High Energy X-Ray Used to Investigate the Synthesis of Full Concentration Gradient Cathode

Nickel-rich lithium transition metal oxides can deliver a high specific capacity during cycling, but there is a concern about the highly reaction between the cathode and the non-aqueous electrolytes. To maintain high specific capacity and improve cycling performance , we have employed solid state reaction to synthesize a full concentration gradient (FCG) cathode, which has a nominal composition of LiNi_0.6Mn_0.2Co_0.2. It is  designed to provide a nickel-rich core to deliver high capacity and a manganese-rich outer layer to provide enhanced stability and cycle life. The solid-state reaction to form a high performance nickel-rich cathode material is a complicated multiple-step reaction.  Therefore, in situ high-energy X-ray diffraction was utilized to study the structural evolution during the solid-state synthesis of FCG cathode. We found that both the pre-heating step and the sintering temperature were critical in controlling phase separation of the transition metal oxides and minimizing the content of Li₂CO₃ and NiO, both of which deteriorate the electrochemical performance of the final material. The insights revealed in this talk can also be utilized for the design of other nickel-rich high energy-density cathode materials.