By <<nickel-based hydroxide>> is meant a nickel hydroxide, a hydroxide mainly containing nickel, but also a nickel hydroxide containing at least one syncristallized hydroxide of an element selected from zinc (Zn), cadmium (Cd), magnesium (Mg) and aluminium (Al), and at least one syncristallized hydroxide of an element selected from cobalt (Co), manganese (Mn), aluminium (Al), yttrium (Y), calcium