Capacitance loss with the increase of mass loading represents an outstanding challenge for supercapacitors. Here we demonstrate for the first time a mm-thick, 3D printed graphene aerogel structure that can support pseudocapacitive MnO 2 to hundreds of mg/cm 2 without sacrificing its gravimetric and volumetric performance. The electrode simultaneously achieves high gravimetric, areal, and volumetric capacitances, which is impossible for conventional bulk electrodes. Most importantly, these findings validate the new concept of ''printing'' practically feasible pseudocapacitor electrodes and devices.

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The performance of pseudocapacitive electrodes at fast charging rates are typically limited by the slow kinetics of Faradaic reactions and sluggish ion diffusion in the bulk structure. This is particularly problematic for thick electrodes and electrodes highly loaded with active materials. Here, a surface‐functionalized 3D‐printed graphene aerogel (SF‐3D GA) is presented that achieves not only a benchmark areal capacitance of 2195 mF cm−2 at a high current density of 100 mA cm−2 but also an ultrahigh intrinsic capacitance of 309.1 µF cm−2 even at a high mass loading of 12.8 mg cm−2. Importantly, the kinetic analysis reveals that the capacitance of SF‐3D GA electrode is primarily (93.3%) contributed from fast kinetic processes. This is because the 3D‐printed electrode has an open structure that ensures excellent coverage of functional groups on carbon surface and facilitates the ion accessibility of these surface functional groups even at high current densities and large mass loading/electrode thickness. An asymmetric device assembled with SF‐3D GA as anode and 3D‐printed GA decorated with MnO2 as cathode achieves a remarkable energy density of 0.65 mWh cm−2 at an ultrahigh power density of 164.5 mW cm−2, outperforming carbon‐based supercapacitors operated at the same power density.

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Additive manufacturing is used to overcome inherent aerogel limitations. 3D printed aerogels simultaneously exhibit large capacitance and fast ion transport in millimeter-thick electrodes.