Introduction -- Experimental and Theoretical Considerations -- Optimization of the Synthesis of Combinatorial Samples -- Combinatorial Studies in the Li-Co-Mn-O System -- Combinatorial Studies of the Spinel and Rocksalt Re­gions in the Li-Mn-Ni-O System -- Combinatorial Studies of Compositions Containing Lay­ered Phases in the Li-Mn-Ni-O System -- Investigations of Bulk Li-Mn-Ni-O Samples to Confirm the Combinatorial Studies -- Layered Materials with Metal Site Vacancies -- Materials Near the Layered Boundary -- Conclusions and Future Works.