Abstract:Potassium-ion
batteries (PIBs) have received significant attention
because of the abundant potassium reserves and similar electrochemistry
of potassium to that of lithium. Because of the open framework and
structural controllability, Prussian blue and its analogues (PB) are
considered to be competitive cathodes of PIBs. However, the intrinsic
lattice defects and poor electronic conductivity of PBs induce poor
cycling performance and rate capability. Herein, we propose a polypyrrole-modified
Prussian blue mater… Show more
“…In terms of anode materials, so far carbonaceous materials, alloy‐based materials, conversion‐type materials, and organic materials have been widely studied. As for cathodes materials, there are mainly four categories which have been developed and evaluated, that is , Prussian blue (PB) and its analogs, layered metal oxides, poly‐anion oxides, and organic compounds . Though high capacities (e.g., ≥300 mAh g −1 ) can be readily achieved for the anode materials, the inferior capacities for cathodes, which is usually less than of 100 mAh g −1 , dramatically drive the energy densities of the full PIBs to an unsatisfactory level.…”
Potassium‐ion batteries (PIBs) as a promising supplement to lithium‐ion batteries have drawn great attention attributing to the abundant potassium resources, the fast‐ionic conductivity of potassium ions in electrolyte, and the low standard redox potential of potassium. However, the development of PIBs is still in its infancy, which is largely restricted by the fact that the electrode materials, especially the cathode materials of PIBs, are far from satisfactory in practical applications regarding the capacity, voltage, and cycle life. Therefore, most of current research efforts have been devoted to exploring new and high‐performance electrode materials for achieving PIBs with high capacity and voltage as well as excellent cyclability. In this review, the recent advancements on cathode materials for PIBs are specially summarized. Besides, technological developments, scientific challenges, and future research opportunities of cathode materials for PIBs are also briefly outlooked.
“…In terms of anode materials, so far carbonaceous materials, alloy‐based materials, conversion‐type materials, and organic materials have been widely studied. As for cathodes materials, there are mainly four categories which have been developed and evaluated, that is , Prussian blue (PB) and its analogs, layered metal oxides, poly‐anion oxides, and organic compounds . Though high capacities (e.g., ≥300 mAh g −1 ) can be readily achieved for the anode materials, the inferior capacities for cathodes, which is usually less than of 100 mAh g −1 , dramatically drive the energy densities of the full PIBs to an unsatisfactory level.…”
Potassium‐ion batteries (PIBs) as a promising supplement to lithium‐ion batteries have drawn great attention attributing to the abundant potassium resources, the fast‐ionic conductivity of potassium ions in electrolyte, and the low standard redox potential of potassium. However, the development of PIBs is still in its infancy, which is largely restricted by the fact that the electrode materials, especially the cathode materials of PIBs, are far from satisfactory in practical applications regarding the capacity, voltage, and cycle life. Therefore, most of current research efforts have been devoted to exploring new and high‐performance electrode materials for achieving PIBs with high capacity and voltage as well as excellent cyclability. In this review, the recent advancements on cathode materials for PIBs are specially summarized. Besides, technological developments, scientific challenges, and future research opportunities of cathode materials for PIBs are also briefly outlooked.
“…On the other hand, remarkable progress in PBAs used in the application of electrochemical energy has been made, because of the wide interstitial sites of PBAs that can store mono‐ or multi‐valence metals. Therefore, PBAs are increasing the applications of ion batteries, such as potassium and lithium ion batteries …”
The structural properties of CoFe composites fabricated from inexpensive Co(II) and Fe(III) precursors using a Prussian blue analogue (PBA) strategy without additional reductants were investigated. Microporous CoFe-200 and microporous/mesoporous CoFe-550 structures of the CoFe catalysts (CoFe-PBA) were produced by calcination for 1 h in N 2 at 200°C or 550°C, respectively. The electrocatalytic activities of the CoFe catalysts produced for the oxygen evolution and reduction reactions (OER/ORR) were studied in alkaline media. The OER measurements revealed the CoFe-200 catalyst to be superior to CoFe-PBA and CoFe-550, and even surpass the activity of commercial Ir/C in terms of the overpotential at 10 mA cm À 2 and onset potential (E OER onset). On the other hand, the ORR activity of CoFe-550 exhibited a more positive half-wave potential (0.837 V vs. RHE) and E ORR onset (0.942 V vs. RHE) than CoFe-200. The Tafel slope (À 55.9 mV dec À 1) of CoFe-550 was lower than that of Pt/C (À 77.8 mV dec À 1). A comparison of CoFe-200 and CoFe-550 suggested that the microporosity of CoFe-200 (average pore diameter, d � 2 nm) was beneficial in terms of the OER. In contrast, the mesoporous (d � 35.6 nm) structure of CoFe-550 promoted the mass-transport kinetics of oxygen through the electrode surface. CoFe nanocubes with tunable porosity are potential catalysts that can be utilized selectively for the OER and ORR.
“…Meanwhile, the low crystallization and small particle size make it difficult to obtain uniform and effective surface coating. Considering these limitations, Xue et al [ 95 ] proposed a polypyrrole (PPy) coating approach for K‐rich PBAs (K 1.87 Fe[Fe(CN) 6 ]) cathode materials in PIBs. High‐resolution transmission electron microscopy (HRTEM) confirms the growth of an ultrathin and homogeneous PPy coating layer on the coarse surface of PBA nanocubes ( Figure a–c).…”
Section: Improvement Strategies To Endow Pbas As High‐performance Catmentioning
confidence: 99%
“…Reproduced with permission. [ 95 ] Copyright 2019, American Chemical Society. d) Schematic illustration of the Ni‐doping strategy and the relevant structural change.…”
Section: Improvement Strategies To Endow Pbas As High‐performance Catmentioning
Potassium‐ion batteries (PIBs) are emerging as one of the potential alternatives to lithium‐ion batteries for next‐generation rechargeable battery systems. Nevertheless, the lack of suitable cathode materials with high capacity hinders their practical applications. Recently, Prussian blue analogs (PBAs) cathode materials stand out as promising candidates for PIBs. Their unique crystal structure with open 3D frameworks and large interstitial voids favors fast K+ intercalation without causing drastic volume expansion, which is the prerequisite for high‐rate and long‐term battery operation. Herein, a fundamental review on the development and advance of PBAs cathode materials is presented for PIBs with in‐depth elucidation of their crystal structures, chemical compositions, and electrochemical performances. Particularly, the unique and prominent advantages of PBAs in both aqueous and nonaqueous PIBs are highlighted. In addition, to bridge the current gap from the laboratory to future commercialization, potential improvement strategies are proposed to overcome the present drawbacks. Finally, perspectives and new insights are provided for further exploration and research in PBAs for better PIBs.
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