Mat. Res. Bull., Vol. 21, pp. 609-619, 1986. Printed in the USA. 0025-5408/86 $3.00 + .00 Copyright (c) 1986 Pergamon Journals Ltd. LITHIUM INSERTION REACTIONS OF SPINELS: EFFECT OF THE DISTRIBUTION AND REDUCIBILITY OF CATIONS IN SELECTED MANGANITE AND ZINC SPINELS C.J. Chen, M. Greenblatt t Department of Chemistry Rutgers, The State University of New Jersey New Brunswick, NJ 08903 and J.V. Waszczak AT&T Bell Laboratories, Murray Hill, NJ 07974 (Received March 3, 1986; Communicated by A. Wold) ABSTRACT Lithium insertion reactions b~ n-BuLl and electrochemical techniques of various MMn204, M=Zn 2+, Ni z+, Cd 2+ compounds demonstrate that upon lithium insertion Mn 3+ is reduced to Mn 2+ and the cooperative Jahn-Teller effect present in the tetragonal host spinels is absent in their lithiated analoques as indicated by the tetragonal to cubic structural transformation that occurs. These studies and similar lithium insertion reactions of ZnB204, B=Co 3+, Cr 3+, [Fe3+Mn3+]0. 5 show that an important factor in the extent and kinetics of lithium insertion reactions in splnels is the ease of the reducibility of the transition metal cations. MATERIALS INDEX: lithium insertion, spinels, manganese, zinc. Introduction Recent studies of topotactic lithium insertion/extraction, oxidatlon/reductlon reactions in a variety of spinel phases including Fe304 (I), Mn304 (2), Co304 (3), LiMn204 (2,4-7), LiTi204 (8-10), LiV204 (8,11) and various other compositions (12,13) have demonstrated fast Li + ion diffusion. 609