Nickel-based layered double hydroxides (LDHs) having the composition Fe, Co) are isostructural with a-nickel hydroxide, stable to aging in alkali and deliver reversible discharge capacities corresponding to the a/g couple. The LDHs of Ni with Cr and Mn are also electrochemically active and deliver capacities of 500 (Ni-Cr), 400 (Ni-Mn, x ¼ 0:2) and 430 (Ni-Mn, x ¼ 0:1) mAh g À1 of Ni, respectively, while control electrodes of b bc (bc: badly crystalline)-nickel hydroxide deliver only 335 mAh g
À1. #