High tap density microparticles of selenium-doped germanium as a high efficiency, stable cycling lithium-ion battery anode material

Slurry cast electrodes with μm-sized Ge0.9Se0.1 particles cycle stably at ∼800 mA h g⁻¹ with ∼99.9% efficiency for 900 1C-rate cycles while electrodes with μm-size pure Ge particles lose 1/3rd of their capacity after five C/5 cycles. The difference is attributed to an inactive glassy Li–Se–Ge phase.