Superior Rate Mesoporous Carbon Sphere Array Composite via Intercalation and Conversion Coupling Mechanisms for Potassium‐Ion Capacitors

Abstract

Carbonaceous materials have been usually adopted as the anode for high energy density potassium-ion hybrid capacitors (KICs) owing to their low voltage plateau, high conductivity, and excellent electrochemical compatibility. The improvements of their specific capacity and sluggish intercalation mechanism are still challenges to further boost the energy density of KICs while maintaining high power density and long cycle life. Herein, a N-doped mesoporous carbon sphere array composite is developed by a dual-templates method. The N-doped carbon sphere array with interpenetrated macro-and meso-pores facilitates the fast electron transport and rapid K + diffusion. The uniformly introduced Co 3 O 4 nanoparticles (NPs) confined in the array enable a kinetically boosted conversion reaction for excess and fast K + storage. The partially oxidized Co NPs can efficiently enhance the conductivity of the entire composite. By introducing this optimized conversion capacity from encapsulated Co 3 O 4 NPs, the composite with intercalation and conversion coupling mechanisms displays superior capacity and cycle life. The assembled KICs exhibit high energy/power densities (148 Wh kg −1 /124 W kg −1 ) and great cycling performance (94% after 5000 cycles, 0.5 A g −1 ). This promising strategy demonstrates an example for carbonaceous composite anode with synergistic K + storage hybrid mechanism toward high performance KICs.

Assembly: A Key Enabler for the Construction of Superior Silicon‐Based Anodes

“…Besides the independent soft template assembly method, N-doped mesoporous carbon sphere array composite (NMCSA@Co/Co 3 O 4 ) can also be synthesized by a dual-templates assembly method, in which the macroporous silica inverse opal is employed as the hard template and amphiphilic triblock copolymer Pluronic F127 is employed as the soft template (Figure 3b). [80] Chemical vapor deposition (CVD) is the process of depositing vaporous substances on the gas phase or gas-solid interface. The CVD strategy is widely used in various fields, due to its ability that effectively and finely control the structure of the final product by adjusting the precursor source, deposition temperature, and reaction rate.…”

Surface Redox Pseudocapacitance Boosting Vanadium Nitride for High‐Power and Ultra‐Stable Potassium‐Ion Capacitors

“…The energy-power performance of VN@CFs||ACFs is superior to other PICs reported before, such as MoP@NC-1||AC, MDPC||PDPC, TiO 2 / NC-HN||AC, KNO||OPAC, NbSe 2 NSeCNFs||AC, NMCSA@ Co 3 Co 4 ||AC, and P-O-PCS||AC (Figure 5e; Table S3, Supporting Information). [42,44,[53][54][55][56][57] The long cycling stability of PICs was further investigated at the current density of 4.0 A g -1 . The capacity retention of 86.8% after 15 000 cycles (0.00088% capacity fading per cycle) shows the excellent cycle stability of the VN@CFs||ACFs PIC (Figure 5f).…”

K+ Induced Phase Transformation of Layered Titanium Disulfide Boosts Ultrafast Potassium‐Ion Storage

“…have successfully been developed for K-DIBs. [9][10][11][12][13][14][15][16][17] However, these materials have serious inherent bottlenecks that limit their application. For examples, voltage polarization and safety issues for K metal plating at low voltages and high rates are the major challenges for carbon materials; the main disadvantage of alloys and transition metal oxide materials is the large volume expansion, resulting in poor cycle performance; the main challenges of organicbased materials are low conductivity and solubility in organic electrolytes.…”