N7-(carboxymethyl)guanine-lithium crystalline complex: a bioinspired solid electrolyte

Abstract

Electrochemical device with components having direct significance to biological life processes is a potent futuristic strategy for the realization of all-round green and sustainable development. We present here synthesis design, structural analysis and ion transport of a novel solid organic electrolyte (G7Li), a compound reminiscent of ion channels, derived from regioisomeric N7-guanine-carboxylate conjugate and Li-ions. G7Li, with it’s in-built supply of Li⁺-ions, exhibited remarkably high lithium-ion transference number (= 0.75) and tunable room temperature ionic conductivity spanning three decades (≈10⁻⁷ to 10⁻³ Ω⁻¹ cm⁻¹) as a function of moisture content. The ionic conductivity show a distinct reversible transition around 80–100 °C, from a dual Li⁺ and H⁺ (<100 °C) to a pure Li⁺ conductor (>100 °C). Systematic studies reveal a transition from water-assisted Li-ion transport to Li hopping-like mechanism involving guanine-Li coordination. While as-synthesized G7Li has potential in humidity sensors, the anhydrous G7Li is attractive for rechargeable batteries.