The present disclosure relates to an electrochemically active lithium-rich layered oxide having the general formula Li.sub.[(1.33-0.67x-y)Mn.sub.(0.67-0.5z-0.33x)Ni.sub.(x-0.5z+2y)M.sub.(z-- y)O.sub.2, wherein M is cobalt (Co), chromium (Cr), or any combinations thereof, wherein, with respect to the amount of Li, 1<(1.33-0.67x-y)<1.2, wherein, with respect to the amount of Mn, 0.5<(0.67-0.5z-0.33x)<0.6, wherein, with respect to the amount of Ni, 0.2<(x-0.5z+2y)<0.5, and wherein, with respect to the amount of M, 0<(z-y)<0.13. The present disclosure further relates to cathodes and rechargeable batteries containing such a lithium-rich layered oxide.
STATEMENT OF GOVERNMENT INTEREST
 The present invention was developed using funds from the Department of Energy under Grant No. RFP-DY-2011-04. The United States Government has rights to this invention.