The tortuosity represents the degree of curvature of the transmission path of porous electrodes, and is another important parameter related to transmission characteristics in addition to porosity.

The effective ion conductivity is inversely proportional to the tortuosity of the electrode, which means that the lower the tortuosity, the better the conductivity. Therefore, in order to improve the permeability of electrolyte and the migration rate of ions, the design of electrode structures with low tortuosity has become a key principle in porous electrode design. 

For example, as the compaction density increases, the contact between graphite particles and conductive agent particles becomes denser, the performance of absorbing electrolyte deteriorates, the electrolyte is difficult to infiltrate, making the migration of lithium ions more difficult, increasing the ion transport impedance, and resulting in an increase in the tortuosity of the electrode. In addition, the tortuosity and porosity, electrode formulation, porosity, and morphology of the main material are all related.

1. Excessive compaction leads to an increase in tortuosity within a certain range
2. The tortuosity of electrodes with a high proportion of main materials changes less with the decrease of porosity.  
3. The overall tortuosity of electrodes composed of sheet-like main materials is greater than that of spherical main materials.                        
4. Different binders have different effects on the tortuosity, for example, sodium alginate binder has a smaller tortuosity on graphite electrodes than CMC/SBR.

5. Adhesives with a larger surface area have relatively lower electrode tortuosity.
6. The higher the porosity, the smaller the curvature within a certain range.
By optimizing electrode formulation, pore structure, fractal morphology, preparation techniques, and other methods to reduce electrode tortuosity, the ion transport rate in porous electrodes can be improved.