Tantalum oxide nanosheets/polypropylene composite separator constructing lithium-ion channels for stable lithium metal batteries

Developing next-generation high-energy–density rechargeable batteries is pivotal to solve the growing demand for sustainable energy. Lithium metal battery (LMB) is the representative in post-lithium-ion battery era. However, uncontrollable growth of Li dendrites and low Coulombic efficiency (CE) prevent it from practical applications in LMBs. Here, a multifunctional tantalum oxide nanosheets/polypropylene (TaO 3 @PP) composite separator is developed to regulating ion transport in atomic scale. The TaO 3 coating can improve the wettability and thermal stability of the PP separator. The openings of the nanomesh structure provide Li + channels to allow efficient lithium-ion transport. The electrostatic attraction force between TaO 3 nanosheets and Li + and the electrostatic repulsion force between TaO 3 nanosheets and anions ensuring the fast Li + diffusion and low concentration polarization. The TaO 3 @PP separator can regulate Li + distribution and promote uniform lithium deposition, inhibiting the Li dendrite growth. Thus, the composite separator achieves a high Li-ion transference number of 0.72. The LiFePO 4 ||Li cell with the composite separator delivers high discharge capacity of 145 mAh g −1 over 500 cycles at 0.5 C.