Fast-Charging Lithium-Ion Batteries Enabled by Magnetically Aligned Electrodes

With the increasing popularity of electric transportation over the past several years, fast-charging lithium-ion batteries are highly demanded for shortening electric vehicles' charging time. Extensive efforts have been made on material development and electrode engineering; however, few of them are scalable and cost-effective enough to be potentially incorporated into the current battery production. Here, we propose a facile magnetic templating method for preparing LiFePO4 (LFP) cathodes with vertically aligned graphene sheets to realize fast-charging properties at a practical loading of 20 mg cm-2. Graphene sheets decorated with Fe3O4 nanoparticles can be responsive to an external magnetic field and can maintain their vertical alignment during the electrode fabrication process. The vertically aligned graphene provides the magnetized LFP electrodes (m-LFP) with simultaneously improved electron and lithium-ion transport properties, achieving 110 and 76 mA h g-1 at 3C and 4C, respectively. Furthermore, magnetized Fe3O4 (m-Fe3O4) anodes were also prepared via the magnetic templating method to vertically align the Fe3O4 nanosheets inside, which outperforms the conventional graphite anodes at a high rate of 3C. Finally, by pairing the magnetized LFP cathode and Fe3O4 anode, we demonstrate the simultaneous fast-charging properties and good cycling stability in the m-LFP||Fe3O4 full cells. This study not only provides an effective methodology for achieving vertically aligned structures which can potentially be incorporated into industrial manufacturing but also brings insightful considerations for designing scalable fast-charging energy storage systems.