Antimony (Sb)-based anode materials have recently aroused great attention in potassium-ion batteries (KIBs), because of their high theoretical capacities and suitable potassium inserting potentials. ...Nevertheless, because of large volumetric expansion and severe pulverization during potassiation/depotassiation, the performance of Sb-based anode materials is poor in KIBs. Herein, a composite nanosheet with bismuth–antimony alloy nanoparticles embedded in a porous carbon matrix (BiSb@C) is fabricated by a facile freeze-drying and pyrolysis method. The introduction of carbon and bismuth effectively suppress the stress/strain originated from the volume change during charge/discharge process. Excellent electrochemical performance is achieved as a KIB anode, which delivers a high reversible capacity of 320 mA h g–1 after 600 cycles at 500 mA g–1. In addition, full KIBs by coupling with Prussian Blue cathode deliver a high capacity of 396 mA h g–1 and maintain 360 mA h g–1 after 70 cycles. Importantly, the operando X-ray diffraction investigation reveals a reversible potassiation/depotassiation reaction mechanism of (Bi,Sb) ↔ K(Bi,Sb) ↔ K3(Bi,Sb) for the BiSb@C composite. Our findings not only propose a reasonable design of high-performance alloy-based anodes in KIBs but also promote the practical use of KIBs in large-scale energy storage.
To tackle the issue of the poor rate capability of graphite anodes for potassium‐ion batteries (KIBs), nitrogen‐doped carbon nanotubes (NCNTs) with an edge‐open layer‐alignment structure were ...synthesized using a simple and scalable approach of pyrolyzing cobalt‐containing metal–organic frameworks. The unique structure enables a facile and fast intercalation of K ions. As anodes of KIBs, the NCNTs demonstrated an improved rate capability by a high capacity retention of 102 mA h g−1 at a high current density of 2000 mA g−1 and a good stability without evident capacity loss over 500 cycles at 2000 mA g−1. Our findings can help to develop highperformance anode materials for potassium‐ion batteries as large‐scale and low‐cost energy‐storage systems.
MOFs for KIBs: To tackle the issue of the poor rate capability of graphite anodes for potassium‐ion batteries (KIBs), nitrogen‐doped carbon nanotubes (NCNTs) with an edge‐open layer‐alignment structure are synthesized using a simple and scalable approach of pyrolyzing cobalt‐containing metal– organic frameworks.
A layered structure Ni-based MOF was synthesized and, for the first time, was used as the electrode material for a supercapacitor. It exhibited large specific capacitance, high rate capability and ...cycling stability. Capacitances of 1127 and 668 F g −1 can be achieved at rates of 0.5 and 10 A g −1 , respectively. At the same time, over 90% performance was retained after 3000 cycles. These excellent electrochemical properties may be related to the intrinsic characteristics of Ni-based MOF materials.
Red phosphorus (P) has been recognized as a promising storage material for Li and Na. However, it has not been reported for K storage and the reaction mechanism remains unknown. Herein, a novel ...nanocomposite anode material is designed and synthesized by anchoring red P nanoparticles on a 3D carbon nanosheet framework for K‐ion batteries (KIBs). The red P@CN composite demonstrates a superior electrochemical performance with a high reversible capacity of 655 mA h g−1 at 100 mA g−1 and a good rate capability remaining 323.7 mA h g−1 at 2000 mA g−1, which outperform reported anode materials for KIBs. The transmission electron microscopy and theoretical calculation results suggest a one‐electron reaction mechanism ofP + K+ + e−→ KP, corresponding to a theoretical capacity of 843 mA h g−1,which is the highest value for anode materials investigated for KIBs. The study not only sheds light on the rational design of high performance red P anodes for KIBs but also offers a fundamental understanding of the potassium storage mechanism of red P.
A red phosphorous nanoparticle@carbon nanosheet composite is developed for potassium‐ion battery anodes and demonstrates a high reversible capacity of 655 mA h g−1 and outstanding rate capability. A one‐electron reaction mechanism of P + K+ + e− → KP is proposed on the basis of experimental and theoretical thermodynamics studies, corresponding to a theoretical capacity of 843 mA h g−1 for red phosphorous.
