The Forming Process in Nickel Positive Electrodes

A detailed study has been made of the phases produced and their geometric distribution during formation of Edison‐type tubular positive nickel electrodes. The initial charging in lithiated electrolytes converts the to a beta phase having a solid solution range for di‐ and tetravalent nickel. The beta crystalline structure is related to . This phase can be further oxidized to alpha phase, a tetravalent nickelate having appreciable trivalent nickel solid solubility. Alpha phase is most readily formed during oxidation in concentrated or electrolytes, but does not form in electrolytes. The addition of to the battery electrolyte contributes to alpha phase discharge and limits alpha phase reformation. The contribution of alpha phase to electrochemical capacity is limited by a low effective exchange current as compared to the beta phase.