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Lithium-sulfur (Li-S) batteries are considered promising candidates for next-generation advanced energy storage systems due to their high theoretical capacity, low cost and environmental friendliness. However, the severe shuttle effect and weak redox reaction severely restrict the practical application of Li-S batteries. Herein, a functional catalytic material of tin disulfide on porous carbon spheres (SnS

An Li2B4O7 cladded carbon nanofiber membrane has been designed as an interlayer for Li–S batteries. Due to abundant electronic deficiencies [BO3] in Li2B4O7, the enhanced electrochemical performance of Li–S batteries was achieved.

The modified separator with sandwich structure can efficiently promote electrochemical reactions, block the shuttle effect, and inhibit the lithium dendrite by excellent electrical conductivity, strong physical barrier and chemical adsorption.

Lithium-sulfur (Li-S) batteries have attracted tremendous attention as promising next-generation energy-storage systems due to their high specific capacity and high specific energy. However, the shuttle of polysulfides and the growth of Li dendrites severely obstruct the practical applications of these batteries. In this work, a functional separator is designed and fabricated in which nano-calcium fluoride (CaF2) particles are embedded in reduced graphene oxide (rGO) and bladed on a PP separator. The density functional theory (DFT) calculations of the adsorption energy and bond length reveal that CaF2 has a satisfying adsorption and catalytic effect on polysulfides (Li2Sn). The factional separator could accelerate homogenous Li+ flow and retard the growth of Li dendrites. In addition, an initial specific capacity of 1504 mAh g-1 at 0.05C is achieved, and it still retains a discharge capacity of 1050 mAh g-1 over 100 cycles at 0.2C. Moreover, the capacity decay rate is only 0.06% per cycle over 420 cycles at a high current density of 0.5 C. The excellent performance could be attributed to the CaF2@rGO modified separator not only accelerating the transmission of electrons but also effectively inhibiting the shuttling of polysulfides. This work provides a better method for attaining practical applications of high-performance lithium-sulfur batteries.

α-Ni(OH)2 is an ideal candidate material for a supercapacitor except for its low conductivity and poor stability. In this work, BO2--intercalated α-NixCo(1-x)(OH)2 is synthesized by a hydrothermal method at a low cost. The Co dopant can decrease the charge-transfer resistance and enhance the cyclic stability. The special unsaturated electronic state of BO2- enhances the bonding with metal ions and attracts water molecules. Thus, the BO2- ions support the hydroxide layers as pillars and create efficient paths for proton transportation, optimizing the utilization of α-Ni(OH)2. The three-dimensional (3D) flowerlike morphology supplies an enormous number of active sites, and r-GO is added to improve the conductivity. As a result, the modified α-Ni(OH)2 exhibits the specific capacitance of 2179, 1592, and 1423 F·g-1 at 1, 20, and 40 A·g-1, respectively, showing improved rate performance. Matching with the commercial activated carbon (AC) as an anode, the asymmetric capacitor delivers an energy density of 40.66 W·h·kg-1 when its power density is 187.06 W·kg-1. Meanwhile, it retains 81.5% capacitance of the initial cycle at 5 A·g-1 after 3000 cycles. With conductivity enhanced and structure stabilized, the modified α-Ni(OH)2 confronts broader fields of application.

Although the lithium–sulfur battery has been developed for many years, how to restrain the intrinsic polysulfide shuttle is still a hot topic. Recently, it has been found that adding a multifunctio...

High energy density and long cycle life of lithium-sulfur (Li-S) batteries suffer from the shuttle/expansion effect. Sufficient sulfur storage space, local fixation of polysulfides, and outstanding electrical conductivity are crucial for a robust cathode host. Herein, a modified template method is proposed to synthesize a highly regular and uniform nitrogen/oxygen dual-doped honeycomb-like carbon as sulfur host (N/O-HC-S). The unique structure not only offers physical entrapment for polysulfides (LiPSs) but also provides chemical adsorption and catalytic conversion sites of polysulfides. In addition, this structure offers enough space for loading sulfur, and a regular space of nanometer size can effectively prevent sulfur particles from accumulating. As expected, the as-prepared N/O-HC900-S with high areal sulfur loading (7.4 mg cm

Lithium-sulfur (Li-S) batteries have attracted considerable attention owing to their extremely high energy densities. However, the application of Li-S batteries has been limited by low sulfur utilization, poor cycle stability, and low rate capability. Accelerating the rapid transformation of polysulfides is an effective approach for addressing these obstacles. In this study, a defect-rich single-atom catalytic material (Fe-N4/DCS) is designed. The abundantly defective environment is favorable for the uniform dispersion and stable existence of single-atom Fe, which not only improves the utilization of single-atom Fe but also efficiently adsorbs polysulfides and catalyzes the rapid transformation of polysulfides. To fully exploit the catalytic activity, catalytic materials are used to modify the routine separator (Fe-N

α-Ni(OH)

“Turning waste into treasure” is of significance for sustainable development nowadays. Semi-coke in fine particles, abandoned as solid waste, has a less commercial value in the metallurgical industry and also causes environmental contamination. In this research, man-made graphite was prepared by the facile graphitization of semi-coke using silicon as the catalyst at 2300 °C. The obtained sample revealed spherical morphology and a high degree of graphitization with a small specific surface area. Furthermore, as the anode material for lithium-ion batteries, the sample displayed excellent lithium storage properties, delivering high delithiation capacity of 347.06 mA h g−1 at 0.05C, with the capacity even reaching 162.3 mA h g−1 at 3C. An excellent cycle life was displayed with capacity retention of 97.7% at 0.5C after 700 cycles. Generally, SG obtained can serve as an anode material in consideration of the following predominant advantages: (i) a raw material at a lower cost; (ii) the lower charge/discharge plateau voltage after graphitization at 2300 °C; (iii) an ultra-high rate performance and excellent cycle retention at a higher rate; (iv) retention of the spherical structure without retreatment. Also, the one-step heat treatment was easier to conduct and handle. The important advantages of the samples give us a clear direction towards large-scale production.

