Unlike conventional electrolytes, ionic liquid (IL)-based electrolytes offer higher thermal stability, acceptable ionic conductivity, and a higher electrochemical stability window (ESW), which are indispensable for the proper functioning of Li-ion batteries. In this study, fluorine-free electrolytes are prepared by mixing the lithium furan-2-carboxylate [Li(FuA)] salt with the tetra(n-butyl)phosphonium furan-2-carboxylate [(P₄₄₄₄)(FuA)] IL in different molar ratios. The anion of these electrolytes is produced from biomass and agricultural waste on a large scale and, therefore, this study is a step ahead toward the development of renewable electrolytes for batteries. The electrolytes are found to have T_onset higher than 568 K and acceptable ionic conductivities in a wide temperature range. The pulsed field gradient nuclear magnetic resonance (PFG-NMR) analysis has confirmed that the (FuA)⁻ anion diffuses faster than the (P₄₄₄₄)⁺ cation in the neat (P₄₄₄₄)(FuA) IL; however, the anion diffusion becomes slower than cation diffusion by doping Li salt. The Li⁺ ion interacts strongly with the carboxylate functionality in the (FuA)⁻ anion and diffuses slower than other ions over the whole studied temperature range. The interaction of the Li⁺ ion with the carboxylate group is also confirmed by ⁷Li NMR and Fourier transform infrared (FTIR) spectroscopy. The transference number of the Li⁺ ion is increased with increasing Li salt concentration. Linear sweep voltammetry (LSV) suggests lithium underpotential deposition and bulk reduction at temperatures above 313 K.