Enhanced Lithium-Ion Battery Electrodes with Metal-Organic Framework Additives Featuring Undercoordinated Zr⁴⁺ Sites.

Abstract

Performances of lithium-ion batteries (LIBs) are dictated by processes of electron-ion separation, transfers, and combination. While carbon additives are routinely used to ensure electronic conductivity, additives capable of simultaneously boosting ion conduction and delivering step-change performance remain elusive. Herein, metal-organic frameworks (MOFs) possessing coordinately unsaturated Zr⁴⁺ sites are exploited as a new material library of electrode additives. The MOFs imbue infused electrolytes with an expanded electrochemical stability window (0 to 5 V vs Li/Li⁺) and enhanced Li⁺ transport efficiency. Mechanistically, strong interactions between Zr⁴⁺ sites and Li⁺ solvation sheaths result in trimmed, anion-fixed, and solvent-separated ion pairs, mitigating electrostatic coupling and enabling efficient Li⁺ translocation in the porous nanospace. Concomitantly, these solvation structural modulations foster interfacial and electrochemical stabilities. When implemented at 1.7 wt.% in graphite and sub-Ah full cell, the MOF additives significantly improved Li⁺ diffusional kinetic, rate capability beyond 2C, and cycling longevity doubling lifespan. This work offers a straightforward yet effective route to remedy the bottlenecks of industrial LIBs.