Similar to MXene, MAB is a group of 2D ceramic/metallic boride materials which exhibits unique properties for various applications. However, these 2D sheets tend to stack and therefore lose their active surface area and functions. Herein, an amorphous cobalt nickel boride (Co–Ni–B) nanocomposite is prepared with a combination of 2D sheets and nanoparticles in the center to avoid agglomeration. This unique structure holds the 2D nano-sheets with massive surface area which contains numerous catalytic active sites. This nanocomposite is prepared as an electrocatalyst for borohydride electrooxidation reaction (BOR). It shows outstanding catalytic activity through improving the kinetic parameters of BH4− oxidation, owing to abundant ultrathin 2D structure on the surface, which provide free interspace and electroactive sites for charge/mass transport. The anode catalyst led to a 209 mW/cm2 maximum power density with high open circuit potential of 1.06 V at room temperature in a miniature direct borohydride fuel cell (DBFC). It also showed a great longevity of up to 45 h at an output power density of 64 mW/cm2, which is higher than the Co–B, Ni–B and PtRu/C. The cost reduction and prospective scale-up production of the Co–Ni–B catalyst are also addressed.

Metal-free carbon nanomaterials doped with heteroatoms are deemed as promising alternatives to platinum for O2 reduction in fuel cell and metal-air batteries. To boost the catalytic activity, construction of nanoporous structured carbons with exposed active sites and improved ions/gas mass transport capability is the main research objective. However, controlled preparation of carbon materials with uniform morphology and tunable nanopore sizes is still a great challenge. Herein, a novel furfuryl alcohol-derived, N, O-codoped nanoporous carbon (FANC) with honeycomb-like structure is reported, which possesses high uniformity and controllable pore sizes. Four FANCs with various pore sizes were carefully prepared and their electrocatalytic activity toward oxygen reduction reaction (ORR) were systematically investigated. Among the four FANCs, the one with a pore size of 12 nm (FANC-12) receives the best ORR performance, which is close to that of commercial Pt/C in alkaline electrolyte. A high power density of 174.1 mW cm-2 was obtained with FANC-12 as cathode catalyst in a flexible solid-state zinc-air battery. Calculation by density functional theory reveals the possible structure of this novel N, O-codoped carbon material and also demonstrates that pyridinic N species are the active sites, which is consistent with the experimental result.

The synthetic graphite with higher specific capacity and superior cyclic lifespan is prepared by high temperature graphitization of anthracite coupled with effective catalyst. In the process of graphitization, the thermodynamically unstable carbon atoms orderly convert from disordered structure to graphite crystal structure by thermal activation. However, it is necessary for the graphitization process at high temperature above 2800 °C. The slow reaction speed, low conversion rate, and unmanageable temperature result in a low graphitization degree. Also, B2O3 as catalyst is beneficial to the directional growth of the aromatic layer in graphite structure, which reduces the cross-linking of the aromatic layer and enhances its coplanarity, as well as reduces energy barrier of graphitization and accelerates the formation of graphite phase. When served as anode material for lithium-ion batteries, the material delivers high delithiation capacity of 369 mA h g−1 with first coulomb efficiency (FCE) of 85.3% at 0.05C and even 160 mA h g−1 at 3C. Moreover, at the current density of 0.5 C, the initial capacity still maintains more than 300 mA h g−1 accompanied with almost 98% capacity after 500 cycles. Often, more than 80% of capacity retention at 2 C enables it more competitive and attractive in the fields of anode materials. By matching the graphite as anode and commercial LiFePO4 as cathode, a full battery is assembled, which still remains the capacity of 93% after nearly 400 cycles, showing cyclic stability of the material. The research provides a direction for the mass production of graphite with coal.

Porous activated carbon material is successfully prepared with anthracite through KOH activation. The obtained activated carbon delivers a large specific surface area of 3550.7 m2 g−1 with existence of porous structure. The KOH activation introduces numerous hydroxyl groups on the surface of carbon material, improving the wettability of carbon. As electrode for supercapacitor, the material delivers the high specific capacity of 433 F g−1 at the current density of 0.5 A g−1 and it maintains 230 F g−1 even current density reaches up to 50 A g−1. Especially, as electrode for symmetric capacitor, the porous activated carbon exhibits a high specific capacitance of 280 F g−1 and energy density of 38.9 Wh kg−1 at 0.5 A g−1. The material also displays superior cyclic stability without distinct decay in capacity after 30000 cycles. The porous activated carbon material derived from coal, which embodies characteristics of capacitance behavior, may broaden the horizon of electrode materials and provide application prospect for specialized hybrid supercapacitor applications.