Structural, mechanical, and electronic properties of Ni-Co-based layered transition metal oxide LiNixCo1-xO2 for Li-ion batteries from first principles

The structural, mechanical, and electronic properties of Ni-Co-based layered transition oxide LiNixCo1-xO2 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9) (LNCO) have been investigated using the first-principles method. The results show that the effect of Ni/Co mixing on the structural property is slight. For the case of the mechanical property, the elastic constant, elastic modulus, such as Young's modulus (Y), Poisson's ratio (v), Pugh's ratio (B/G), and Cauchy pressure (C') of LNCO have been carefully analyzed based on the strain-energy method. The results demonstrate that the mechanical strength of LNCO materials is weaker than that of pure LiCoO2 (LCO) and LiNiO2 (LNO). However, the B/G ratio and Poisson's ratio of LNCO are greater than that of the pure LCO and LNO, which means that Ni/Co mixing can improve the ductility of pure LCO and LNO. In addition, Cauchy pressure and anisotropy are also discussed, and as cathode materials, LNCO still exhibits good electrical conductivity. Our results provide a feasible way to realize mechanical property modulation by Ni-Co-based layered transition metal oxides LCO. Furthermore, our study is also helpful to reveal the formation mechanism of intra-lattice microcracks in electrode materials.

Automated summary

The structural, mechanical, and electronic properties of Ni-Co-based layered transition oxide LiNixCo1-xO2 (x = 0.1-0.9) have been studied using the first-principles method. It is found that the effect of Ni/Co mixing on the structural property is slight. However, the mechanical strength of the materials is weaker than pure LiCoO2 and LiNiO2, while the ductility is improved. Cauchy pressure and anisotropy are also discussed, and the LNCO materials exhibit good electrical conductivity. This study provides insights into the modulation of mechanical properties and the formation mechanism of microcracks in electrode materials.