Abstract: In one embodiment, the invention provides a novel active material which is a lithium-rich, manganese oxide active material in the form of a single phase tetragonal crystal structured Li.sub.2 Mn.sub.2 O.sub.4 compound having lattice parameters a=b=5.665 .ANG..+-.0.003 .ANG., and c=9.265 .ANG..+-.0.003 .ANG.. A unique characteristic of the compound is that when lithium ions are deintercalated (extracted) from the Li.sub.2 Mn.sub.2 O.sub.4 at first and second voltage plateaus, the crystal structure is transformed to a cubic structure characterized by lattice parameters a=b=c=8.235 .ANG..+-.0.004 .ANG.. On subsequent charge and discharge of the battery, corresponding to subsequent extraction and reinsertion of lithium into the electrode material at the second voltage plateau, the cubic structure is maintained.

Abstract: A solid secondary lithium electrochemical cell comprises a physical mixture of Li.sub.x n.sub.2 O.sub.4 (spinel) (0<x.ltoreq.2) and at least one second compound selected from LiFeO.sub.3, .alpha.LiFe.sub.5 O.sub.8, .beta.-LiFe.sub.5 O.sub.8, LiFe.sub.3 O.sub.4, LiFe.sub.2 O.sub.3, Li.sub.1+w, Fe.sub.5 O.sub.8 (0<w<4), Li.sub.y V.sub.2 O.sub.5 (0<y<2), and Li.sub.z FeV.sub.2 O.sub.5 (0<z<2). The cell is particularly suitable for use with anodes carbon materials.

Abstract: The invention provides an electrochemical cell which is at least partially charged and which comprises a first electrode having an active material in particle form consisting essentially of at least partially lithiated graphite. The lithiated graphite particles are prepared by chemically or electrochemically inserting lithium ions into the particles prior to assembly of the cell. A second electrode which is a counter electrode to the first electrode has an active material consisting essentially of vanadium oxide.