Na doping into Li-rich layered single crystal nanoparticles for high-performance lithium-ion batteries cathodes

Lithium-rich layered manganese-based cathodes (LRLMOs) with first-class energy density (∼1000 W h kg^-1) have attracted wide attention. Nevertheless, the weak cycle stability and bad rate capability obstruct their large-scale commercial application. Here, single crystal Li_1.2-xNa_xNi_0.2Mn_0.6O₂(x = 0, 0.05, 0.1, 0.15) nanoparticles are designed and successfully synthesized due to the single crystal structure with smaller internal stress and larger ionic radius of Na. The synergistic advantages of single crystal structure and Na doping are authenticated as cathodes for Li ion batteries (LIBs), which can consolidate the crystallographic structure and be benefit for migration of lithium ion. Among all the Na doping single crystals, Li_1.1Na_0.1Ni_0.2Mn_0.6O₂cathode possesses supreme cycling life and discharge capacity at large current density. To be more specific, it exhibits a discharge capacity of 264.2 mAh g^-1after 50 charge and discharge cycles, higher than that of undoped material (214.9 mAh g^-1). The discharge capacity of Li_1.1Na_0.1Ni_0.2Mn_0.6O₂cathode at 10 C (1 C = 200 mA g^-1) is enhanced to 160.4 mAh g^-1(106.7 mAh g^-1forx = 0 sample). The creative strategy of Na doping single crystal LRLMOs might furnish an idea to create cathode materials with high energy and power density for next generation LIBs.