The limited resources and uneven distribution of lithium stimulate strong motivation to develop new rechargeable batteries that use alternative charge carriers. Potassium-ion batteries (PIBs) are at the top of the list of alternatives because of the abundant raw materials and relatively high energy density, fast ion transport kinetics in the electrolyte, and low cost. However, several challenges still hinder the development of PIBs, such as low reversible capacity, poor rate performance, and inferior cycling stability. Research on the cathode is currently focused on developing materials with high energy density and cycling stability, mainly including layered transition metal oxides, polyanion compounds, organic compounds, etc. Anodes based on intercalation reactions, conversion reactions, and alloying with potassium are currently under development, and promising results have been published. This review comprehensively summarizes the research effort to date on the electrode material optimization (e.g., crystals, morphology, reaction mechanisms, and interface control), the synthesis methods, and the full cell fabrication for PIBs to enhance the electrochemical potassium storage and provide a platform for further development in this battery system.

Potassium-ion batteries: outlook on present and future technologies

With the ever-increasing adaption of large-scale energy storage systems and electric devices, the energy storage capability of batteries and supercapacitors has faced increased demand and challenges. The electrodes of these devices have experienced radical change with the introduction of nano-scale materials. As new generation materials, heterostructure materials have attracted increasing attention due to their unique interfaces, robust architectures, and synergistic effects, and thus, the ability to enhance the energy/power outputs as well as the lifespan of batteries. In this review, the recent progress in heterostructure from energy storage fields is summarized. Specifically, the fundamental natures of heterostructures, including charge redistribution, built-in electric field, and associated energy storage mechanisms, are summarized and discussed in detail. Furthermore, various synthesis routes for heterostructures in energy storage fields are roundly reviewed, and their advantages and drawbacks are analyzed. The superiorities and current achievements of heterostructure materials in lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), lithium-sulfur batteries (Li-S batteries), supercapacitors, and other energy storage devices are discussed. Finally, the authors conclude with the current challenges and perspectives of the heterostructure materials for the fields of energy storage.

Emerging of Heterostructure Materials in Energy Storage: A Review.

MnO2 cathode materials with the improved stability via nitrogen doping for aqueous zinc-ion batteries

ZnSe is regarded as a promising anode material for energy storage due to its high theoretical capacity and environment friendliness. Nevertheless, it is still a significant challenge to obtain superior electrode materials with stable performance owing to the serious volume change and aggregation upon cycling. Herein, a willow-leaf-like nitrogen-doped carbon-coated ZnSe (ZnSe@NC) composite synthesized through facile solvothermal and subsequent selenization process is beneficial to expose more active sites and facilitate the fast electron/ion transmission. These merits significantly enhance the electrochemical performances of ZnSe@NC for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The obtained ZnSe@NC exhibits outstanding rate performance (440.3 mAh g-1 at 0.1 A g-1 and 144.4 mAh g-1 at 10 A g-1 ) and ultralong cycle stability (242.2 mAh g-1 at 8.0 A g-1 even after 3200 cycles) for SIBs. It is noted that 106.5 mAh g-1 can be retained after 550 cycles and 71.4 mAh g-1 is still remained after 1500 cycles at 200 mA g-1 when applied as anode for PIBs, indicating good cycle stability of the electrode. The possible electrochemical mechanism and the ionic diffusion kinetics of the ZnSe@NC are investigated using ex situ X-ray diffraction, high-resolution transmission electron microscopy, and a series of electrochemical analyses.

