Asymmetric polymer solid electrolyte constructed by dopamine-modified Li1.4Al0.4Ti1.6(PO4)3 for dendrite-free lithium battery

Abstract

Solid polymer electrolyte (SPE) is an ideal substitute for routine liquid electrolyte for next-generation safety lithium (Li) batteries. Nevertheless, SPE cannot effectively impede Li dendrite growth due to the poor mechanical strength, which prevents its practical applications. Herein, an asymmetric sandwich solid electrolyte constructed by dopamine-modified Li_1.4Al_0.4Ti_1.6(PO₄)₃ (PDA@LATP) on one side was prepared by solution casting method. The asymmetric electrolyte exhibits admirable ionic conductivity (1.2 × 10^–4 S cm⁻¹ at 25 °C), high ionic transference number (0.47), wide voltage window (4.6 V vs. Li/Li⁺) and good thermal stabilities. The PDA@LATP can not only impede Li dendrite growth, but also avoid the LATP reaction with Li anode. The assembled solid-state LiFePO₄|Li battery assembled with asymmetric solid electrolyte delivers a satisfactory capacity retention up to 88.2% after 300 cycles at 0.5 C and under 25 °C (88.1% after 100 cycles at 0.5 C and under 70 °C). The asymmetric design of solid electrolyte provides a promising options for realizing safe energy storage systems.

Graphical abstract

We propose an asymmetric sandwich solid electrolyte, which can enable LiFePO₄|Li battery stably and safely cycled at 25 °C and 70 °C, respectively, with excellent ionic conductivity, electrochemical and thermal stability. This asymmetric electrolyte ensures the inhibition of Li dendrites and stable electrolyte/anode interface.