Synthesis and Characterization of Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 with the Microscale Core−Shell Structure as the Positive Electrode Material for Lithium Batteries

The high capacity of Ni-rich Li[Ni1-xMx]O2 (M = Co, Mn) is very attractive, if the structural instability and thermal properties are improved. Li[Ni0.5Mn0.5]O2 has good thermal and structural stabilities, but it has a low capacity and rate capability relative to the Ni-rich Li[Ni1-xMx]O2. We synthesized a spherical core−shell structure with a high capacity (from the Li[Ni0.8Co0.1Mn0.1]O2 core) and a good thermal stability (from the Li[Ni0.5Mn0.5]O2 shell). This report is about the microscale spherical core−shell structure, that is, Li[Ni0.8Co0.1Mn0.1]O2 as the core and a Li[Ni0.5Mn0.5]O2 as the shell. A high capacity was delivered from the Li[Ni0.8Co0.1Mn0.1]O2 core, and a high thermal stability was achieved by the Li[Ni0.5Mn0.5]O2 shell. The core−shell structured Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2/carbon cell had a superior cyclability and thermal stability relative to the Li[Ni0.8Co0.1Mn0.1]O2 at the 1 C rate for 500 cycles. The core−shell structured Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 as a new positive electrode material is a significant breakthrough in the development of high-capacity lithium batteries.