Construction of Hierarchical K_1.39Mn₃O₆ Spheres via AlF₃ Coating for High‐Performance Potassium‐Ion Batteries

Abstract

Potassium‐ion batteries are attracting great interest for emerging large‐scale energy storage owing to their advantages such as low cost and high operational voltage. However, they are still suffering from poor cycling stability and sluggish thermodynamic kinetics, which inhibits their practical applications. Herein, the synthesis of hierarchical K1.39Mn3O6 microspheres as cathode materials for potassium‐ion batteries is reported. Additionally, an effective AlF3 surface coating strategy is applied to further improve the electrochemical performance of K1.39Mn3O6 microspheres. The as‐synthesized AlF3 coated K1.39Mn3O6 microspheres show a high reversible capacity (about 110 mA h g−1 at 10 mA g−1), excellent rate capability, and cycling stability. Galvanostatic intermittent titration technique results demonstrate that the increased diffusion kinetics of potassium‐ion insertion and extraction during discharge and charge processes benefit from both the hierarchical sphere structure and surface modification. Furthermore, ex situ X‐ray diffraction measurements reveal that the irreversible structure evolution can be significantly mitigated via surface modification. This work sheds light on rational design of high‐performance cathode materials for potassium‐ion batteries.

ZIF‐8@ZIF‐67‐Derived Nitrogen‐Doped Porous Carbon Confined CoP Polyhedron Targeting Superior Potassium‐Ion Storage

“…In the next two cycles, only one peak at 0.23 V in the cathodic scan and one peak at 1.88 V in the anodic scan is discernible, respectively, corresponding to the potassiation and depotassiation process of the composites. The galvanostatic charge/discharge curves for the first three cycles under a current density of 0.1 A g −1 accord well with the CV results, manifesting sloping plateaus Small 2020, 16,1906566 at ≈0.25 and ≈1.9 V in the discharge and charge process, respectively ( Figure S10, Supporting Information). Figure 4b shows the rate performances of NC, CoP/NC and NC@CoP/ NC electrodes under various current densities ranging from 50 to 2000 mA g −1 .…”

“…In contrast, CoP/NC electrode presents a rapid decay with an inferior capacity retention of 41%. To justify the structural stability of the NC@CoP/NC electrode, morphological inspections were carried out prior to and after the cycling by SEM and TEM, which show barely no sign for structural collapse and particle aggregation ( Figure S13, Supporting Small 2020, 16,1906566 Information). To further clarify the electrochemical kinetics of the NC@CoP/NC electrode, the pseudocapacitive contribution was probed by carrying out CV scans at sweep rates ranging from 0.1 to 1.2 mV s −1 (Figure S14, Supporting Information).…”

“…Interestingly, it can be found that the intercalation of K ions is energetically unfavorable, indicating that the K ion storage does not occur in the CoP bulk. To further investigate the ion conductivity of CoP surface, the ionic diffusion Small 2020, 16,1906566…”

“…In this respect, tremendous efforts have been exerted to explore novel anode materials with high specific capacity, facile K-ion uptake/release kinetics and structural robustness targeting high energy and long life KIBs. [6][7][8] Amongst a wide suite of employed anode materials for KIBs, including carbonaceous materials, [9][10][11][12][13][14][15] metal oxides, [16][17][18] transitional metal dichalcogenides, [19][20][21][22][23][24] and metal phosphides, phosphide-based species have garnered a growing research interest because of their high theoretical capacity, cost-effectiveness, and favorable ion/electron conductivity. [25][26][27][28][29] However, these materials, in particular transition metal phosphides (TMPs), normally experience severe agglomeration and large volume expansion during potassiation process, giving rise to fast capacity decay upon long-life cycling.…”

Boosting Superior Lithium Storage Performance of Alloy‐Based Anode Materials via Ultraconformal Sb Coating–Derived Favorable Solid‐Electrolyte Interphase

“…[10][11][12][13][14][15][16][17][18][19][20][21] For example, the capacity of Si nanowires after 10 cycles is ≈3500 mAh g −1 , which is four times that of Si micrometer particles (≈800 mAh g −1 ). [10][11][12][13][14][15][16][17][18][19][20][21] For example, the capacity of Si nanowires after 10 cycles is ≈3500 mAh g −1 , which is four times that of Si micrometer particles (≈800 mAh g −1 ).…”