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Lithium–sulfur batteries with high energy density are considered to be one of the most promising candidates for the next‐generation energy storage devices. Electrolyte as the medium for Li+ transportation between the electrodes, also plays a crucial role in inhibiting the dissolution and diffusion of lithium polysulfides in Li–S batteries. The working mechanism of Li–S batteries in different electrolytes is classified into "solid‐liquid‐solid" and "solid‐solid" conversions. Under the "solid‐liquid‐solid" conversion, Li–S batteries would inevitably face the challenges such as "shuttle effect" that lead to poor cycle performance, and under the "solid‐solid" conversion, they would face interface mismatch that limits the utilization of sulfur with low energy density, while both conversion mechanisms cause uncontrollable Li dendrites on anode. According to the conversion mechanism, electrolytes can be divided into ether‐based, ionic liquid‐based, gel polymer electrolytes, and polymer‐based solid‐state electrolytes with "solid‐liquid‐solid" conversion, as well as carbonate‐based electrolytes and oxide/sulfide‐based solid‐state electrolytes with "solid‐solid" conversion. Based on the conversion mechanism of active materials in different electrolytes, the current status on the strategies from multiple perspectives are summarized to improve the electrochemical performance, with the hope to provide a comprehensive guideline toward the development of suitable electrolytes for Li–S batteries. [ABSTRACT FROM AUTHOR]

• The 3D hierarchically porous carbon were synthesized via in-situ template and KOH activation from pectin. • The activation temperature and the addition of urea can adjust the content of heteroatoms and the pore structure. • The in-situ hard template can adjust the micropore/mesopores ratio. • The high specific surface area and its suitable micropore/mesopores ratio are helpful to promote charge storage and ion transfer. Pectin as a functional biopolymer has been successfully exploited to produce N/O co-doped 3D carbon architecture with hierarchical pores. A simple and novel in-situ template combining with KOH activation method is utilized to prepare porous carbon using calcium acetate as the template source and urea as a dopant. The in-situ CaCO 3 template, activation temperature and urea additive have a significant influence on the morphology, pore structure and performance of porous carbon. The high specific surface area of NHPC-700 (2928 m2 g −1) and its suitable micropore/mesopores ratio are helpful to promote specific capacitance and rate performance. The NHPC-700 possesses the high specific capacitance of 338 F g −1 at 1 A g −1 and the excellent capacitance retention of 83% from 1 A g −1 to 50 A g −1. Furthermore, the NHPC-700 symmetric supercapacitor shows an energy density of 22.4 Wh kg−1 at 880 W kg−1 in 1 M Na 2 SO 4. The efficient use of pectin to synthesize functionalized hierarchical porous carbon materials has a broad development prospect. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• The petal-like NiFeCo-S@NiFeCo-TH ultrathin nanosheets were in situ synthesized on NIF. • The Co2+ exchange reaction plays a vital role in fabricating the ultrathin nanosheets. • The NiFeCo-S@NiFeCo-TH displays rich active sites and short mass diffusion path. • The self-supporting NiFeCo-S@NiFeCo-TH nanosheets show a high energy density. Rationally designing self-supporting heterogeneous nanostructured electrode materials is an effective strategy to enhance electrochemical performance and mechanical strength for asymmetric supercapacitors. Herein, we report a facile synthesis of the self-supporting petal-like NiFeCo-S (Sulfides) @NiFeCo-TH (Ternary Hydroxides) heterogeneous ultrathin nanosheets on nickel iron foam (NIF) using an innovative electro-oxidation, sulfuration and controllable Co2+ exchange process. Petal-like NiFeCo-S@NiFeCo-TH ultrathin nanosheets with the thickness of only 1.8 nm consist of Ni 2 S 3 , FeS, CoNi 2 S 4 , FeCoS 2 and NiFeCo hydroxides nanocrystallines to provide rich interfaces. The unique nanostructured NiFeCo-S@NiFeCo-TH lamellar hybrid delivers the high areal capacity (mass capacity) of 973 µAh cm−2 (174 mAh g−1) at a current density of 10 mA cm−2 and excellent rate capability of 68.3% at a high current density of 100 mA cm−2. More importantly, the assembled NiFeCo-S@NiFeCo-TH/NIF//AC all-solid-state ASC device exhibits a high energy density of 56.3 Wh kg−1 at a power density of 543 W kg−1 and the outstanding cycling stability of 90.1% capacity retention after 4000 charge-discharge cycles. This synthesis strategy exhibits wide application prospect in fabrication of the self-supporting transition metal nanostructured electrodes for energy storage and conversion. [ABSTRACT FROM AUTHOR]

