Hybrid electrolytes with an ultrahigh Li-ion transference number for lithium-metal batteries with fast and stable charge/discharge capability

Abstract

Electrolytes with a high ionic transference number hold great promise for reducing battery polarization and achieving safe energy storage. Herein, single-ion electrolytes containing α-LiAlO₂@γ-Al₂O₃ nanosheets as fillers in PVDF-HFP are prepared. The α-LiAlO₂@γ-Al₂O₃ nanosheets show excellent anion-anchoring ability due to the high adsorption energy to anions on the surfaces, leading to a remarkable lithium-ion (Li⁺) transference number of 0.92 and a great ionic conductivity of 0.85 mS cm⁻¹ at room temperature. Such a high Li⁺ transference number effectively alleviates the concentration gradient polarization, improves the homogeneous Li⁺ deposition, and suppresses the Li dendrite growth. As a result, the symmetric Li‖Li cell realizes superior interfacial stability and dendrite suppression capability for 1000 h at a current density of 0.5 mA cm⁻². Moreover, the LiNi_0.85Co_0.05Al_0.1O₂‖Li and LiFePO₄‖Li batteries with the electrolyte demonstrate significantly improved specific capacities and excellent cycling durabilities at high rates. Especially, the LiFePO₄‖Li battery exhibits a capacity retention of 88% over 2000 charge/discharge cycles at a rate of 2C. This work offers a strategy for designing single-ion electrolytes toward high-performance energy storage.