An efficient thick electrode design with artificial porous structure and gradient particle arrangement for lithium-ion batteries

Thick electrode, with its feasibility and cost-effectiveness, has attracted significant attention as a promising approach to maximize the energy density of lithium-ion batteries (LIBs). Through raising the mass loading of active materials without altering the fundamental chemical attributes, thick electrodes can boost the energy density of the batteries effectively. Nevertheless, as the thickness of the electrode increases, the ionic conductivity of the electrode decreases, leading to abominable polarization in the thickness direction, which severely hampers the practical application of a thick electrode. This work proposes a novel porous gradient design of high-performance thick electrodes for LIBs. By constructing a porous structure that serves as a fast transport pathway for lithium (Li) ions, the ion transport kinetics within thick electrodes are significantly enhanced. Meanwhile, a particle size gradient design is incorporated to further mitigate polarization effects within the electrode, leading to substantial improvements in reaction homogeneity and material utilization. Employing this strategy, we have fabricated a porous gradient nanocellulose-carbon-nanotube based thick electrode, which exhibits an impressive capacity retention of 86.7% at a high mass loading of LiCoO2 (LCO) active material (20 mg cm⁻²) and a high current density of 5 mA cm⁻².