Composite polymer electrolytes reinforced by two-dimensional layer-double-hydroxide nanosheets for dendrite-free lithium batteries

Abstract

Applications of polymer electrolytes in lithium batteries are lagged by the low ionic conductivity and lithium-ion transference number, and polymer electrolytes are mechanically weak to suppress lithium dendrites. Herein, two-dimensional layer-double-hydroxide (2D LDH) nanosheets are introduced into polyethylene oxide (PEO) as fillers for the first time. After blending with 2D LDH fillers, the composite polymer electrolyte (CPE) exhibits an optimized conductivity with a lithium-ion transference number of 0.42. Additionally, the mechanical strength and electrochemical stability of the CPE at high voltages are improved. More importantly, the CPE shows a markedly enhanced stability against dendritic lithium, and the current density for dendrite-free Li plating/stripping in the CPE arises to 800 μA cm−2 at 60 °C. Solid-state lithium batteries based on the PEO/LDH CPEs show an initial discharge capacity of ~138 mA h g−1 with a capacity retention of 88% after 100 cycles at 0.2 C and 60 °C.