Macro‐ and Nano‐Porous 3D‐Hierarchical Carbon Lattices for Extraordinarily High Capacitance Supercapacitors

Abstract

Supercapacitors, which can be charged/discharged rapidly, play important roles in a sustainable society. Thick electrodes can reduce the ratio of inactive components in the overall cell while simultaneously improving energy and power densities. However, thick electrodes induce longer ion diffusion pathways, and capacitance drops dramatically after a certain thickness. To overcome this, precisely designed macro-and nano-porous 3D-hierarchical carbon lattices, where ions can diffuse freely inside the electrode, are prepared by combining an inexpensive stereolithography-type 3D printer, whose resolution is 50 µm, with a simple CO 2 activation process. The activated 3D carbon lattice with a 66% burn-off ratio (3D-CL-A66%) has ordered macropores (≈150 µm) and uniform nanopores (2-3 nm), exhibiting a maximum areal capacitance of 5251 mF cm -2 at 3 mA cm -2 . Furthermore, manganese oxide is electrochemically deposited on 3D-CL-A16% for 8 min (3D-CL-A16%-MnO 2 -8 min), increasing the areal capacitance by 2.5-times. Finally, an all-3D-printed asymmetric 1.8 V supercapacitor is prepared by combining 3D-CL-A16%-MnO 2 -8 min and 3D-CL-A66% as the positive and negative electrodes, respectively, demonstrating a maximum energy density of 0.808 mWh cm -2 at a power density of 2.48 mW cm -2 . The achieved values are one of the highest areal energy and power densities reported so far.

High performance supercapacitors based on wood-derived thick carbon electrodes synthesized via green activation process

“…Altogether, the overall capacitive properties of the a-OC-900 electrode were comparable and even higher than most carbon-based electrodes with high mass loading (Table S3†), such as CMCNs (12.5 mg cm −2 , 125 μm), 47 SLC-7 (13.6 mg cm −2 ), 48 CW-P-9.24 (17.17 mg cm −2 , ∼800 μm), 23 WC-E-100-48 (∼25 mg cm −2 , ∼800 μm), 22 AWC (30 mg cm −2 , 1 mm), 49 and 3D-CL-A66% (46.2 mg cm −2 , 1.5 mm). 50…”

“…Altogether, the overall capacitive properties of the a-OC-900 electrode were comparable and even higher than most carbon-based electrodes with high mass loading (Table S3 †), such as CMCNs (12.5 mg cm −2 , 125 μm), 47 SLC-7 (13.6 mg cm −2 ), 48 CW-P-9.24 (17.17 mg cm −2 , ∼800 μm), 23 WC-E-100-48 (∼25 mg cm −2 , ∼800 μm), 22 AWC (30 mg cm −2 , 1 mm), 49 and 3D-CL-A66% (46.2 mg cm −2 , 1.5 mm). 50 a-OC-900 was prepared by the hydrothermal activation of OC-900 with the conditions of 1% H 2 O 2 at 180 °C for 12 h (hereafter, a-OC-1%, a-OC-12 h, and a-OC-180 °C also refers to a-OC-900). Various factors such as activator concentration, activation time, and temperature affected the final capacitive performance of the activated product.…”

Vertical Growth of 2D Covalent Organic Framework Nanoplatelets on a Macroporous Scaffold for High‐Performance Electrodes

“…This ultralong work life and cyclic stability are among the best level of EDLC capacitors and outperform most of the reported COF-based pseudocapacitors and batteries (Figure 5h). [14][15][16][17]39,[66][67][68][69][70][71][72][73][74] This superior cycling performance demonstrates the outstanding chemical and structural stability of COF NPs, and their strong interface interaction with graphene scaffolds. The capacitive performances of v-COF-GAs capacitor cells were compared with other reported supercapacitors in the Ragone plot (Figure 5i and Figure S19, Supporting Information).…”

“…[10,11] Therefore, hierarchical pore-structure engineering that coordinates structural features spanning multiple length scales is crucial for developing high-performance electrodes. [11][12][13][14] Despite significant progress made in regulating either microscale or macroscale structure, [13][14][15][16][17][18] simultaneously tailoring the mesoscale structure to achieve full-scale engineering of the electrode remains a great challenge.…”

A 3D‐Printed, Freestanding Carbon Lattice for Sodium Ion Batteries

“…[17] Nevertheless, it still remains a challenging goal to simultaneously achieve high performance and low cost as they generally conflict with each other.One possible way to achieve this goal is to increase the mass loading of active materials in a single cell (Figure 1). [18][19][20][21][22][23][24][25] A single cell with 5 times thicker electrodes, instead of a stack of 5 cells, can reduce the amount of inactive components (separator, current collector, tabs, etc.) to one fifth, downsizing the overall cell size while saving as much as 26.1% of the cost per battery as shown in Table 1.…”