Improved Cycling Stability of Li[Ni0.90Co0.05Mn0.05]O2 Through Microstructure Modification by Boron Doping for Li-Ion Batteries

Abstract

Boron-doped Li[Ni0.90Co0.05Mn0.05]O2 cathodes are synthesized by adding B2O3 during the lithiation of the hydroxide precursor. Density functional theory confirms that boron doping at a level as low as 1 mol% alters the surface energies to produce a highly textured microstructure that can partially relieve the intrinsic internal strain generated during the deep charging of Li[Ni0.90Co0.05Mn0.05]O2. The 1 mol% B-Li[Ni0.90Co0.05Mn0.05]O2 cathode thus delivers a discharge capacity of 237 mAh g−1 at 4.3 V, with an outstanding capacity retention of 91% after 100 cycles at 55 °C, which is 15% higher than that of the undoped Li[Ni0.90Co0.05Mn0.05]O2 cathode. This proposed synthesis strategy demonstrates that an optimal microstructure exists for extending the cycle life of Ni-rich Li[Ni1-x-yCoxMny]O2 cathodes that have an inadequate cycling stability in electric vehicle applications and indicates that an optimal microstructure can be achieved through surface energy modification.