Kill two birds with one stone: Self-nanoparticlization β-Cu2Se anode enabled by high efficiency and low-cost synthesis for wide-temperature sodium-ion batteries

The growing demand for electrochemical energy storage has accelerated the generation of battery waste, intensifying the need to recycle valuable components. However, transforming these discarded materials into high-rate electrode materials remains a significant challenge. Herein, we have proposed a unique strategy that converts waste copper foil into β-Cu 2 Se microparticles via a straightforward one-step solid-phase selenization process. When evaluated as an anode in a sodium half-cell, Cu 2 Se exhibits remarkable rate capability and cycling stability, achieving a capacity of 190 mAh g −1 within just 34 s, even at 20 A g −1 , and an impressive volumetric capacity of 1171 mAh cm −3 . Furthermore, a full sodium-ion battery incorporating the Cu 2 Se anode operates reliably across a wide temperature range (−20 to 40 ℃) in an ether-based electrolyte. This full battery also boasts exceptional rapid-charging capabilities, completing one cycle within only 5.3 min at −20 ℃. The distribution of relaxation times, in situ X-ray diffraction, and ex situ microscopy techniques reveal that the enhanced charge transfer and stabilized solid electrolyte interface film, which originated from the self-nanoparticlization, highly reversible structure, and dominant pseudocapacitive contribution, account for its outstanding capability. This work provides a novel strategy to tackle the challenge facing the regeneration of waste metals into high-value electrode materials. • The conversion of waste copper foil into β-Cu 2 Se microparticles is achieved via a one-step solid-phase selenization process. • The self-nanoparticlization behavior enhances charge transfer and stabilizes solid electrolyte interface. • The full battery exhibits impressive performance across a wide temperature range.