ANALYSIS OF PH TITRATION DATA IN A LAMBDA-MNO2 + LIOH SYSTEM ON THE BASIS OF REDOX MECHANISM

Spinel-type manganese oxide, ʎ-MnO2,1 shows a remarkably high selectivity for lithium ions in the aqueous phase in the range above pH 2.5.2,3 A pH titration study could be described in terms of the H+/Li+ ion-exchange mechanism for the Li+ insertion in ʎ-MnO2.4 However, chemical and X-ray analyses have shown that the Li+ insertion proceeds topotactically, involving a reduction of Mn(IV) to Mn(III) as well as an evolution of oxygen gas.5,6 The major reaction can be represented not by an ion exchange but by a new type of redox mechanism. © 1990, American Chemical Society. All rights reserved.