Improved electrochemical performance and thermal stability of Li-rich material Li1.2(Ni0.25Co0.25Mn0.5)0.8O2 through a novel core-shelled structure design

Abstract To improve the electrochemical performances and thermal stability of Ni, Co-containing Li-rich materials, Li 1.2 (Ni 0.25 Co 0.25 Mn 0.5 ) 0.8 O 2 is redesigned into Li 1.2 [(Co 0.5 Mn 0.5 ) 1/2 (Ni 0.5 Mn 0.5 ) 1/2 ] 0.8 O 2 with a novel core-shelled structure for the first time. Subsequently, this core-shelled material is prepared successfully via co-precipitation and solid state method. The core-shelled structure of Li 1.2 [(Co 0.5 Mn 0.5 ) 1/2 (Ni 0.5 Mn 0.5 ) 1/2 ] 0.8 O 2 is certified by Energy Disperse X-ray Spectrum (EDS) on the cross-section of the single particle. Different from the conventional core-shelled structure design of Li-rich materials, in which Mn-rich materials act as core and Ni-rich materials act as shell, the novel core-shelled structure of Li 1.2 [(Co 0.5 Mn 0.5 ) 1/2 (Ni 0.5 Mn 0.5 ) 1/2 ] 0.8 O 2 incorporates the advantages of Co-rich core and Ni-rich shell. Subsequently, improved cyclability, rate capability and thermal stability are obtained in Li 1.2 [(Co 0.5 Mn 0.5 ) 1/2 (Ni 0.5 Mn 0.5 ) 1/2 ] 0.8 O 2 .