• A host material of sulfur with graphene-supported organic molecules is fabricated for Li–S batteries. • The organic molecule can anchor lithium polysulfides by forming a "Li···N" interaction. • The composite sulfur cathode presents improved electrochemical performance. Lithium–sulfur (Li–S) batteries with high theoretical energy density have been regarded as promising energy storage devices. However, the sluggish redox kinetics and shuttle effect of lithium polysulfides of sulfur cathodes remain obstacles to their development, especially with high sulfur content. Herein, we introduce the organic molecule of 3-amino-1,2,4-triazole (AT) on graphene (G) through π–π interactions as a sulfur host material to address the shuttle effect of lithium polysulfides. The molecular fragment of = N–C N– in AT as the active site can effectively anchor polysulfides existing as neutral molecules and free radicals in the electrolyte via "Li···N" interaction. Combined with the fast electron transport facilitated by the graphene, the redox kinetics of polysulfides is promoted. Thus, the electrochemical performance of Li–S batteries can be remarkably improved. The S/G-AT electrode displays excellent electrochemical performance in terms of a high initial capacity (1411 mAh/g at 0.2C), long-term cycling stability (799 mAh/g after 450 cycles at 1C), and superior rate performance (817 mAh/g at 10C). This study helps to utilize functional organic molecules for fabricating high-performance cathode materials for Li–S batteries. [ABSTRACT FROM AUTHOR]

• 3D model of indirect shell-tube reactor coupling physical–chemical-thermal process. • Interaction of reactive transport and heat transfer process of Ca(OH) 2 dehydration. • When HTF inlet velocity increases to 40 m⋅s−1, the reaction time reduced by 46.6%. • Adding tubes in by-pass region improves energy storage amount and reaction rate. • Five possible schemes are proposed to improve the reactor low η store. The Ca(OH) 2 /CaO system is a promising candidate for thermochemical energy storage because of its high energy density, low cost and negligible heat loss. Coupling mechanisms of multiple physiochemical processes still need further investigation and the system performance should be further improved. In this work, for the first time, a three-dimensional numerical model is developed to study the thermochemical energy storage process by Ca(OH) 2 dehydration reaction in a shell-tube reactor. The turbulent heat transfer fluid flow in the shell side, and the steam flow, heat transfer and dehydration reaction in the tube side are comprehensively taken into account. Effects of operation conditions and reactor geometry parameters on the dehydration process are also investigated in detail. Five indicators are proposed to comprehensively evaluate the reactor performance, including reaction time, energy storage density, heat exchange power, heat exchange efficiency and energy storage efficiency. The results reveal that higher inlet temperature and inlet velocity of heat transfer fluid can enhance the heat transfer and accelerate the reaction. Lower porosity, although increases the energy storage density, leads to higher flow resistance and impedes the reaction. With deep understanding of the physiochemical processes, 16 more tubes are properly added in the by-pass flow region, leading to shorter reaction time and higher energy storage amount. The low values of heat exchange efficiency and energy storage efficiency reveal that the input heat cannot be efficiently transferred to the tube side. To improve the energy conversion performance of reactor, additional schemes are discussed including regenerative HTF, optimization of reactor geometry, increase of reactant thermal conductivity, reducing tube-side flow resistance and extending HTF residence time. The numerical model and simulation results in the present work could be helpful for optimizing the shell-tube Ca(OH) 2 /CaO reactor and improving the thermochemical energy storage performance. [ABSTRACT FROM AUTHOR]

