Graphene-based in-plane micro-supercapacitors with high power and energy densities

Abstract

Micro-supercapacitors are important on-chip micro-power sources for miniaturized electronic devices. Although the performance of micro-supercapacitors has been significantly advanced by fabricating nanostructured materials, developing thin-film manufacture technologies and device architectures, their power or energy densities remain far from those of electrolytic capacitors or lithium thin-film batteries. Here we demonstrate graphene-based in-plane interdigital micro-supercapacitors on arbitrary substrates. The resulting micro-supercapacitors deliver an area capacitance of 80.7 μF cm−2 and a stack capacitance of 17.9 F cm−3. Further, they show a power density of 495 W cm−3 that is higher than electrolytic capacitors, and an energy density of 2.5 mWh cm−3 that is comparable to lithium thin-film batteries, in association with superior cycling stability. Such microdevices allow for operations at ultrahigh rate up to 1,000 V s−1, three orders of magnitude higher than that of conventional supercapacitors. Micro-supercapacitors with an in-plane geometry have great promise for numerous miniaturized or flexible electronic applications.

Ultrahigh‐Power Pseudocapacitors Based on Ordered Porous Heterostructures of Electron‐Correlated Oxides

“…The increment of volumetric capacitance depends on the loading amount of the pseudocapacitive MnO 2 and increases with the electroplating time (Figure 3d). When the mass ratio of MnO 2 increases to ≈47 wt%, a volumetric capacitance as high as ≈1172 F cm −3 is achieved at a scan rate of 10 mV s −1 for the NP V 2 O 3 /MnO 2 with thickness of 2 μm, comparable to 1160 F cm −3 for 100 nm‐thick NP Au/MnO 2 ultrathin films at a scan rate of 50 mV s −1 54 and much higher than some of the highest reported previously: 900 F cm −3 for Ti 3 C 2 T x clay electrodes at a scan rate of 2 mV s −1 ,7 78.6 F cm −3 for MnO 2 /Au multilayers at a scan rate of 10 mV s −1 ,25 246 F cm −3 for layer‐by‐layered MWNT/MnO 2 electrodes at a scan rate of 10 mV s −1 ,28 and 71.6 F cm −3 for reduced graphene films at 10 mV s −1 10. For comparison, the volumetric capacitances of MnO 2 nanocrystals electrodeposited on SS sheets with different time and heat‐treated at the same H 2 /Ar atmosphere are also included in Figure 3d.…”

“…Unlike electrochemical double‐layer capacitors (EDLCs),8, 9, 10, 11, 12 in which charge storage is achieved by nonfaradaic electrostatic adsorption in nanostructured carbons with low intrinsic capacitance (≈20 μF cm −2 carbon ),1, 13, 14 pseudocapacitors store high‐density energy on pseudocapacitive materials by fast and reversible surface redox reactions at or near the electrode/electrolyte interface 1, 2, 3, 4, 5, 6, 7, 15, 16, 17. The surface mechanisms are fundamentally distinguished from rate‐limited volumetric reactions in batteries by short charge/discharge time, high power density and long‐term cycling stability 1, 2, 3, 18.…”

Ultrafast‐Charging Supercapacitors Based on Corn‐Like Titanium Nitride Nanostructures

“…The very high power density of our TiN supercapacitors, 150 W cm −3 at an energy density of 0.30 mWh cm −3 , implies the capability of discharging within an extremely short time (14 ms). Detailed comparisons are listed in Table S1 (Supporting Information) 5, 6, 7, 8, 28, 29, 30, 31, 32. To our best knowledge, this is the first report of noncarbon supercapacitors without microconfiguration having such excellent performance in terms of ultrahigh power and energy densities.…”

On‐Chip Micro‐Pseudocapacitors for Ultrahigh Energy and Power Delivery

“…In contrast to thin film batteries whose properties drop dramatically with the decrease of sizes, micro‐supercapacitors often have better performance in comparison with their bulk counterparts as the result of reduced transport length of charge and electrolytes 1, 2. Interdigital planar form micro‐supercapaciotors (MSCs) with active carbon,3 carbide‐derived carbon,4 carbon nanoparticles/nanotubes2, 5, 6, 7 and multilayer graphene7, 8, 9, 10, 11, 12, 13 as electrode materials have been developed and are capable of delivering high power density by electrochemical double layer charge storage. However, their energy densities, typically, 0.1–1.0 mW h cm −3 , are insufficient to meet the requirement of the reasonable operational time of microdevices.…”