VS4 has an one-dimensional chain structure with the chain spacing of 0.583 nm, which is greater than Na+ ion radius of 0.102 nm. Moreover, its theoretical sodium storage capacity is 1 196 mA·h/g, making it one of the most promising anode materials for sodium storage. However, the volume of the electrode material expands and contracts dramatically during repeated cycling, resulting in collapse of the structure, poor cycling stability and capacity decay, and severely affecting the practical application of VS4. In this paper, VS4 microspheres (approximately 1 μm in diameter) with a high stability were constructed for the unique three-dimensional microsphere structure to alleviate the volume expansion, improve the cycling stability and the electrochemical reaction kinetics. This microsphere structured material as an anode material for sodium ion batteries exhibits a superior rate performance (i.e., 372 mA·h/g@2.0 A/g and 297 mA·h/g@5.0 A/g) and a long-cycle life (i.e., stable cycling for 100 times at 5.0 A/g).

To solve the problems of low electrical conductivity and poor stability of V2O3 as an anode electrode of secondary batteries, sulfur (S) doped V2O3/C nanowires were prepared via electrostatic spinning and sulfuration treatment technology. The structure, chemical composition, and energy storage properties were characterized. The results show that the S doped V2O3/C nanowire as an anode electrode for lithium ion batteries has a discharge specific capacity of 538 mA·h/g at a current density of 0.1 A/g after 50 cycles, and the discharge specific capacity at 2 A/g after 600 cycles can still maintain 288 mA·h/g. The specific capacity of sodium ion batteries with S-doped V2O3/C nanofiber as an anode electrode is 233 mA·h/g at 0.1 A/g after 100 cycles.

Different amounts of LiCoO2 from waste lithium-ion batteries were dissolved in nitrite acid and the recovered Li and Co were used to modify Na0.67Fe0.5Mn0.5O2 cathode by a sol-gel method. Based on the results by X-ray diffraction, Li+/Co3+ ions were doped into Na0.67Fe0.5Mn0.5O2, with the smaller lattice parameters. The results by X-ray photoelectron spectroscopy show that the doping of Li/Co ions leads to the conversion of Mn3+ ions to Mn4+ ions, resulting in the less Jahn teller effect. The results by electrochemical tests indicate that the cycle stability and rate performance of the modified Na0.67Fe0.5Mn0.5O2 improve due to LiCoO2 modification. The sample with x of 0.105 (i.e., Na0.53Li0.105Co0.105(Fe0.5Mn0.5)0.79O2) possesses a capacity retention of 67% after 150 cycles at a current density of 1 C, and a specific capacity is 30 mA·h/g at 5 C.

To improve the rate capability of hard carbon (HC), the corresponding hierarchical porous morphology was designed and the metal organic framework (ZIF-8) was selected as a precursor, and the hierarchical pore structure was adjusted via the addition of BiCl3. The results show that the synthesized hierarchical structure of HC electrodes can effectively improve the diffusion of Na ions. The synthesized hierarchical porous hard carbon can achieve a high reversible capacity of 225 mA·h/g and 177 mA·h/g at different currents of 2 A/g and 5 A/g, respectively, based on the optimized micro-and macro-pores. Furthermore, a relationship between the hierarchical porous structure (with micro-and macro-pores) and the sodium storage process was discussed. It is indicated that the micro-pores prefer to facilitate the sodium-ion diffusion in a plateau region, while the meso-pores prefer to provide more defect sites to enhance the adsorption of sodium ions, consequently improving the sodium storage capacity.

Boron (B)-doped LiNi0.6Co0.2Mn0.2O2 cathode materials were prepared by oxalate co-precipitation and subsequent heat treatment. The effects of doping with different boron sources (B2O3, H3BO3 and LiBO2) on the morphology, structure and electrochemical properties of the materials were investigated. The X-ray diffracation and Rietveld refinement revealed that the B element was successfully doped into the material lattice. The electrochemical performance characterization showed that the doping effect of B2O3 was the best, with excellent rate performance (the specific discharge capacity was 145.1 mA·h/g at 5 C) and long-term cycle stability (the capacity retention ratio was 84.5% after 300 cycles at 1 C). The enhanced electrochemical performance is attributed to the fact that boron doping effectively reduces the surface residual lithium compound, enhances the structural stability of the material, effectively inhibits the voltage drop and improve the polarization phenomenon, and reduces the charge transfer resistance, thus inhibiting the capacity decay and achieving excellent electrochemical performance.

