Lithium resurrection: Synergistic thermal-decomposition and electric-drive strategy enabling inactive lithium fully recycling

Abstract

Traditional pyrometallurgy and hydrometallurgy processes primarily focus on the recovery of valuable metals (Co, Ni, etc.) from spent lithium-ion batteries. However, these methods are not economical for recycling cheap LiFePO₄. Herein, a synergistic thermal-decomposition and electric-drive strategy is proposed to recover the whole spent LiFePO₄ electrode by in-situ recovering the inactive lithium (dead lithium and trapped interlayer lithium). Firstly, the organic components in the dense solid electrolyte interface (SEI) are effectively decomposed through thermal-decomposition processing, exposing the dead lithium encapsulated within the SEI and recovering the electron channels between the dead lithium and graphite. Leveraging the difference between the Gibbs free energy of the dead lithium and graphite as the driving force facilitates the dead lithium inserting into the anode. Then, fully utilizing the remaining discharge capacity of the spent LiFePO₄ cell, the inactive lithium is reinserted into LiFePO₄ lattice during the electric-drive process. Consequently, the reactivated lithium content increases by more than 16%, reaching a capacity of 134.2 mA h g⁻¹ compared to 115.2 mA h g⁻¹ from degraded LiFePO₄, allowing for effective participation in the subsequent cycling. This work provides new perspectives on highly profitable cycles with low energy and material consumption and a low carbon footprint.