We report an in situ alloying strategy for obtaining homogeneous (Bi,Sb) alloy nanoparticles from (Bi,Sb)2S3 nanotubes for the exceptional anode of potassium ion batteries (KIBs). The operando X-ray diffraction results, along with transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings, successfully reveal the phase evolution of this material, which is (Bi,Sb)2S3 → (Bi,Sb) → K­(Bi,Sb) → K3(Bi,Sb) during the initial discharge and K3(Bi,Sb) → K­(Bi,Sb) → (Bi,Sb) in the charging process. The in situ alloying strategy produces a synergistic effect and brings an outstanding electrochemical performance. It achieves ultrahigh discharge capacities of 611 mAh g–1 at 100 mA g–1 (0.135C) and 300 mAh g–1 at 1000 mA g–1 (1.35C) and retains a capacity as high as 353 mAh g–1 after 1000 cycles at 500 mA g–1 (0.675C) with a Coulombic efficiency close to 100%. In addition, the KIBs full cell, which is composed of this anode and a perylenetetracarboxylic dianhydride cathode, reaches an initial discharge capacity as high as 276 mAh g–1 at 500 mA g–1 and maintains 207 mAh g–1 after 100 cycles.

In addition, in-depth understanding of the nature of electrode material is an essential step in the development of electrode materials. [21][22][23][24] The electrode materials play a vital role in the battery. [25,26] During the deintercalation and conversion reactions, the electrode material is subjected to various physical and chemical changes, such as phase transitions and electrochemical reorganization. [27] These series of physical and chemical changes will affect the electrochemical performance. [28] Therefore, it is necessary to optimize and improve the electrochemical performance of the battery by studying the reaction mechanism. [29][30][31][32] Transition metal dichalcogenides (TMDs) have gained comprehensive attention in the field of energy storage due to their unique electrochemical properties, high electrical conductivity, and high capacity. [33][34][35][36][37][38][39][40] The inadequacies are also obvious, including volume expansion, agglomeration, low ion-diffusion coefficient, and side reaction during discharge/charge, resulting in the rapid decay of capacity. [41] To achieve high performance rechargeable batteries, it is important to understand the physical and chemical changes in electrode materials during the charge/discharge process. Researchers have made remarkable progress. [42] Usually TMDs involve a multi-step reaction mechanism as anode material for lithium ion batteries and sodium ion batteries (intercalation and conversion). [43][44][45] However, the physical and chemical changes in these TMDs in the potassium ion batteries are still not clear, which hinders the design and development of electrode materials. Therefore, exploring the reaction mechanism of metal selenide not only allows us to understand the relationship between TMDs and K + , but also achieve a long life cycle that would be a breakthrough for large-scale energy storage equipment.Herein, we successfully synthesized carbon-coated FeSe 2 clusters via a solvothermal method. The FeSe 2 clusters are well wrapped by the carbon layer, which improves electron conductivity and alleviates volume expansion. Benefiting from the unique structure, FeSe 2 /N-C exhibit ultra-stable cycle performance with a reversible capacity of up to 170 mAh g −1 at a high current of 2000 mA g −1 , which remains ≈158 mAh g −1 after 2000 cycles. The capacity retention is close to 100%. The electrodes also show remarkable rate performance. Furthermore, first-principles calculations, in situ X-ray diffraction, and ex situ transmission electron microscopy (in situ XRD and ex-TEM) Potassium ion hybrid capacitors have great potential for large-scale energy devices, because of the high power density and low cost. However, their practical applications are hindered by their low energy density, as well as electrolyte decomposition and collector corrosion at high potential in potassium bis(fluoro-sulfonyl)imide-based electrolyte. Therefore, anode materials with high capacity, a suitable voltage platform, and stability become a key factor. Here, N-doping carbon-co...

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Large-scale low-cost preparation methods for high quality graphene are critical for advancing graphene-based applications in energy storage, and beyond.

A eutectic electrolyte strategy is proposed for zinc-iodine battery. Both the reasonable solvated structure and suppressed generation of I3− as an intermediate product achieve the high reversible I−/I0 conversion.

Graphite as an anode for the potassium ion battery (PIBs) has the merits of lowc ost and potentially high energy density,w hile suffering from limited cycle time and inferior stability.H erein we,u sing ac oncentrated electrolyte,d emonstrate that formation of ar obust inorganic-richp assivation layer on the graphite anode could resolve these problems. Consequently,the PIBs with graphite anode could operate for over 2000 cycles (running time of over 17 months) with negligible capacity decay, and had ah igh area capacity over 7.36 mAh cm À2 with ah igh mass loading of 28.56 mg cm À2 . These unprecedented performances of graphite are comparable to that of traditional lithium-ion batteries,and may promote the rapidly development of high performance PIBs.

Graphene is of great significance in energy storage devices. However, a graphene-based electrode is difficult to use in direct applications due to the large surface area and flexibility, which leads to the excessive consumption of electrolyte, low Coulombic efficiency, and electrode shedding behaviors. Herein, a special crystal carbon@graphene microsphere (CCGM) composite was successfully synthesized. The scalable carbonaceous microsphere composite displays a small specific surface area and a superior structure stability. As a potassium ion battery electrode in a half-cell, CCGM delivers an initial capacity of 297.89 mAh g −1 with a high Coulombic efficiency of about 99%. It achieves an excellent cyclic stability with no capacity loss after 1250 cycles at the low current density of 100 mA g −1 with a long performing period of more than one year. As the cathode for an aluminum battery, a reversible specific capacity of 99.1 mAh g −1 at 1000 mA g −1 is obtained. CCGM delivers a long cycle performance of about 10 000 cycles at 4000 mA g −1 with a capacity retention of nearly 100%. Our design provides a fresh thought for the improvement of graphene-based materials, and it will greatly facilitate the application of graphene in the field of energy storage.

Rechargeable zinc-ion batteries employing metallic zinc anode and aqueous electrolytes have received significant attention since they are safe, cost-effective, and environmentally friendly. Thanks to the introduction of phosphate radical, the...