The composite polymer solid electrolytes (CPE) were prepared by a solution-casting and hot-pressing method. Na-β-Al2O3 and g-C3N4 particles were incorporated into a polyoxyethylene and polycaprolactone blended polymer electrolyte to obtain the CPE. The microstructures, chemical and electrochemical properties of the composite electrolytes were investigated. The composite electrolyte with a high conductivity at room temperature, a high voltage stability, and a dendrite suppression capability is obtained via optimizing the mass ratio of each component, especially g-C3N4. At 50 ℃, the symmetric cells with metallic Na electrodes exhibit a good long-term cycling stability at a current density of 0.1 mA/cm2. The all-solid-state cells with Na3V2(PO4)3@C positive electrode and Na/C composite negative electrode maintain a specific capacity of about 107 mA· h/g at 0.2 C.

Na11Sn2PS12 solid electrolytes were synthesized by a high-temperature quenching method, and the structures as well as electrochemical performance were investigated. A Na11Sn2PS12 phase with a certain amount of impurity can be obtained in quenching process. The content of impurity phase in the quenching precursors annealed at 430 ℃decreases and the room-temperature ionic conductivity enhances from 0.34×10-4 S/cm to 6.26×10-4 S/cm. In addition, a prepared Na11Sn2PS12 possesses a low activation energy of 0.27 eV and an electronic conductivity of 2.25×10-8 S/cm, and an electrochemistry stability window between 0.8 V and 2.8 V. Also, Na11Sn2PS12 is used in all-solid-state sodium batteries, showing good electrochemical performances.

A hammer-like Co3O4 was firstly prepared by using metal-organic framework-74 as a template, and then compounded with elemental Ag to fabricate a highly active catalyst with an improved electronic conductivity. The Li-O2 battery with this prepared catalyst has a specific discharge capacity of 13 945 mA·h/g at a current density of 100 mA/g. Even at a high current density of 1 000 mA/g, the battery can still maintain a specific discharge capacity of 4 476.3 mA·h/g, indicating that it has an excellent rate performance. Also, the cycle performance is greatly improved. For the limited specific capacity of 1 000 mA·h/g at the current density of 500 mA/g, the battery with Ag/Co3O4 catalyst can be used for 195 cycles, while that with Co3O4 catalyst can be used for only 42 cycles.

Lithium-rich cathode materials are regarded as one of the most promising candidates for high energy lithium-ion batteries delivering reversible capacity of 300 mA·h/g, which are better than the commercial cathode materials. However, some drawbacks of lithium-rich cathode materials (i.e., low initial Coulombic efficiency, voltage decay and capacity decay) affect the practical application. In this review, we represented recent studies on two types lithium-rich cathode materials, i.e. lithium-rich Mn-based cathode materials and lithium-rich cation disordered cathode materials, introduced the crystal structure, cation redox and anion redox mechanisms of these lithium-rich cathode materials in detail, discussed the drawbacks of the materials and some sources of these drawbacks, and summarized the performance improvement, thus providing the theoretical guidance and technical support for future research of lithium-rich cathode materials.

The safety and cycling stability issues of lithium-ion battery as a prevalent electrochemical energy storage device have attracted much recent attention. Lithium plating on the anode material is a common failure reason of lithium-ion battery, thus becoming a hot research area in industry. However, some common detection methods are not applied for the batteries due to the closed packed structure. Therefore, the detection of lithium plating becomes a problem in the lithium-ion battery industry. To address this issue, this review represented recent progress on lithium plating detection methods via the following aspects, i.e., building special in-situ cells, prediction according to external properties, and measurement of new physical parameters. In addition, the future developing trend was also prospected.

Lithium-ion capacitor has structure of consisting of the battery-type anode and capacitor-type cathode, thus having a enabling high energy density and a high power density. This capacitor expected to become the next generation of new energy storage devices. The kinetic mismatch between the Faradaic battery-type anode and capacitive cathode is a great challenge for lithium-ion capacitors. Therefore, researchers have developed a variety of high-rate lithium-ion battery materials. Among these materials, vanadium-based materials are considered as ideal anode materials for lithium-ion capacitor due to their low cost, large specific capacity, and superior rate performance. This review summarized recent work on the optimization strategies of several vanadium-based anode materials, i.e. Li3VO4, VN and Li3V2O5. In addition, the future directions in the application of vanadium-based anode materials for lithium-ion capacitor were also proposed.

