A structurally and compositionally disordered electrochemically active alloy material is provided with excellent capacity and cycle life, as well as superior high-rate dischargeability. The alloy employs a disordered A2B4+x(AB5) structure, wherein x is a number between 1 and 4. This crystal structure combined with a tailored amount of electrochemically active AB5 secondary phase material produces superior electrochemical properties.