US Patent 11424449 Stable cathode materials

Provided are electrochemically active particles suitable for use as an active material in a cathode of a lithium ion electrochemical cell that include: a plurality of crystallites comprising a first composition comprising lithium, nickel, and oxygen; and a grain boundary between adjacent crystallites of the plurality of crystallites and comprising a second composition comprising lithium, nickel, and oxygen; wherein the grain boundary has a higher electrochemical affinity for lithium than the crystallites. The higher electrochemical affinity for Li leads to increased Li retention in the grain boundaries during or at charge relative to the bulk crystallites and stabilizes the structure of the grain boundaries and crystallites for improved cycling stability with no appreciable loss in capacity.