Ni-rich cathode nanomaterials with enhanced exposed Li-ion diffusion pathways for Li-ion batteries


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As one of the Li-ion batteries‘ most promising cathode materials, Ni-rich layered transition-metal-mixed oxide LiNixCoyMn1-x-yO2 (NCM, x>0.5) has drawn intense attention in the search for high energy density, low cost, and reduced Co content materials. However, Ni-rich NCM cathodes are still suffering from several drawbacks. Cation disorder and volume expansion during Li-ion (de)intercalation are mainly responsible for the inadequate storage capacity and moderate cycling stability of Ni-rich NCM cathodes. Therefore, further improvement and optimization are necessary to realize their full potential as the next-generation cathode in Li-ion batteries. Several strategies have been employed to overcome these problems, such as cation doping, surface coating, and structure modification. However, cation doping and surface coating are always at the expense of energy density as the introduced compounds are typically electrochemical inactive. On the other hand, architecture control is crucial for promoting Li-ion transport inside the electrode particles and this can improve the electrode performance without compromising the energy density of NCM cathode materials.
Herein, we designed and successfully synthesized Ni-rich LiNi0.6Co0.2Mn0.2O2 nanomaterials with a unique nanobrick morphology. This structure presented a large exposed ratio of high energy (010) planes, where two-dimension Li-ion diffusion pathways are located in the NCM materials. A facile hydrothermal method combined with surfactant assistance was used during the synthesis for controlling particle growth. TEM measurements show that the lateral surfaces of the particles are composed of (010) planes. Highly exposed (010) planes in the structure accordingly resulted in a favorable Li-ion diffusion coefficient. Consequently, the electrochemical tests show superior cyclability, along with fast rate capability, indicating that these cathode materials might be interesting to be applied in Li-ion batteries.

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