Solid-state lithium batteries with solid electrolytes are expected to enhance the battery safety and energy density as one of the most promising next-generation batteries. Among various solid-state electrolytes, sulfide solid electrolyte is considered as promising candidate due to its ultra-high ionic conductivity. However, its large-scale production is restricted due to its fragility and difficulty in processing, which affects its application in solid-state batteries. Recent work indicates that the flexibility of solid electrolytes can be realized via introducing flexible polymers or supporting frameworks in solid electrolytes membranes, constituting a solution to the embrittlement challenge in large-scale and thin-film electrolyte preparations. Therefore, developing flexible solid electrolytes is one of the important strategies to promote the industrialization of solid-state batteries. This review introduced the physical/chemical properties and development of sulfide solid electrolytes, summarized the related research work on polymer self-supporting method and flexible skeleton-supporting method in the flexibility of solid electrolytes, and discussed the technical characteristics and advantages/disadvantages of wet/dry processes in the flexible sulfide solid electrolyte preparation, respectively. In addition, the future development aspects were also given to promote the practical application of solid-state lithium batteries.

Compared with conventional organic liquid electrolyte batteries, all-solid-state batteries for next-generation energy storage have attracted recent attention due to their advantages of high safety, high energy density and long cycle life. Organic-inorganic composite solid electrolytes as the most promising electrolyte systems have some advantages of inorganic solid electrolytes with a high strength, a high stability and a high ionic conductivity, and some advantages of solid polymer electrolytes for softness and easy processing as well. This review introduced the fundamentals of Li-ion solid-state electrolytes, and discussed some problems of organic-inorganic composite solid electrolytes (i.e., ionic conductivity, solid-solid interface, electrochemical window and compatibility between organic and inorganic compounds) and optimization strategies. In addition, some challenges and future development on organic-inorganic composite solid electrolytes were also described.

Organic sulfides are recognized as the most promising cathode materials for lithium-sulfur batteries due to their high capacities, abundant resources and adjustable structures. Organic sulfides have a variety of superior features with respect to the diversity of structural designs, superior lithium storage properties and reaction mechanisms. In this review, recent development on organic sulfides in lithium sulfur batteries was represented, the latest progress of researches on small molecule polysulfides, polysulfides and vulcanized polymers was described, and their structure characteristics and electrochemical mechanisms were illustrated. In addition, the relationship between electrochemical performance of organic sulfides and their structure design as well as functional groups was also summarized. The future prospect of organic sulfides was given for next generation energy storage systems.

Sodium-based layered oxides are a reasearch hotspot due to thier high specific capacity and high ionic conductivity. Different ordering superstructures in these materilas, including Na+/vacancy ordering in Na layer, charge ordering and transition metal ordering in transition metal layer, greatly affect the phase transition process, voltage profile and ion diffusion coefficient, etc.. The characteristics of three types of ordering superstructures were introduced, and the effects of ionic interaction, Fermi level and ionic radius on the ordering superstructures were also discussed. Meanwhile, this review summarized some work on the disordering structures and predicted the promising design directions to supress the ordering structures, for providing a guidance for the structural design of high-performance electrode materials.

Sodium vanadium fluorophosphate (Na3V2(PO4)2F3) is considered as one of the most promising candidates for high-voltage Na-ion batteries cathodes due to the merits of high theoretical specific capacity, high energy density, high output voltage and rapid ion diffusion. However, the sluggish electron transfer kinetics and tremendous structural stress during repeated electrochemical processes restrict the further development and application. In this review, we presented recent progress on the development of Na3V2(PO4)2F3, i.e., the synthetic methods and modification strategies (micro-nano structure fabrication, carbon coating, element doping and battery composition optimization), and also gave the corresponding future outlook.

Energy storage materials are a key to the development of electrochemical energy storage technologies for meeting the higher requestor of novel paradigms in energy revolution. In recent years, high-entropy materials are developed as electrochemical energy storage materials based on the high entropy aspect as an emerging strategy of material design. In this review, high-entropy materials used in lithium ion battery, sodium ion battery and supercapacitor were represented. First, the basic concepts of high-entropy materials were briefly introduced, including the definition of high entropy and related effects. The structure and performance of high-entropy materials used as electrochemical energy storage materialswere comprehensively summarized. Some challenges arising from the development of high-entropy electrochemical energy storage materials were discussed. This review could provide a reference for rationally designing high-entropy electrode materials towards advanced energy storage and conversion.

