Nature Materials, Published online: 22 July 2025; doi:10.1038/s41563-025-02293-9Cathode materials for lithium-ion batteries typically possess octahedral coordination, which may exclude other possible solutions to degradation during deep cycling. A series of tetrahedral-framework-based amorphous Li–V–O–F materials are investigated, and shown to demonstrate O–O formal redox at 4.1 V.