Summary
Flexible lithium-ion batteries need electrodes that bend without cracking and ideally work without a metal current collector or polymer binder. This study electrospins carbon/germanium-dioxide (C/GeO₂) fibres and heat-treats them (stabilisation plus carbonisation) into self-supporting, paper-like membranes that serve directly as binder- and collector-free anodes. Carbonisation is deliberately kept at a low 550 °C to preserve a high nitrogen content in the carbon fibre network, which benefits lithium storage. Across a range of germanium loadings (2.50–4.25 wt%), the process yields α-quartz GeO₂ nanoparticles encapsulated within heavily N-doped (10–16 at%) carbon fibres; both the oxide particle size and the fibre diameter grow with higher germanium content. The result is a lightweight, flexible fibrous electrode combining a high-capacity GeO₂ active phase with a conductive, nitrogen-rich carbon scaffold.