-PF) film on Cu foil (Cu@β-PF), a piezoelectric potential across such film is established near the electrode surface because of its piezoelectric property, which serves as a driving force to regulate the migration of Li ions across the film. As a result, uniform Li-ion distribution is attained, and the Cu@β-PF shows coulombic efficiency around 99% throughout 200 cycles. Meanwhile, the lithium-sulfur full cell paired with Li-Cu@β-PF anode exhibits excellent performance. This facile strategy via regulating the Li-ion migration provides a new perspective for safe and reliable Li metal anode.