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Developing electrode materials with high tap density, low cost, and superior performance poses a formidable challenge in electrochemistry. The impressive performance exhibited by most electrodes comes at the expense of tap density and cost, severely limiting their practical applications. Here, combining computational and experimental results, an approach for the electrode materials with high tap density and rich heterostructure (Cu2S/Na2Sn) from cheap copper smelting slag enabled by an electrochemical process is proposed, reducing the diffusion energy barrier from 0.82 to 0.28 eV for Na+, as well as delivering an impressively high tap density of 3.32 g cm−3. Furthermore, the electrochemical activation process that irreversibly generates more stable Cu2S and Na2Sn after the first charge progress of parent materials is also revealed by in/ex situ analytical techniques. As expected, assembled sodium ion capacitors (SICs) achieve high energy density (74.4 Wh kg−1) at high power density (20 000 W kg−1) with outstanding capacity retention of 81.5% after 10 000 cycles, delivering over 76% of its energy density in 13.4 s, which surpasses the performance achieved by state‐of‐the‐art SICs. This work not only provides novel insights into irreversibly conversion‐type anodes but also introduces a method for efficient value‐added utilization of smelting slag. [ABSTRACT FROM AUTHOR]

Nowadays sodium‐based energy storage systems (Na‐based ESSs) have been widely researched as it possesses the possibility to replace traditional energy storage media to become next generation energy storage system. However, due to the irreversible loss of sodium ions in the first cycle, development of Na‐based ESSs is limited. Presodiation, as a strategy of adding excess sodium ions to the system in advance, accomplishes the enhancement of electrochemical performance. In this minireview, different presodiation strategies applied in sodium‐based energy storage systems will be summarized in detail, their functions and corresponding mechanisms will be discussed as well. Furthermore, the current novel application of presodiation method in other aspects of Na‐based ESSs will be mentioned additionally. At last, in the view of present research status of presodiation, issues that can be mitigated are put forward and guidelines are given on how to deliberate in‐depth presodiation technology in the future, dedicating to promote the further development of Na‐based ESSs. [ABSTRACT FROM AUTHOR]

In the past 10 years, preeminent achievements and outstanding progress have been achieved on sodium‐ion capacitors (SICs). Early work on SICs focussed more on the electrochemical performance. While it is easy to confirm which specific electrodes exhibit excellent properties, it is difficult to understand the mechanisms which are most promising for the next generation of SICs. From the early research in supercapacitors iterations to the present well‐developed Na‐ion batteries, the evolution of the controversial pseudocapacitive mechanism for SICs has been full of breakthroughs and back tracing steps. Moreover, as the research has progressed and the interests have changed, different emphases on the different subdisciplines (cell configurations, flexible devices, and presodiation technologies) have increased. In this review, first, the electric double layer mechanism, battery‐type mechanism, and the controversial pseudocapacitance mechanism are systematically analyzed and compared. Subsequently, mechanism‐oriented SICs cell configurations with different cathode and anode mechanisms are discussed. Moreover, the characteristics and features of electrode materials in different SICs cell configurations are summarized. Finally, key technologies and possible future developments are discussed. This review summarizes SICs from a broad and macro perspective from mechanisms to cell configurations, from cathodes to anodes, and from history to future, and offers a deep understanding of SICs devices. [ABSTRACT FROM AUTHOR]

Nonaqueous sodium‐ion capacitors (SICs), as a new type of energy storage cell, can potentially achieve high energy‐power densities, long cycling lifespan, and low cost in one device. Given this, developing suitable carbonaceous electrode materials for carbon‐based SICs is of great significance. Unlike lithium‐ion batteries (LIBs) and lithium‐ion capacitors (LICs) that have been successfully commercialized, SICs are still at an early stage. As a result, rational electrode material design for SICs is needed to meet the requirements of electrochemical energy‐storage systems. Carbon materials with a wide range of sources and low toxicity deliver significant potential applications in high‐performance SICs, whether as positive or negative parts. Various carbonaceous electrode materials have been explored and investigated for developing SICs over the past years. This Review firstly introduces the classical and widely used configurations and corresponding energy‐storage mechanism in detail for SICs. Then, recent progress on carbonaceous electrode materials, including cathode and anode materials, are summarized. Finally, the challenges and some suggestions on the future development of carbon‐based SICs are proposed. [ABSTRACT FROM AUTHOR]

Prelithiation/presodiation techniques are regarded as indispensable procedures in electrochemical energy storage (EES) systems, which can effectively compensate irreversible capacity loss, raise working voltage, and increase Li+/Na+ concentration in the electrolyte. Various prelithiation/presodiation methods have been successfully exploited and a revolutionary impact has been achieved through the utilization of prelithiation/presodiation techniques. It is well acknowledged that different prelithiation/presodiation strategies possess their own specific mechanisms, which play vital roles in the advancement of EES systems. However, there has rarely been systematical reviews about the concept and progress of prelithiation/presodiation techniques. Hence, in this review various prelithiation/presodiation approaches are comprehensively analyzed and summarized, and in‐depth prelithiation/presodiation behaviors and other innovative applications (including optimization of separators, amelioration of binders, regeneration of spent batteries) are discussed in detail. Finally, suggested future directions of prelithiation/presodiation techniques are proposed and it is expected that these prelithiation/presodiation techniques could provide guidance for construction of advanced EES systems and propel the commercialization process with a focus on safety considerations. [ABSTRACT FROM AUTHOR]

