Kinetics Enhanced Nitrogen‐Doped Hierarchical Porous Hollow Carbon Spheres Boosting Advanced Potassium‐Ion Hybrid Capacitors

Abstract

Potassium-ion hybrid capacitors (PIHCs) shrewdly combine a battery-type anode and a capacitor-type cathode, exhibiting an energy density close to that of potassium ion batteries and a comparable power density of supercapacitors. However, the rosy scenario is compromised by the sluggish kinetics in the PIHCs device. Herein, the kinetics enhanced nitrogen-doped hierarchical porous hollow carbon spheres (NHCS) are synthesized and successfully applied to PIHCs. As for the K half-cell, NHCS anchored with sodium alginate delivers excellent electrochemical performance. Further evaluation shows that the binder can significantly affect the potassium storage performance of NHCS by adjusting the coatability and ionic conductivity of the NHCS anode. Moreover, kinetic analysis and density functional theory calculations reveal the origin of the superior electrochemical properties of NHCS. As expected, an advanced PIHC device is assembled with a NHCS anode and an activated NHCS cathode, demonstrating an exceptionally high energy/power density (114.2 Wh kg −1 and 8203 W kg −1 ), along with a long-life capability. The successful construction of high-performance PIHCs in this work opens a new avenue for the development and application of PIHCs in the future.

Rational Construction of Nitrogen‐Doped Hierarchical Dual‐Carbon for Advanced Potassium‐Ion Hybrid Capacitors

“…[ 1,2 ] Potassium‐ion hybrid capacitors (PIHCs), which integrate the merits of high‐power density as well as ultralong life‐span of supercapacitors and high energy density of potassium ion batteries (PIBs), have attracted much attention and shown great potential. [ 3,4 ] Concerning device structure, PIHCs shrewdly combine a capacitor‐type cathode and battery‐type anode, which means that the properties of the cathode and anode determine the practical application of the PIHCs. [ 5,6 ] Commercial activated carbon (AC) has been selected as the capacitor‐type cathode and has shown favorable performance.…”

A Site‐Selective Doping Strategy of Carbon Anodes with Remarkable K‐Ion Storage Capacity

“…Furthermore, edge‐nitrogen (pyrrolic, and pyridinic) doping, as demonstrated by calculation and experimental study, has higher adsorption energy than sp 2 hybridized graphitic nitrogen doping . However, the state‐of‐art pyrolysis methods for preparing nitrogen‐doped carbons from nitrogen‐abundant organics are mostly done by trial and error approaches . In these approaches, the nitrogen doping of carbonaceous products cannot be precisely tuned into edge‐nitrogen configurations.…”

A Site‐Selective Doping Strategy of Carbon Anodes with Remarkable K‐Ion Storage Capacity

“…[31,32] However, the state-of-art pyrolysis methods for preparing nitrogen-doped carbons from nitrogen-abundant organics are mostly done by trial and error approaches. [31,[33][34][35] In these approaches, the nitrogen doping of carbonaceous products cannot be precisely tuned into edge-nitrogen configurations. For instance, low-temperature pyrolysis (around 650 8C) of polypyrrole, which is typical precursor of nitrogen-doped carbons, [32] leads to high nitrogen doping level (13.8 %), but low edge-nitrogen doping ratio (55 %).…”