The role of nickel–iron based layered double hydroxide on the crystallinity, electrochemical performance, and thermal and mechanical properties of the poly(ethylene-oxide) solid electrolyte

Abstract

Nickel–iron based layered double hydroxide (NILDH) was used for the first time as an inorganic filler to prepare poly(ethylene-oxide)/nickel–iron based layered double hydroxide (PEO/NILDH) composites to improve the properties of PEO-based solid electrolytes. The SEM micrographs and EDS images confirmed the homogeneous dispersion of NILDH particles in the PEO matrix. The XRD and DSC results indicated that the PEO crystallinity tended to decrease with the increase in the amount of NILDH. Meanwhile, the addition of NILDH promoted the improvement of ionic conductivity for PEO/NILDH composites and the maximum value (1.644 × 10⁻⁴ S cm⁻¹) appeared at the NILDH concentration of 10 wt%. NILDH with a positive charge surface could increase the lithium-ion transference number by attracting and anchoring the anion of LiTFSI. Meanwhile, the formation of amorphous regions around NILDH was beneficial for the Li⁺ ion conduction. Furthermore, the electrochemical stability windows of the composite electrolyte were increased to 5.2 V after the addition of NILDH, and the all-solid-state lithium battery using this composite electrolyte showed a specific capacity of 148 mA h g⁻¹ and better cycling performance. The tensile strength of PEO/NILDH composites was enhanced when NILDH was introduced into the PEO matrix with a filler loading of not more than 10 wt%. The remarkable properties of the PEO/NILDH composite make it a potential solid electrolyte material for lithium-ion batteries.