Willow-Leaf-Like ZnSe@N-Doped Carbon Nanoarchitecture as a Stable and High-Performance Anode Material for Sodium-Ion and Potassium-Ion Batteries

Metallic selenides have been widely investigated as promising electrode materials for metal-ion batteries based on their relatively high theoretical capacity. However, rapid capacity decay and structural collapse resulting from the larger-sized Na+ /K+ greatly hamper their application. Herein, a bimetallic selenide (MoSe2 /CoSe2 ) encapsulated in nitrogen, sulfur-codoped hollow carbon nanospheres interconnected reduced graphene oxide nanosheets (rGO@MCSe) are successfully designed as advanced anode materials for Na/K-ion batteries. As expected, the significant pseudocapacitive charge storage behavior substantially contributes to superior rate capability. Specifically, it achieves a high reversible specific capacity of 311 mAh g-1 at 10 A g-1 in NIBs and 310 mAh g-1 at 5 A g-1 in KIBs. A combination of ex situ X-ray diffraction, Raman spectroscopy, and transmission electron microscopy tests reveals the phase transition of rGO@MCSe in NIBs/KIBs. Unexpectedly, they show quite different Na+ /K+ insertion/extraction reaction mechanisms for both cells, maybe due to more sluggish K+ diffusion kinetics than that of Na+ . More significantly, it shows excellent energy storage properties in Na/K-ion full cells when coupled with Na3 V2 (PO4 )2 O2 F and PTCDA@450 °C cathodes. This work offers an advanced electrode construction guidance for the development of high-performance energy storage devices.

Construction of Bimetallic Selenides Encapsulated in Nitrogen/Sulfur Co-Doped Hollow Carbon Nanospheres for High-Performance Sodium/Potassium-Ion Half/Full Batteries

Titanium Oxide-Confined Manganese Oxide for One-Step Electrocatalytic Preparation of 2,5-Furandicarboxylic Acid in Acidic Media

A Novel Method to Prepare Flexible 3D NiO Nanosheets Electrodes for Alkaline Rechargeable Ni−Zn Batteries

The invention discloses a ship shaft sealing static ring material and a preparation method thereof. The preparation method comprises the following steps of soaking a treated long composite fiber in aglue solution, the glue solution composed of packing, thermosetting resin and organic solvent, after semi-drying, winding and weaving forming are carried out, then carrying out drying, hot pressing, annealing, machining, finally obtain the ship shaft sealing static ring material. Compared with a traditional static ring, the ship shaft sealing static ring material and the preparation method has more advantages, and is quite outstanding in the designability of the structure, excellent in lubricating and abrasion resistance and mechanical properties, good in manufacturability. According to the ship shaft sealing static ring material and the preparation method, the performances of the strength, the water absorption expansion rate, the friction resistance of the final static ring material are improved, and the method can be used for high-efficiency and large-scale stable production.

Ship shaft sealing static ring material and preparation method thereof

The invention discloses a static ring material for ship shaft system end surface sealing and a preparation method of the static ring material. The static ring material is prepared from the raw materials of composite fibers, a soaking solution and a viscous glue solution; the composite fibers are prepared from core material fibers and cladding layer fibers according to the mass ratio of 1:(9 to 49); the soaking solution is prepared from thermosetting resin, a lubricant and an organic solvent which are mixed; and the viscous glue solution is prepared from thermosetting resin, a filler and an organic solvent. The static ring material is good in mechanical property, resistant to friction and abrasion, low in friction coefficient, high in water absorption rate, low in water absorption expansionrate, high in working temperature, simple in preparation process and low in cost; and a static ring can be used for a military ship shaft sealing system, and can also be used for shaft sealing systems of civil ships, ocean platforms, deep sea navigators and the like.

Zhou Kai

Papers

Construction of Bimetallic Selenides Encapsulated in Nitrogen/Sulfur Co-Doped Hollow Carbon Nanospheres for High-Performance Sodium/Potassium-Ion Half/Full Batteries

Titanium Oxide-Confined Manganese Oxide for One-Step Electrocatalytic Preparation of 2,5-Furandicarboxylic Acid in Acidic Media

A Novel Method to Prepare Flexible 3D NiO Nanosheets Electrodes for Alkaline Rechargeable Ni−Zn Batteries

Ship shaft sealing static ring material and preparation method thereof

Static ring material for ship shaft system end surface sealing and preparation method of static ring material