Mesoporous NiCo 2 S 4 materials with high specific surface area and suitable mesopores display excellent supercapacitor performance due to rich electroactive sites and short diffusion paths. Here, the mesoporous NiCo 2 S 4 microaggregates composed of nanoparticles are first successfully prepared by a simple anion exchange method to puff NiCo 2 O 4 cubes. The NiCo 2 S 4 microaggregates possess rich mesoporous structure with high surface area of 63.79 m2 g−1 and suitable pore size distribution centered at 6.1 nm. The NiCo 2 S 4 microaggregates deliver high specific capacity of 249 mAh g−1 (at 1 A g−1) and good rate capability of 56.2% capacity retention from 1 to 20 A g−1. The fabricated NiCo 2 S 4 //AC ACS exhibits a prominent energy density of 47.9 Wh kg−1 at a power density of 783 W kg−1 and immensely distinguished cycling stability (98.8% retention of the initial capacitance after 4000 cycles). These remarkable performances can corroborate superiority of the mesoporous structure for improving supercapacitor electrode properties. Image 1 • The mesoporous NiCo 2 S 4 were first successfully prepared by anion exchange method. • The NiCo 2 S 4 microaggregates possess rich mesoporous structure. • The NiCo 2 S 4 shows good supercapacitor performance and topping cycling stability. [ABSTRACT FROM AUTHOR]

• A new electro-oxidation method was explored to synthesize lamellar NiOOH. • The multi-dimensional Co 1.29 Ni 1.71 O 4 @CoNi 2 S 4 networks were transformed from NF. • The nanosheets possess large interface and efficient conductive network. • The nanosheet network displays high capacitance and outstanding rate capability. Sandwich nanostructured networks constructed by cross-linked Co 1.29 Ni 1.71 O 4 @CoNi 2 S 4 heterogeneous nanosheets in-situ generated on nickel foam are first synthesized through an innovative Fast-Repeated-Charging/Discharging (FRCD) electro-oxidation and subsequent ion-exchange. This multi-dimensional nanostructure assembled by 0D Co 1.29 Ni 1.71 O 4 nanoparticles with the size of 10 ∼ 20 nm, 2D ultra-thin CoNi 2 S 4 nanosheets with the thickness of about 1.5 nm and 3D interconnected nanosheets can endow the electrode material with abundant active sites, sufficient electrolyte-electrode interfaces, fast ion transport path, high conductivity and excellent structural stability to achieve remarkable electrochemical performance. Benefiting from this intriguing structural and componental advantages, the Co 1.29 Ni 1.71 O 4 @CoNi 2 S 4 delivers ultra-high area specific capacity of 916 µAh cm−2, the area specific capacitance of 8386 mF cm−2 and the specific capacitance of 2045 F g−1 at 2 mA cm−2, and topping rate capability of 50.9% for capacity (91.1% for capacitance) from 2 to 200 mA cm−2. The fabricated Co 1.29 Ni 1.71 O 4 @CoNi 2 S 4 /NF//AC ACS exhibits a prominent energy density of 47 Wh kg−1 at 527 W kg−1 and possesses immensely distinguished cycling stability of 85.3% retention after 8000 cycles. Subsequently, the assembled Co 1.29 Ni 1.71 O 4 @CoNi 2 S 4 /NF//AC all-solid-state ASC device with a voltage window of 1.6 V delivers a high energy density of 44.3 Wh kg−1 at a power density of 496 W kg−1. This construction of advanced nanostructures will shed hoping light on designing high performance electrode materials for supercapacitors, batteries, water splitting and N 2 reduction reaction. [ABSTRACT FROM AUTHOR]