Chloroaluminate Molten Salts for Low-Temperature Electrochemical Recycling of Layered Metal Oxide Cathodes.

Abstract

Electrochemical recycling (ECR) offers a promising strategy that harnesses renewable energy to deconstruct spent layered metal oxides (LMOs). However, current ECR approaches are limited to high-temperature operation (up to 750 °C) employing alkali carbonate or chloride melts as electrolytes, leading to high energy consumption for heat input. Here, this study proposes a low-melting-point alkali chloroaluminate melt electrolyte composed of AlCl₃-LiCl, enabling ECR electrolysis at a temperature as low as 150 °C. Owing to the high solubility of O^2- charge carrier in alkali chloroaluminate melt, LMO cathode undergoes electrochemical reductive de-structuring to yield elemental transition metals and lithium chloride (LiCl). Importantly, two products are insoluble in the Li₂O-added melt and can be separated by a facile water leaching treatment. Notably, by incorporating an inert TiN anode, CO₂ emission during the electrolysis is eliminated by instead generating O₂, further contributing to carbon neutrality. With the low-temperature molten salt electrolyte ECR (LTMS-ECR) approach, a high cobalt recovery rate of 97.3% is achieved for LiCoO₂. Technoeconomic analyses project that the LTMS-ECR technology reduces energy consumption and CO₂ emission by ≈20% and is nearly ten times more profitable compared to conventional methods. The approach represents a revolutionary alternative for energy-effective, sustainable and economically viable recycling of spent LIBs.