A series of heterogeneous Se-doped cobalt-free high nickel layered cathodes LiNi_0.847Mn_0.092Al_0.061O₂ are synthesized using the high-temperature solid-phase method to address the issues of rapid capacity decay, poor stability, and structural phase transition in cobalt-free high nickel materials. The results show that Se doping can effectively inhibit the formation and diffusion of structural phase transition and micro-cracks. Among them, the doping amount of 1% LiNi_0.837Mn_0.092Al_0.061Se_0.01O₂ low degree of positive electrode material of lithium nickel are mixed, with better crystallinity and lamellar structure. At a high-voltage of 4.5 V, the specific discharge capacity of LiNi_0.837Mn_0.092Al_0.061Se_0.01O₂ is as high as 207.61 mAh·g⁻¹, and the capacity retention rate increased from 69.37% without doping to 85.45% after 100 cycles at 1C.