a process for the regeneration of an at least partially spent zn - alkali slurry for use in metal - air batteries , including subjecting the slurry to at least the steps of separating the slurry into dissolved and undissolved phases ; electrolyzing the separated dissolved phase so that zn deposits on a cathode in removable form ; removing zn from the cathode and consolidating the zn into particles ; and combining the zn from step with the separated undissolved phase from step and an additional aqueous group ia metal hydroxide .