# A Leap toward Quasi-Solid-State Chloride-Ion Batteries with Metal–Organic Frameworks

## TL;DR

This paper introduces a metal-organic framework as a safe and efficient quasi-solid-state electrolyte for chloride-ion batteries.

## Contribution

The first demonstration of a metal–organic framework as a quasi-solid-state single-ion electrolyte for chloride-ion batteries.

## Key findings

- The MOF MIP-213 shows a chloride ion conductivity of 1.1 × 10–6 S cm–1 at 25 °C.
- The MOF is nonflammable and electrochemically stable up to 4.2 V vs Li+/Li.
- A full cell using MIP-213 maintains >90% Coulombic efficiency over 100 cycles.

## Abstract

The development of solid-state electrolytes is a major
focus in
energy storage, offering improvements in both safety and performance.
In chloride-ion batteries (CIBs), where electrode dissolution in liquid
electrolytes remains a critical challenge, solid-state alternatives
are especially attractive. Herein, we demonstrate for the first time
the suitability of a metal–organic framework (MOF) as a quasi-solid-state
single-ion electrolyte for CIBs. The cationic Al-based MOF MIP-213
([Al18(μ2-OH)24(OH2)12(mdip)6]­6Cl·6H2O) exhibits
a chloride ion conductivity of 1.1 × 10–6 S
cm–1 at 25 °C, is nonflammable, electrochemically
stable up to 4.2 V vs Li+/Li, and enables single-ion
transport in a Li|MIP-213|FeOCl full cell over 100 cycles with Coulombic
efficiency > 90%, while maintaining structural integrity. Although
further optimization of the CIB components will be needed to enable
cycling at higher current regimes and approach practical application,
these findings establish MOFs as promising platforms for designing
stable and efficient quasi-solid-state batteries.