Compared with the conventional analysis methods for the porous electrode, this paper represents some methods for single particle analysis in battery research, i.e., microeletrode contacting method, single particle collision method, microfluidic analysis method and spectral analysis method. In the single particle analysis methods. some intrinsic properties of the battery materials can be obtained by analyzing directly in single particle scale, thus clarifying the electrochemical reaction mechanism of the material.

Metallic phase molybdenum disulfide (1T-MoS2), as one of the most studied transition metal dichalcogenides (TMDs) materials, has attracted recent attention due to its special structure, abundant active sites, and other outstanding properties. 1T-MoS2 has a wide range of applications in catalysis, sensors, batteries, and supercapacitors. Recent work on the construction and photocatalytic application of 1T-MoS2 and its composites is comprehensively summarized. The basic information of 1T-MoS2 is briefly introduced. Recent advances on the preparation of 1T-MoS2 and its composite are represented. The applications of 1T-MoS2 and its composites in photocatalysis are summarized. In addition, some prospects for the preparation and application of 1T-MoS2 based material are also given.

FexMo1-xS2 with an expanded interlayer spacing of 0.75 nm was prepared via a simple solvothermal method. The larger interlayer spacing enhances the rate of Na+ diffusion during initial cycle. FexMo1-xS2 as an anode for sodium ion batteries exhibits a high capacity of 285 mA·h/g at 0.1 A/g after 100 cycles and an excellent rate capability of 178 mA·h/g at 5 A/g. The fresh and cycled electrodes were characterized by in-situ X-ray photoelectric spectroscopy and transmission electronic microscopy to investigate electrochemical reaction mechanism of FexMo1-xS2 during cycling. The results indicate that the irreversible conversion reaction of FexMo1-xS2 with Na+ results in the formation of main products of Fe-Mo alloy and S.

A multiphysics-coupling model of solid oxide fuel cell (SOFC) was proposed via a software named COMSOL Multiphysics for the establishment of coupled fields of electrochemical-gas, flow-matter and transfer-temperature. The inhomogeneous temperature distribution obtained from the numerical analysis was applied to the corresponding model build by ABAQUS as a thermal load, and the creep damage subroutine developed based on the Wen-Tu creep ductile depletion model was used to analyze the creep damage of SOFC. The creep damage behavior of SOFC was investigated and the creep crack propagation was predicted. The results show that the creep deformation and damage of SOFC components firstly increase and then remain unchanged. The lower connector is the first to reach the critical damage value, which is the potential dangerous area and is the most likely to failure. After 50 000 h, two creep damages occur in SOFC. The maximum crack is 1.6 mm as the non-penetrating crack that occurs at the junction of 1.1 mm in the air inlet of the lower connector and the cathode material. Compared with the overall structure size, the smaller crack will not cause gas leakage, thus meeting the requirement of commercial safe operation for 40 000 h.

High-entropy double perovskite SmBa(Mn0.2Fe0.2Co0.2Ni0.2Cu0.2)2O5+δ (HE-SBC) as a cathode material was prepared by a modified Pechini method, and the performance of HE-SBC with 10% (in mole fraction) Gd2O3-doped CeO2 (GDC) (HE-SBC-GDC) was optimized. The results show that the thermal expansion of Co ions caused by the change of valence state can be reduced due to the formation of high-entropy at B-site, thereby reducing the thermal expansion coefficient of SBC. The polarization impedance (Rp) of the HE-SBC symmetrical cell with yttria-stabilized zirconia (YSZ) as an electrolyte is 1.04 Ω·cm2 at 800 ℃ and the maximum power density and Rp of the anode-supported single cell are 683.53 mW/cm2 and 0.46 Ω·cm2, respectively. Furthermore, the catalytic activity of HE-SBC is improved by the addition of GDC［m(HE-SBC):m(GDC)=7:3］ due to the enlarged three-phase interface. The polarization resistance of HE-SBC-GDC composite cathode symmetric cell is only 0.09 Ω·cm2 at 800 ℃ and the maximum power density and Rp of the anode-supported single cell are 838.66 mW/cm2 and 0.12 Ω·cm2, respectively.