Hard carbons (HCs) are the most promising candidate anode materials for emerging Na‐ion batteries (NIBs). HCs are composed of misaligned graphene sheets with plentiful nanopores and defects, ...imparting a complex correlation between its structure and sodium‐storage behavior. The currently debated mechanism of Na+‐ion insertion in HCs hinders the development of high‐performance NIBs. In this article, ingenious and reliable strategies are used to elaborate the correlation between the structure and electrochemical performance and further illuminate the sodium‐storage mechanism in HCs. First, filling sulfur into the micropores of HCs can remove the low‐voltage plateau, providing solid evidence for its association with the pore‐filling mechanism. Along with the decreased concentration of defects/heteroatoms at higher treatment temperature, the reduced sloping capacity confirms the adsorption mechanism in the sloping region. Finally, the similar sodium‐insertion behaviors of HCs with ether‐based and ester‐based electrolytes indicate that no Na+ ions intercalate between the graphene layers. The determined adsorption‐pore‐filling mechanism encourages the design of more efficient HC anode materials with high capacity for high‐energy NIBs.
The sodium‐storage mechanism in hard carbons is elaborated using ingenious strategies. The elimination of the low‐voltage plateau by infusing sulfur into the micropores and the similarity in voltage profiles and specific capacities with ether‐based and ester‐based electrolytes verify the pore‐filling mechanism in the plateau region. This will encourage the design of more efficient hard carbon anode materials.
Lithium–sulfur batteries are regarded as one of the most promising candidates for next‐generation rechargeable batteries. However, the practical application of lithium–sulfur (Li–S) batteries is ...seriously impeded by the notorious shuttling of soluble polysulfide intermediates, inducing a low utilization of active materials, severe self‐discharge, and thus a poor cycling life, which is particularly severe in high‐sulfur‐loading cathodes. Herein, a polysulfide‐immobilizing polymer is reported to address the shuttling issues. A natural polymer of Gum Arabic (GA) with precise oxygen‐containing functional groups that can induce a strong binding interaction toward lithium polysulfides is deposited onto a conductive support of a carbon nanofiber (CNF) film as a polysulfide shielding interlayer. The as‐obtained CNF–GA composite interlayer can achieve an outstanding performance of a high specific capacity of 880 mA h g−1 and a maintained specific capacity of 827 mA h g−1 after 250 cycles under a sulfur loading of 1.1 mg cm−2. More importantly, high reversible areal capacities of 4.77 and 10.8 mA h cm−2 can be obtained at high sulfur loadings of 6 and even 12 mg cm−2, respectively. The results offer a facile and promising approach to develop viable lithium–sulfur batteries with high sulfur loading and high reversible capacities.
A polysulfide‐immobilizing polymer shield is designed by depositing a natural polymer of Gum Arabic (GA) onto high‐conductivity carbon nanofiber (CNF) films as interlayers of Li–S batteries, which not only provides a large active surface and strong chemisorption for immobilizing soluble polysulfides but also ensures a good contact between the CNFs and GA, thus effectively reusing the adsorbed active materials.
Large-scale energy storage technologies are in high demand for effective utilization of intermittent electricity generations and efficient electric power transmission. The feasibility of lithium-ion ...batteries for large-scale energy storage is under debate due to the scarcity and uneven distribution of lithium resources in the Earth's crust. Therefore, there arises tremendous interest in pursuing alternative energy storage systems based on earth-abundant materials. Recently, non-aqueous potassium-ion batteries (KIBs) are emerging as a promising energy storage system due to the abundance of potassium and the encouraging battery performance. Here, the recent research progress in non-aqueous KIBs is summarized, including electrode materials, electrolytes, battery architectures and fundamental electrochemical processes. The challenges and future research opportunities are also briefly discussed.
