Anisotropic Atomic Mobilities of Layer-Structured O3 Li_xCoO₂ Cathodes and Their Applications in Optimization of Battery Performance

Abstract

In this paper, the concept of anisotropic atomic mobility is first developed in the framework of CALPHAD approach, and atomic mobility descriptions of Li ions in the layered O3 Li x CoO 2 are then assessed based on the experimental self/ tracer diffusion coefficients available in the literature. After that, the chemical diffusion coefficients as a function of compositions and crystal orientations are model predicted and utilized to validate the available experimental/theoretical data with large discrepancies. The result indicates that the ratio of D Li self-ab /D Li self-c should be on the order of 100. Moreover, the analytical modeling of phase transition from O3 to O3′ phase under different charging currents and crystal anisotropies is performed, from which the quantitative atomic mobility−anisotropy−charging current relationships are established. Finally, the battery performance during the charging process is optimized in terms of kinetic requirements, and the optimal charging current (7.5−12.5 mA) and anisotropy orientation angle (close to 0) range corresponding to the preferred battery performance is designed. It is anticipated that this work may serve as a general guide to optimize the battery performance of cathodes during the charging process in Li battery in terms of diffusion kinetics.

Influence of Active Material Loading on Electrochemical Reactions in Composite Solid-State Battery Electrodes Revealed by Operando 3D CT-XANES Imaging

“…This is partly because LCO has a relatively high Young’s modulus and does not easily plastically deform, and thus the contact areas between the LCO particles tend to be small (left panel in Figure b). Furthermore, the Li ion diffusivity in LCO largely depends on the crystallographic orientation. , While Li ions easily move along the CoO 2 layers, the Li ion diffusion perpendicular to the CoO 2 layers is considerably impeded due to the presence of CoO 2 layers. Therefore, the Li ion transport can also be hindered at the interfaces where the LCO particles with different crystallographic orientation are in contact (right panel in Figure b) .…”

Bayesian Parameterization of Continuum Battery Models from Featurized Electrochemical Measurements Considering Noise**

“…The functional form of the exchange‐current density $${i_{se,k,0}^ * \left( {c_e^ *, c_{s,k}^ * } \right)}$$ is an active topic of research [70–73] . Likewise, the active material diffusivities $${D_{s,k}^ * \left( {c_{s,k}^ * } \right)}$$ depend on electrode SOC [74] . Hence, there are three parameters of interest that do not depend on SOC, namely $${t_ + }$$ , $${\beta _p }$$ , and $${\beta _n }$$ , and four that do depend on SOC, namely $${i_{se,p,0}^ * }$$ , $${i_{se,n,0}^ * }$$ , $${D_{s,p}^ * }$$ and $${D_{s,n}^ * }$$ .…”

“…[70][71][72][73] Likewise, the active material diffusivities D � s;k c � s;k � � depend on electrode SOC. [74] Hence, there are Table 3. The missing battery parameters and how we procure them.…”

Crystallographically Textured Electrodes for Rechargeable Batteries: Symmetry, Fabrication, and Characterization

“…While we used graphite as an example to illustrate the concept, it is generally applicable to all materials of a 2D, layered nature, for example, transition metal dichalcogenides (such as MoS 2 ), black phosphorus, layered transition metal oxides (e.g., LiCoO 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , Li-rich layered oxides), − MXenes; materials of a 1D, tunneled nature, for example, Wadsley–Roth crystallographic shear structures (such as Nb 2 O 5 ·8WO 3 ) , and channeled transition metal oxides (such as α-MnO 2 ); , and materials that are not generally considered “2D”/“1D”, for example, LiFePO 4 , − LiMn 2 O 4 , and Li 2 FeSiO 4 , but still show nontrivial transport anisotropy. These together constitute a large portion of electrode chemistry of contemporary interest.…”