Electrode design plays a critical role in defining the power and energy performance of Li-ion cells. Today’s state-of-art electrodes are manufactured by mixing active material particles, typically ranging from hundreds of nanometers to tens of micrometers, with binders, conductive aids, and solvents to form a slurry, then coating that slurry onto a metallic current collector foil as a wet film. After drying, the result is an electrode that consists of a single, homogeneous layer of material. In thick electrodes, the long, tortuous path that ions must travel into and out of the electrode results in sluggish lithium-ion flow. Thus, as electrode thickness is increased to achieve higher energy density, discharge power performance and charge rate suffer.

EnPower is developing advanced multilayer electrode architectures to address this underlying problem of lithium-ion mass transport. Instead of depositing a single wet film coating onto a foil substrate, EnPower simultaneously coats multiple slurries onto the foil, one on top of the other. The result is an electrode design that breaks away from the traditional energy-power tradeoff, enabling repeated fast charging and greater power performance for high energy density cells, or an increase in energy density given a specific power requirement. Multilayer design strategies can be applied to both the anode and cathode to improve specific performance parameters. Here, we look at the benefits of multilayer anodes, which are currently being sampled for customer validation. 

To measure the benefit of multilayer anode architectures, we compare their performance with “homogeneous baselines.” A homogeneous baseline is created by blending the formulations of each individual layer in a multilayer anode together to create a homogeneous slurry with the same net mass fractions of active materials, binders, and conductive aids as the multilayer electrode. This homogeneous slurry is then coated onto the metallic current collector foil as a single layer, typical of conventional Li-ion cells.