This invention relates generally to electrode materials, electrochemical cells employing such materials, and methods of synthesizing such materials. The electrode materials have a crystal structure with a high ratio of Li to metal M, which is found to improve capacity by enabling the transfer of a greater amount of lithium per metal, and which is also found to improve stability by retaining a sufficient amount of lithium after charging. Furthermore, synthesis techniques are presented which result in improved charge and discharge capacities and reduced particle sizes of the electrode materials.