Fluidized catalytic cracking (FCC) catalyst was prepared by a hot acid combined with modified kaolinite as a support material to further explore the influence of modification on the catalytic performance of FCC catalyst. After modification by hot acid binding, kaolinite produces weak B-acid and L-acid sites, and its specific surface area increases from 21.4 m2/g to 44.6 m2/g. Compared with the kaolinite-based FCC catalyst, the performance of the modified kaolinite-based FCC catalyst is significantly improved. The catalytic oil conversion is increased by 1.97%, the heavy oil yield is decreased by 1.62%, and the total liquid yield is increased by 1.54%.

A series of expanded vermiculites with a high expansion ratio were prepared with a vermiculite from Xinjiang, China as raw material by an intercalation microwave method and an intercalation calcination method, respectively. The phase composition and morphology of the products were characterized by X-ray diffraction and scanning electron microscopy, and the cation exchange capacity and methylene blue (MB) adsorption capacity of the expanded vermiculite prepared by the two different methods were analyzed. The results show that there is a significant difference in the expansion ratios of expanded vermiculite prepared by the two methods, and the expansion ratio of calcined expanded vermiculite (BCV) is 0.4 times greater than that of microwave expanded vermiculite (WCV). For adsorption in a methylene blue solution with a concentration of 300 mg/L, the calcined expanded vermiculite has a poor adsorption capacity for MB, while the microwave expanded vermiculite has a good adsorption performance for MB due to its higher cation exchange capacity with an adsorption capacity of 391.26 mg/g.

Granular Y molecular sieve loaded with iron nanoparticles with cation exchange performance was synthesized for simultaneous removal of Cu(Ⅱ) and Cr(Ⅵ) from aqueous solution. The results show that the adsorption capacity of Cu(Ⅱ) increases from 46.6 mg/g to 67.6 mg/g, and the adsorption capacity of Cr(Ⅵ) is 13.2 mg/g when using granular Y molecular sieve loaded with iron nanoparticles. The removal of Cr(Ⅵ) by the loaded material is improved due to the coexistence of Cu(Ⅱ). The removal mechanism of Cu(Ⅱ) by the loaded material involves the cation exchange of Y molecular sieve and the reduction of Fe(0). The removal of Cr(Ⅵ) is mainly attributed to the reduction of Fe(0), and the reductive products of Cu(Ⅱ) can promote the removal of Cr(Ⅵ) by the loaded material.

Platinum (Pt) was encapsulated in ZSM-5 by an one-step hydrothermal method for dehydrogenation of propane to prepare propylene (PDH). The catalysts were characterized by X-ray diffraction, specific surface area measurement, H2-pluse, scanning electron microscopy and transmission electron microscopy. Under the optimal reaction conditions, the propane conversion and propylene selectivity are 48% and 57%. In addition, the catalytic system can also resist the toxic effect of DBT, and the propane conversion and propylene selectivity are not reduced with DBT containing a catalytic system.

Graphene oxide (GO) composite nanofiltration membranes (GO-EDA/Al2O3 membrane) cross-linked by ethylenediamine (EDA) were fabricated on dopamine (PDA) modified alumina ceramic membranes. The covalent bonds enhance the interlayer and interface stability of the as-prepared membranes. A method that can simply adjust the layer spacing of GO composite membranes was proposed. The number of hydroxyl groups inside the GO composite membranes can be changed through varying the drying temperature, thus affecting the pure water permeation and salt rejection of the GO composite membranes. The results show that the thickness of the GO composite membranes fabricated at the drying temperature of 40 ℃ is 50-120 nm. The pure water permeance and the rejection towards Na2SO4 solution are 34 L/(m2·h·MPa) and 87.8%, respectively. The GO composite membranes still remain an excellent stability and a high rejection rate after being immersed in pure water for 680 h.

To improve the low-temperature oxidation resistance of MoSi2, a core-shell structured MoSi2@SiO2 was prepared by a direct preoxidation method, and the preoxidation conditions, as well as the structure and the low-temperature oxidation resistance of MoSi2@SiO2 composite, were investigated. Results show that the core-shell structured MoSi2@SiO2 can be obtained under preoxidation at 800 ℃ for 1 h. The obtained SiO2 shell is amorphous which is formed due to the non-selective oxidation of MoSi2 and the evaporation of the oxidation product MoO3. The oxidation mass gain rate of MoSi2@SiO2 is <1.6% after isothermal cyclic oxidation at 400-700 ℃ for 12 h.