Sodium‐ion capacitors (SICs) have triggered considerable attention due to potential high energy densities under high power densities. The presodiation process of anodes is very important for the construction of high‐performance SICs; however, in the current presodiation method, metallic sodium is utilized as the presodiation agent through the assembling/disassembling of half‐cells, which is very complicated and dangerous, greatly hindering the development of SICs. Herein, a novel voltage‐induced high‐efficient in situ presodiation approach is successfully realized by introducing organic sodium salts as the sodium sources into the cathode. Moreover, the irreversible electrochemical characteristic of organic sodium salts triggered by high voltage could provide sufficient sodium sources for presodiation without any negative effects for further operation of SICs. Significantly, the diversified anodes like carbon and TiO2 are successfully presodiated and the corresponding SICs manifest excellent electrochemical performances. This rational strategy is anticipated to shed light on a potential avenue for greatly simplifying the assembly process of the SICs, which may largely accelerate the commercialization process of SICs. [ABSTRACT FROM AUTHOR]

Heteroatom‐doping is an effective approach to modify the microstructure of carbon‐based materials toward enhanced electrochemical energy storage performance. Nevertheless, it is a great challenge to obtain a specific heteroatom‐doped carbon material with hierarchical structure as a general doping strategy is missing. Herein, carbon materials doped with P, S and both of them are designed and precisely prepared through in‐situ polymerization. Used as anode for sodium‐ion batteries, the best performing material displays a high specific capacity of 368.6 mAh g−1 at a current density of 0.1 A g−1 after 100 cycles. A high capacity of 159.8 mAh g−1 is achieved at a large current density of 5 A g−1. Impressively, this material also delivers robust storage performances for lithium. According to the first‐principles method and detailed experimental data, the expanded interlayer distance and enhanced electronic conductivity of the microcrystalline region can be attributed to C−S and P−C bonds, while the high surface capacitance contribution can be assigned to surface C−S species and highly exposed edges of the microcrystalline region. This work sheds light on a promising method for the exploitation of versatile heteroatom modified hierarchical carbon materials. [ABSTRACT FROM AUTHOR]

Abstract Compared to other energy storage types, capacitive energy-storage serves increasingly significant roles in shortening reversible cycling times and enlarging high power than traditional batteries. It still suffers from the low pseudo-capacitive level and short of electrodes, along with low energy density. Considering the great theoretical capacity, here 1D chain-like Co 3 O 4 is prepared though the thermal oxidation of the self-assembled rod-like Co-precursor. Followed by in-situ polymerization of pyrrole monomer, the Co 3 O 4 were encapsulated in the transparent PPy shell. Particle size-tuning, 1D architecture-altering, conducting PPy introduction could effectively broaden the energy distribution of ions, increase the speed of ions directional transferring and improve the conductivity with protecting electrode materials. As Li-storage anodes, Co 3 O 4 /PPy delivers a stable capacity of 816.6 mAh g−1 at 1.0 A g−1 after 300 cycles. 801.3 mAh g−1 at 5.0 A g−1. The capacity of full-cell still delivers 526 mAh g−1 at 3.0 A g−1 after 50 loops. Supported by detailed kinetic analysis of CV curves, it is confirmed, (1) the nature of Co 3 O 4 approaches to capacitor-like behavior; (2) its electrochemical properties are dominated by capacitive contributions with increased current density as well as cycling. This work provides an in-depth sight on Co 3 O 4 , and further improving its pseudo-capacitive behaviors. Graphical abstract fx1 Highlights • The chain-like Co 3 O 4 was obtained through Kirkendall effect. • The pseudo-capacitive nature of Co 3 O 4 was studied. • Co 3 O 4 /PPy showed the good cycling stability (800 mAh g−1 after 800 cycles). • The capacity of full-cell reached to 532 mAh g−1 at 3.0 A g−1. • The in-depth kinetic analysis was effectively performed. [ABSTRACT FROM AUTHOR]

Recently, the carbonization of metal organic frameworks (MOFs) has become an efficient method to prepare metal‐oxide materials on carbon support, which can provide advantages toward conversion‐type reactions of lithium ion batteries as the size and shape of the materials can be tuned by adjusting the MOF ligands. Formic acid is widely used in MOFs with diverse coordination models, which can further regulate morphologies of the carbonized metal oxides. However, less work is reported on the fabrication of metal oxides with formic acid ligands and their application as electrode materials. Herein, utilizing the self‐assembled MOFs [NH2(CH3)2][FeIIIFeII(HCOO)6] with formic acid ligands as the precursor, a carbon decorated Fe3O4 is successfully prepared, consisting of Fe3O4 nanoparticles with diameters of 40–60 nm and the coated carbon that is stemmed from the organic precursor of formic acid. When used as the electrode materials for lithium‐ion batteries, this composite exhibits good rate capability and stabilized reversible capacity of 1041 mAh g−1 after 50 cycles at 100 mA g−1. These superior properties can be attributed to the synergetic effect of the unique nano/micro structure and uniform dispersion of the conductive carbon provided by this new MOF precursor. Enter the (carbon) matrix: carbon decorated Fe3O4 nanoparticles are successfully designed and synthesized using a MOF precursor. The composite material is applied as anodes in lithium‐ion batteries. The electrodes exhibited good rate capability and stable reversible capacity of 1041 mAh g−1 after 50 cycles at a current density of 100 mA g−1. [ABSTRACT FROM AUTHOR]

