An Ultrastable Nonaqueous Potassium‐Ion Hybrid Capacitor

Abstract

Potassium-ion hybrid capacitors (PIHCs) show great potential in largescale energy storage due to the advantages of electrochemical capacitors and potassium-ion batteries. However, their development remains at the preliminary stage and is mainly limited by the kinetic imbalance between the two electrodes. Herein, an architecture of NbSe 2 nanosheets embedded in N, Se co-doped carbon nanofibers (NbSe 2 /NSeCNFs) as flexible, free-standing, and binder-free anodes for PIHCs is reported. The NbSe 2 /NSeCNFs with hierarchically porous structure and N, Se co-doping afford highly efficient channels for fast transportation of potassium ions and electrons during repeated cycling process. Furthermore, excellent electrochemical reversibility of the NbSe 2 /NSeCNFs electrode is demonstrated through in situ XRD, in situ Raman, ex situ transmission electron microscopy and element mapping. Thus, PIHCs with the NbSe 2 /NSeCNFs anode and active carbon cathode achieve a high energy of 145 W h kg −1 at a current density of 50 mA g −1 , as well as an ultra-long cycle life of over 10 000 cycles at a high current density of 2 A g −1. These results indicate that the assembled PIHCs display great potential for applications in the field of ultra-long cycling energy storage devices.

Phosphorus and Oxygen Dual‐Doped Porous Carbon Spheres with Enhanced Reaction Kinetics as Anode Materials for High‐Performance Potassium‐Ion Hybrid Capacitors

“…Such excellent rate capability and energy output are superior to many reported state‐of‐the‐art hybrid capacitors, as summarized in Figure 6d. [ 52–60 ] In addition, the constructed device also shows an exceedingly high‐capacity retention of 94.5% after 30 000 cycles at 5 A g −1 with a Coulombic efficiency above 99% (Figure 6e). Meanwhile, light‐emitting diode (LED) arrays can be successfully illuminated by two lab‐assembled PIHCs connected in series (see the inset in Figure 6e).…”

“…d) Ragone plots of different hybrid capacitors according to previous works. [ 52–60 ] e) Long‐term cycle performance of the P/O‐PCS//AC device at 5 A g −1 up to 30 000 cycles. The inset displays the illuminated LED arrays powered by our fabricated P/O‐PCS//AC device.…”

3D Holey Graphene/Polyacrylonitrile Sulfur Composite Architecture for High Loading Lithium Sulfur Batteries

“…The ever‐growing demands for portable electronics and electric vehicles prompt researchers to develop environment friendly, safe, and high‐density energy storage devices. [ 1–11 ] Lithium sulfur (Li–S) batteries, due to high theoretical specific capacity (1675 mAh g −1 , up to four times than that of the commercial lithium‐ion batteries) and high energy density (2600 Wh kg −1 , up to six times than that of commercial lithium‐ion batteries (387 Wh kg −1 for LiCoO 2 /graphite battery)), have attracted considerable interest as the next‐generation high‐density energy storage devices for plug‐in hybrid and all‐electric vehicles. [ 12–16 ] However, the inherent challenges of cathode materials hinder its practical application.…”

A General Self-Sacrifice Template Strategy to 3D Heteroatom-Doped Macroporous Carbon for High-Performance Potassium-Ion Hybrid Capacitors

“…Moreover, the A-Se/N-3DMpC//Se/N-3DMpC PIHCs displayed the highest energy density of 186 Wh kg −1 (at power density of 100 W kg −1 ) and can maintain an energy density of 91 Wh kg −1 even at a high power density of 8100 W kg −1 , which surpass most of the previously reported PIHCs (Fig. 5d) [17,20,24,34,53,[55][56][57][58]. The excellent energy and power densities output of the PIHCs can bridge the gap between high-energy rechargeable batteries and high-power supercapacitors (Fig.…”