Complementarydual-dopingofLiNi0.8Co0.1Mn0.1O2cathodeenhancesion-diffusionandstabilityforLi-ionbatteries

The Ni-richLiNi0.8Co0.1Mn0.1O2（NCM811） layered cathodes endow Li-ion batteries （LIBs） with high energy density.However,they usually suffer from limited ion-diffusion and structural instability during cycling.Although doping strategy can effectively alleviate these issues,the coupling effects of multi-element doping and the corresponding performance enhancement mechanism have been yet unclear.Here,we report a Zr/Ti dual-doped NCM811 cathode material （ZT-NCM811）,in which Zr-ion is doped into both transition metal （TM） layers and lithium layers and Ti-ion is only distributed in TM layers.The dual-doping can effectively enhance crystal structure stability via inhibiting the lattice collapse along c-axis and decreasing the Li/Ni disorder.Meantime,the lattice oxygen escape is also greatly reduced due to the presence of stronger Zr-O and Ti-O bonds,further mitigating the crystal surface parasitic reactions with electrolyte.The resultant ZT-NCM811 exhibits high specific capacity of 124 m Ah/g at even 10 C,much higher than undoped and single-doped NCM811,and a retention of 98.8%at 1 C after 100 cycles.The assembled ZT-NCM811/graphite full cell also delivers superior battery performances and durability.