Ultrafast charging of two-dimensional polymer cathodes enabled by cross-flow structure design.

While ultrafast charging and discharging is highly desired for energy storage, the densely packed crystalline inorganic electrodes suffer from sluggish ion transport that limits this capability. Here we report two-dimensional vertical ladder polymer cathode materials that feature layered nanosheets with rich intralayer pores and structural defects alongside weak interlayer interactions. This structural design allows lithium ions to migrate vertically across the intrinsic pores and/or defects accompanied by horizontal intercalation, thus establishing a cross-flow pathway for lithium storage. Such an effective ion-transport method enables flash charging of an ultrahigh-power polymer cathode to ~70% state-of-charge within 30 s at a high current density. Even operated at -50 °C, the polymer cathode achieves 3-min charging to ~55% state-of-charge. Furthermore, we propose an organic-inorganic hybrid strategy that overall improves the electrode-level specific energy at high rates for meeting practical metrics. This work demonstrates the potential of organic electrodes for high-power output under extreme operational conditions.