Critical challenges such as safety and cyclability concerns resulting from the uncontrollable dendritic lithium (Li) growth, especially during the fast charging/discharging process, have seriously hampered the commercialization of Li metal batteries (LMBs). Here, a novel array-patterned LiFePO4 (LFP) cathode prepared via a simple, scalable calendaring method is developed to enable highly stable Li metal anodes with patterned ditches and bulges during the cell assembling process. Both the structured electrodes provide a remarkably increased electroactive surface area to lower the current density locally, facilitating Li-ion transport kinetics and homogeneous Li plating/stripping. Due to the long-term internal pressure in the cell, the structured LFP and Li electrodes can maintain their original structure during sustained cycling. Such distinctive electrode architectures and cell design synergistically enable excellent rate capability with a discharge capacity of up to 128 mA h g-1 at a high current density of 9 mA cm-2 and impressive cycling stability, with 89.6% capacity retention after 300 cycles at 1.5 mA cm-2. Moreover, ultrasonic transmission mapping is carried out and demonstrates no gas behavior in operating modified Li||LFP pouch cells over prolonged cycling. This simple fabrication method can potentially be applied to many other active materials to enable practical LMBs with high performance.
Keywords: cell design; electroactive surface area; electrochemical performance; lithium metal batteries; structured electrodes.