Exploring the Synergistic Effects of Dual-Layer Electrodes for High Power Li-Ion Batteries

The electrification of the transport sector has created an increasing demand for lithium-ion batteries that can provide high power intermittently while maintaining a high energy density. Given the difficulty in designing a single redox material with both high power and energy density, electrodes based on composites of several electroactive materials optimized for power or capacity are being studied extensively. Among others, fast-charging LiFePO4 and high energy Li(NixMnyCoz)O-2 are commonly employed in industrial cell manufacturing. This study focuses on comparing different approaches to combining these two active materials into a single electrode. These arrangements were compared using standard electrochemical (dis)charge procedures and using synchrotron X-ray fluorescence to identify variations in solution concentration gradient formation. The electrochemical performance of the layered electrodes with the high-power material on top is found to be enhanced relative to its blended electrode counterpart when (dis)charged at the same specific currents. These findings highlight dual-layer lithium-ion batteries as an inexpensive way of increasing energy and power density of lithium-ion batteries as well as a model system to study and exploit the synergistic effects of blended electrodes.