The recent research progress in non-aqueous potassium-ion batteries is summarized and the challenges and future research opportunities are briefly discussed.
p‐Benzoquinone (BQ) is a promising cathode material for lithium‐ion batteries (LIBs) due to its high theoretical specific capacity and voltage. However, it suffers from a serious dissolution problem ...in organic electrolytes, leading to poor electrochemical performance. Herein, two BQ‐derived molecules with a near‐plane structure and relative large skeleton: 1,4‐bis(p‐benzoquinonyl)benzene (BBQB) and 1,3,5‐tris(p‐benzoquinonyl)benzene (TBQB) are designed and synthesized. They show greatly decreased solubility as a result of strong intermolecular interactions. As cathode materials for LIBs, they exhibit high carbonyl utilizations of 100% with high initial capacities of 367 and 397 mAh g−1, respectively. Especially, BBQB with better planarity presents remarkably improved cyclability, retaining a high capacity of 306 mAh g−1 after 100 cycles. The cycling stability of BBQB surpasses all reported BQ‐derived small molecules and most polymers. This work provides a new molecular structure design strategy to suppress the dissolution of organic electrode materials for achieving high performance rechargeable batteries.
An effective molecular design strategy is developed to suppress the dissolution of benzoquinone‐derived organic electrode materials. Two novel benzoquinone‐derived molecules with near‐plane structure and relatively large skeleton are synthesized to increase the π–π stacking, which show greatly decreased solubility and enhanced electrochemical performance.
Organic cathode materials have attracted extensive attention because of their diverse structures, facile synthesis, and environmental friendliness. However, they often suffer from insufficient ...cycling stability caused by the dissolution problem, poor rate performance, and low voltages. An in situ electropolymerization method was developed to stabilize and enhance organic cathodes for lithium batteries. 4,4′,4′′‐Tris(carbazol‐9‐yl)‐triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high‐voltage redox‐active centers. The electropolymerized TCTA electrodes demonstrated excellent electrochemical performance with a high discharge voltage of 3.95 V, ultrafast rate capability of 20 A g−1, and a long cycle life of 5000 cycles. Our findings provide a new strategy to address the dissolution issue and they explore the molecular design of organic electrode materials for use in rechargeable batteries.
An in situ electropolymerization method was developed to enhance the performance of organic cathodes. 4,4′,4′′‐Tris(carbazol‐9‐yl)‐triphenylamine (TCTA) was employed because carbazole groups can be polymerized under an electric field and they may serve as high‐voltage redox‐active centers. Ultrafast rate performance (20 A g−1), long cycle life (5000 cycles), and high voltage (3.95 V) were demonstrated.
The construction of anode materials for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) with a high energy and a long lifespan is significant and still challenging. Here, ...sulfur-defective vanadium sulfide/carbon fiber composites (D-V5S8/CNFs) are designed and fabricated by a facile electrospinning method, followed by sulfuration treatment. The unique architecture, in which V5S8 nanoparticles are confined inside the carbon fiber, provides a short-range channel and abundant adsorption sites for ion storage. Moreover, enlarged interlayer spacings could also alleviate the volume changes, and offer small vdW interactions and ionic diffusion resistance to store more Na and K ions reversibly and simultaneously. The DFT calculations further demonstrate that sulfur defects can effectively facilitate the adsorption behavior of Na+ and K+ and offer low energy barriers for ion intercalation. Taking advantage of the functional integration of these merits, the D-V5S8/CNF anode exhibits excellent storage performance and long-term cycling stability. It reveals a high capacity of 462 mA h g−1 at a current density of 0.2 A g−1 in SIBs, while it is 350 mA h g−1 at 0.1 A g−1 in PIBs, as well as admirable long-term cycling characteristics (190 mA h g−1/17 000 cycles/5 A g−1 for SIBs and 165 mA h g−1/3000 cycles/1 A g−1 for PIBs). Practically, full SIBs upon pairing with a Na3V2(PO4)3 cathode also exhibit superior performance.
