Sodium ion batteries (SIBs) have drawn considerable attentions as a promising alternative to lithium-ion batteries (LIBs) for large-scale energy storage. However, the lower specific capacities and more sluggish insertion/extraction kinetics related to the greater atomic mass and larger ionic radius make it a severe challenge to develop high-energy and high-power SIBs.

Electrode architecture design with high mass loading of active materials is considered as a more straightforward strategy to achieve high energy. It can increase the percentage of active materials and consequently energy density at device/cell levels.

Recently, a research group led by Prof. LI Xianfeng and Dr. ZHENG Qiong from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) designed and optimized a low-tortuosity and high-areal-capacity cathode for high rate and ultra-stable SIBs via non-solvent induced phase separation derived method.

The results were published in Advanced Energy Materials on March 18.

Schematics illustrating the ion transport pathways in diverse electrodes (Image by LV Zhiqiang and YUE Meng)

The researchers reported a low-tortuosity, finger-like composite electrode with ultra-high mass loading based on nonsolvent-induced phase separation method, which could offer well-pleasing electron/ion transport pathway and relatively low battery resistance.

Benefiting from the structural advantages, they achieved the as-prepared electrode with ultra-high mass loading (60 mg/cm²) and areal capacity (4.0 mAh/cm²). Even at a high rate of 10 C, the areal capacity remains 1.0 mAh/cm².

Comprehensive understanding on the effects of low-tortuosity architecture to the spatial and temporal distribution of the multi-physical field parameters was elucidated by the finite element method simultaneously. A homogeneous Na+ distribution, gentle and uniform local current density and polarization inside the as-prepared electrode were illustrated.

Combining numerical simulations and experiments, it revealed that the low-tortuosity architecture could contribute to an impressive ion transport capability and consequently significant improvements in electrochemical performance.

This study exhibits a prospective solution for the design & optimization of the low-tortuosity electrodes with ultra-high mass loading, which opens a new door for developing advanced SIBs with high energy/power density.

This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China, Youth Innovation Promotion Association of CAS, and the Dalian National Laboratory Cooperation Fund, CAS. (Text by LV Zhiqiang and YUE Meng)