The invention relates to electrodes comprising doped nickelate-containing compositions comprising a first component-type comprising one or more components with an O3 structure of the general formula: AaM1vM2wM3xM4yM5zO2 wherein A comprises one or more alkali metal selected from sodium, lithium and potassium M1 is nickel in oxidation state 2+, M2 comprises one or more metals in oxidation state 4+, M3 comprises one or more metals in oxidation state 2+, M4 comprises one or more metals in oxidation state 4+, and M5 comprises one or more metals in oxidation state 3+ wherein 0.85≤a≤1; 0 0; x≥0; z≥0; and wherein a, v, w, x, y and z are chosen to maintain electroneutrality; together with one or more component-types selected from a second component-type comprising one or more components with a P2 structure of the general formula: A′a′ 0; x′≥0, preferably x′>0; z′>0; and wherein a′, v′, w′, x′, y′ and z′ are chosen to maintain electroneutrality; and a third component-type comprising one or more components with a P3 structure of the general formula: A″a″M1″v″M2″w″M3″x″M4″y″M5″z″O2 wherein A″ comprises one or more alkali metals selected from sodium, lithium and potassium; M1″ is nickel in oxidation state 2+, M2″ comprises one or more metals in oxidation state 4+, M3″ comprises one or more metals in oxidation state 2−, M4″ comprises one or more metals in oxidation state 4+, and M5″ comprises one or more metals in oxidation state 3+ wherein 0.4≤a″ 0; x″≥0; z″≥0; and wherein a″, v″, w″, x″, y″ and z″ are chosen to maintain electroneutrality.