Engineering Freestanding Porous Carbon Electrodes by Self-Assembled Colloidal Liquid Crystalline Phase

Highly ordered pore channels can effectively improve mass transport in porous electrodes. However, due to the inherent trade-off between high porosity and structural regularity, achieving an ordered pore channel in practical highly porous electrode materials remains a challenge. To address this issue, we present a simple but highly efficient colloidal self-assembly (SA) route that is capable of constructing various ordered structures. By sedimentation-driven SA, we demonstrate that nematic liquid crystal (LC) carbon ring electrodes can be achieved. The electrodes are self-standing and binder-free. In particular, they have directional macropore channels aligned along the electrode direction and exhibit a high discharge specific capacity of up to 32785 mAh g^-1 in Li-O₂ batteries. This represents a 60% improvement compared to the disordered counterpart under the same conditions. As we demonstrated, the discharge specific capacities have a strong positive correlation with the degree of orientational order of carbon rings in the electrodes. The superior electrochemical performance can be attributed to the synergistic effect of directional Li-ion transport, more uniform junction distribution, and more uniform electric field distribution, which are brought about by the nematic LC structure. We expect to provide a new guideline for electrode structure design by using colloidal SA to regulate electrode structures.