Impact of engineered dual-scale porosity for application-tailored battery electrodes

Abstract

The standard battery electrode contains disorganized and heterogeneous electrolyte-filled porosity, resulting in tortuous ion-transport pathways. When energy-dense batteries are quickly charged or discharged, insufficient ion-diffusion rates in the lithiating electrode result in capacity and energy loss due to underutilized active material and increased overpotential. To realize the full adoption of electric vehicles and enable electric vertical take-off and landing aircrafts, fast lithiation at high energy density is a principal challenge that must be overcome without introducing excessive porosity. Engineered multiscale porosity in the form of low-tortuosity and well-connected porous pathways both in the principle through-plane and the secondary in-plane ion-transport directions are a chemistry-agnostic approach to boost attainable capacity and energy at high lithiation rates. Here, we report such architected electrodes with tunable dual-scale porosity, existing as oriented micron-sized through-plane channels with unity tortuosity and well-connected sub-micron-sized in-plane pathways for efficient ion transport. When rationally coupled together, these transport channels enable 78% capacity retention at 4 C lithiation rates in electrodes with areal capacities over 4 mAh cm⁻², relevant total porosities between 0.3–0.6, and volumetric capacities up to 272 mAh cm⁻³.