| Summary: | Femtosecond ultrafast-laser micro-patterning was employed to prepare a three-dimensional (3D) structure for the tape-casting Ni-rich LiNi<sub>0.8</sub>Mn<sub>0.1</sub>Co<sub>0.1</sub>O<sub>2</sub> (NMC811) cathode. The influences of laser structuring on the electrochemical performance of NMC811 were investigated. The 3D-NMC811 cathode retained capacities of 77.8% at 2 C of initial capacity at 0.1 C, which was thrice that of 2D-NMC811 with an initial capacity of 27.8%. Cyclic voltammetry (CV) and impedance spectroscopy demonstrated that the 3D electrode improved the Li<sup>+</sup> ion transportation at the electrode–electrolyte interface, resulting in a higher rate capability. The diffusivity coefficient <i>D</i><sub>Li+</sub>, calculated by both CV and electrochemical impedance spectroscopy, revealed that 3D-NMC811 delivered faster Li<sup>+</sup> ion transportation with higher <i>D</i><sub>Li+</sub> than that of 2D-NMC811. The laser ablation of the active material also led to a lower charge–transfer resistance, which represented lower polarization and improved Li<sup>+</sup> ion diffusivity.
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