This study reports on a preparation of novel Ni-rich cathode material with isolated porous layer and its application into cathode in lithium ion batteries extending cut-off potential into 4.5 V. Using intermittent addition of Al salt during co-precipitation of Ni_xCo_1-x(OH)₂ (0 < x < 1), the isolated porous layer is easily formed inside the final active material particles maintaining overall mechanical integrity and their spherical shape without the change of external particle morphology. Even under severe cut-off potential of 4.5 V, volume expansion/contraction by anisotropic mechanical stress from hexagonal 2 to 3 (H2 → H3) phase transition is greatly reduced by hindering inner particle crack propagation into the external area at particle surface. Due to this phenomena, 227 mAh/g initial capacity at 0.1C was obtained upon 86 mol% of Ni content, with 75 % cathode capacity retention after 100 cycles under 1C, which is highest …​