Russian‐Doll‐Like Porous Carbon as Anode Materials for High‐Performance Potassium‐Ion Hybrid Capacitors

Abstract

as new storage devices by assembling battery-type and capacitor-type electrodes that can meet requirements while deliver high energy at high power without sacrificing their service life. [8] Among them, potassium-ion hybrid capacitors (PIHC) have attracted much attention due to low cost, much higher crustal abundance (CLARKE value) than that of lithium (1.5% > 0.0017%), lower redox potential (−2.93 V K/K + vs SHE; −3.04 V, Li/Li + vs SHE). In particular, hydrated K-ion has the smallest Stokes radius (3.6 Å) compared with Liand Na-ions (4.8 Å and 4.6 Å), demonstrating the great transport properties in aqueous electrolytes. [9][10] More strikingly, aqueous electrolyte rechargeable devices meet the inherent safety and low-cost requirement but suffer from low-capacity issues. Despite some progress, there are still few reports of aqueous potassium-ion hybrid capacitors. [11,12] Recent research attention focused on carbonaceous materials in the field of potassium-ion systems because of their multifarious structural configurations, low cost and excellent physical/chemical stability, sufficient surface area, and excellent electrolyte channels. [13][14][15] On this basis, dual-carbon potassium-ion hybrid capacitors (DC-PIHCs), whose cathode and anode are carbon materials, show the most promising industrial prospects in view of the greatly reduced overall cost of device, competitive K + storage performance and intrinsic long-term cycle stability. [16,17] However, the inescapable fact is that a much larger radius of K + (1.38 Å for K + vs 0.76 Å for Li + ) conspicuously hinders the intercalation behavior of anode materials, leading to the sluggish kinetics and inadequate power density. Even worse, a significant volume expansion (up to 60%) [18] can cause carbon skeletons structural failure and significant capacity fading, which is unfavorable for long lifespan. To tackle these challenges, it is vital to exploit suitable host materials with satisfactory properties for DC-PIHCs.To overcome the aforementioned obstacles, cationic species (Na + , K + , Al 3+ ) pre-intercalation, as one important strategy, enables the carbon anode to accommodate large-sized K + , thus facilitates the charge carrier kinetics and ensure structural stability. [19][20][21] Moreover, porous structure also affects K + migration behavior. [22] As reported, carbon-based anode materials with porous architectures could accommodate huge volume strain, provide good pathways for fast mass transport, and expose Pore-structure design with the sophisticated and pragmatic nanostructures still remains a great challenge. In this work, porous carbon with Russiandoll-like pores rather than traditional single modal is fabricated via a boiling carbonization approach, accompanied by K + -pre-intercalation. The most important internal factor is that alkali can penetrate into the stereoscopic space of layered Malonic acid dihydrazide and the confinement effect leads to the in-depth development of different dimensional pore structures. The oxygenated and nitrogenated surfa...

Tuning nitrogen species in 3D porous carbon via boron doping for boosted Zn-ion storage capability

“…The C 1s spectra of BENC 5 (Fig. 2d 29,40,41 For B 1s XPS spectra (Fig. 2e), two peaks were attributed to the functional groups of B-C (190.8 eV) and B-O (192.1 eV).…”

“…2d) arise from five components surrounding C–B (283.1 eV), CC (284.6 eV), C–C (286.1 eV), C–N (288.4 eV), and OC–O (291.2 eV), further confirming the successful doping of B and N atoms. 29,40,41 For B 1s XPS spectra (Fig. 2e), two peaks were attributed to the functional groups of B–C (190.8 eV) and B–O (192.1 eV).…”

Advanced Electrode Materials for Potassium‐Ion Hybrid Capacitors

“…Recently, Liu et al prepared porous carbon with Russian-doll-like pores pre-intercalated with K + through an ebullient carbonization process. [50] The main internal factor is that the alkali can penetrate the three-dimensional space of dihydrazine malonate layer by layer. The confinement effect forms deep pore structures of different dimensions.…”

Amorphous Thin-Walled Carbon Nanotubes Modified by Simple Oxidation for Zinc-Ion Hybrid Supercapacitors

“…Sustainable electrochemical energy storage systems are increasingly emerging in modern society, among which supercapacitors have attracted extensive attention due to high power density, long cycle life, and short charge–discharge time. − Nevertheless, the potential application of conventional capacitors is impeded by the low energy density (about 5–8 Wh kg –1 ). − Recently, ion-based hybrid supercapacitors, a promising candidate device, are compatible with the advantages of supercapacitors and secondary batteries so as to have excellent energy density, outstanding power density, and long cycle life, which promotes the development of conventional electrochemical energy storage equipment. , For the past few years, lithium/sodium/potassium-ion hybrid supercapacitors have been reported in succession. , However, these alkali metals are very active, relatively expensive, and unnoticeably dangerous. Recent studies show that energy storage equipment containing polyvalent ions (Zn 2+ , Al 3+ , Ca 2+ , and Mg 2+ ) possesses faster charge transfer rate and more reactive ions than univalent ions (Li + , Na + , and K + ).…”

“…8,9 For the past few years, lithium/sodium/potassium-ion hybrid supercapacitors have been reported in succession. 10,11 However, these alkali metals are very active, relatively expensive, and unnoticeably dangerous. Recent studies show that energy storage equipment containing polyvalent ions (Zn 2+ , Al 3+ , Ca 2+ , and Mg 2+ ) possesses faster charge transfer rate and more reactive ions than univalent ions (Li + , Na + , and K + ).…”