Harmonized edge/graphitic‐nitrogen doped carbon nanopolyhedron@nanosheet composite via salt‐confined strategy for advanced K‐ion hybrid capacitors

Abstract

Nitrogen doping has readily emerged as an efficient solution to boost potassium‐ion storage of carbonaceous materials. Nevertheless, the capacity and lifespan enhancement of derived electrodes is still plagued by the incompetent in coordinating the dopant configurations. In the realm of emerging potassium‐ion hybrid capacitor (PIHC) device, dictating nitrogen doping to enhance pseudocapacitive behavior and improve K+ diffusion kinetics of carbonaceous anodes is scarcely demonstrated. Herein, we report the design of hierarchical N‐doped carbon nanopolyhedron@nanosheet composite via a salt‐confined synthetic strategy with tunable doping configurations toward advanced PIHC anode. A harmonized edge‐ to graphitic‐nitrogen ratio in such dual‐carbon materials enables outstanding rate capability (130 mAh g−1 at 10.0 A g−1) and cyclic performance (with a capacity retention of 80% after 2000 cycles at 5.0 A g−1) in half‐cell tests. As expected, the thus‐assembled PIHC full device with a working voltage of 4.2 V presents a high energy/power density (146 Wh kg−1/8000 W kg−1) and favorable cyclicability. This work is anticipated to offer an innovative insight into the coordination of nitrogen doping configurations in heteroatom‐doped carbon anode targeting high‐performance PIHC applications.

Dimensional engineering of anode materials for high performance potassium ion hybrid capacitor—A review

“…Zhao et al designed a 3D composite PIHC anode composed of layered N-doped nano-polyhedron and carbon nanosheet, and studied the pseudocapacitance behavior and improved potassium ion diffusion kinetics of N-doped carbon anode. 16 In addition, we found that Yu et al and Li et al synthesized a PIHC anode with a similar bowl-shaped structure (denoted as CoP@NPC BIB and MoSe 2 & CNB, respectively) (Figure 7E-G,J-L). 126,127 The bowl-shaped structure is not only conducive to the rapid transfer of electrons and ions, but also can withstand the volume expansion and contraction during the process of potassiation and depotassiation.…”

“… 125 This work suggested that the utilize of rGO avoids the number of conductive adhesives and reduces the internal resistance between the collector and the electrode material, while the 3D nanostructure enables the extension of extreme active sites in electrochemical reactions to achieve higher storage space (Figure 7C,D). Zhao et al designed a 3D composite PIHC anode composed of layered N‐doped nano‐polyhedron and carbon nanosheet, and studied the pseudocapacitance behavior and improved potassium ion diffusion kinetics of N‐doped carbon anode 16 …”

“…8 Therefore, many works have focused on synthesizing electrode materials with higher stability, richer surfaceactive sites, and larger specific surface area to reduce the severe impacts of large radius in PIHCs. [9][10][11][12][13][14][15][16][17] Generally speaking, PIHC anode materials conforming to these characteristics can be divided into carbon materials and non-carbon materials. Among them, carbon materials are divided into hard carbon 18,19 and soft carbon, 20,21 while non-carbon materials are composed of metal oxides, [22][23][24] metal sulfides 25,26 and some organic materials.…”

“…Therefore, many works have focused on synthesizing electrode materials with higher stability, richer surface‐active sites, and larger specific surface area to reduce the severe impacts of large radius in PIHCs 9‐17 . Generally speaking, PIHC anode materials conforming to these characteristics can be divided into carbon materials and non‐carbon materials.…”

Homologous Nitrogen‐Doped Hierarchical Carbon Architectures Enabling Compatible Anode and Cathode for Potassium‐Ion Hybrid Capacitors

“…As for the production of the anode candidate, saturated NaCl salt solution with uniformly distributed zeolitic imidazolate framework‐8 (ZIF‐8) crystals was successively recrystallized, dried, and carbonized. [ 39 ] Note that the NaCl crystal, functioning as the reactor of ZIF‐8 decomposition at elevated temperature, suppresses the loss of intermediate species and accordingly results in the formation of graphitic‐like carbon nanosheets wrapped over the surface of carbon polyhedron (M‐NC). [ 40–42 ] Meanwhile, ANC was obtained via KOH activation of the bare ZIF‐8‐derived NC material.…”