Reaction-passivation-driven delamination of spent LiFePO4 cathodes and their upgrading to highly efficient catalysts for hydrogen evolution

Abstract

2-Hydroxyphosphonic acid (HPAA) was demonstrated to delaminate spent LiFePO₄ cathodes from Al foil via a reaction-passivation mechanism, resulting in ultra-high-purity products and facilitating subsequent upgrading. As a proof of concept, Fe_xP catalysts prepared from lithium-extracted FePO₄ slag deliver a hydrogen evolution current density of 10 mA cm⁻² at an overpotential of only 88 mV.