Morphology-controlled metal–organic frameworks as molecular traps for enhanced ion dynamics in practical semi-solid lithium metal batteries

Abstract

Controlling electrostatic interactions between charged molecules is crucial to enabling advanced batteries with reliable lithium (Li)-ion conductors. To address this issue, herein, we present a class of morphology-controlled metal–organic frameworks (MOFs) that serve as Li+ boosting molecular traps for fast Li+ conduction. A rod-like MOF is incorporated into semi-interpenetrating polymer networks to construct Li+ boosting fluidic nanochannels, which enable fast Li+ transport (σ = 1.5 mS cm−1, tLi+ = 0.76) through the ionic pathway. Molecular dynamics simulations further elucidate the Li+ transport mechanism in these MOF-based molecular traps. This unusual Li+ conduction behavior of MOF-based semi-solid electrolytes suppresses the anion-triggered ion concentration gradient and facilitates the electrochemical reaction kinetics at the electrodes, ultimately improving the rate performance and cycling retention of Li-metal cells (consisting of LiNi0.7Co0.2Mn0.1O2 cathodes and Li-metal anodes). Notably, a scalable pouch-type semi-solid Li-metal cell provides stable cycling performance for realistic batteries, exceeding those of previously reported Li batteries including porous crystalline frameworks.