Abstract: Hierarchical nanoscale carbons have received wide interest as electrode materials for energy storage and conversion due to their fast mass transfer processes, outstanding electronic conductivity, and high stability. Here, heteroatom (S, P, and N) doped hierarchical vesicular carbon (HHVC) materials with a high surface area up to 867.5 m2 g−1 are successfully prepared using a surface polymerization of hexachloro‐cyclotriphosphazene (HCCP) and 4,4′‐sulfonyldiphenol (BPS) on the ZIF‐8 polyhedrons. Significantly, it is the first time to achieve a controllability of the wall thickness for this unique carbon, ranging from 18 to 52 nm. When utilized as anodes for sodium ion batteries, these novel carbon materials exhibit a high specific capacity of 327.2 mAh g−1 at 100 mA g−1 after 100 cycles, which can be attributed to the expanded interlayer distance and enhanced conductivity derived from the doping of heteroatoms. Importantly, a high capacity of 142.6 mAh g−1 can be obtained even at a high current density of 5 A g−1, assigning to fast ion/electronic transmission processes stemming from the unique hierarchical vesicular structure. This work offers a new route for the fabrication/preparation of multi‐heteroatom doped hierarchical vesicular materials. [ABSTRACT FROM AUTHOR]

Abstract: Different dimensions of carbon materials with various features have captured numerous interests due to their applications on the tremendous fields. Restricted by the raw materials and devices, the controlling of their morphology is a major challenge. Utilizing the catalytic features of the intermediates from the low‐cost salts and polymerization of 0D carbon quantum dots (CQDs), 0D CQDs are expected to self‐assemble into 1/2/3D carbon structures with the assistance of temperature‐induced intermediates (e.g., ZnO, Ni, and Cu) from the salts (ZnCl2, NiCl2, and CuCl). The formation mechanisms are illustrated as follows: 1) the “orient induction” to evoke “vine style” growth mechanism of ZnO; 2) the “dissolution–precipitation” of Ni; and 3) the “surface adsorption self‐limited” of Cu. Subsequently, the degree of graphitization, interlayer distance, and special surface area are investigated in detail. 1D structure from 700 °C as anode displays a high Na‐storage capacity of 301.2 mAh g−1 at 0.1 A g−1 after 200 cycles and 107 mAh g−1 at 5.0 A g−1 after 5000 cycles. Quantitative kinetics analysis confirms the fundamentals of the enhanced rate capacity and the potential region of Na‐insertion/extraction. This elaborate work opens up an avenue toward the design of carbon with multidimensions and in‐depth understanding of their sodium‐storage features. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are regarded as a promising candidate for large-scale energy storage applications, however, its sluggish sodiation kinetics limit high power capabilities. First-principles density functional theory (DFT) calculations demonstrates that the replacement of large anions, within a Co 3 X 4 (X = O, S, Se) complex, can facilitate electron transfer through the reduction of the energy band gap (Eg) and the regulation of structural, electronic and bonding properties of Co-X, suggesting that the substituted Co 3 X 4 in the following order O < S < Se can provide enhanced Na-storage capability. Accordingly, Co 3 X 4 have been successfully designed, in which the selection of anions induces the evolution of microstructure, creating an enhancement of specific surface area with the effective introduction of defects. Note that the similar phys/chemical properties of anions within the Co 3 X 4 possess analogous conversion mechanisms, further confirmed by in-situ XRD. Quantitative kinetics analysis reveals that the levels of the surface-dominated redox behaviors are greatly promoted by the decreased binding energy of Na 2 X (Na 2 O > Na 2 S > Na 2 Se) with the increased active sites, which are paramount for electrochemical properties. The work in this article sheds light on the in-depth understanding of the improved sodium-storage behavior with the advancing VI group anions and provides an effective strategy for the design of high-rate electrode materials for SIBs. [ABSTRACT FROM AUTHOR]

Antimony sulfide (Sb 2 S 3 ) has been shown as a promising candidate for sodium ions batteries, in considering the gravimetric energy density and high theoretical capacity. Hollow-sphere Sb 2 S 3 coated with carbon are successfully designed through Oswald ripening process. The Sb 2 S 3 /C utilized as SIBs anode displays excellent electrochemical properties, delivering a high charge capacity of 693.4 mAh g −1 at 0.2 A g −1 between 0.01 and 3.0 V (vs. Na + /Na). Its reversible capacity can keep 545.6 mAh g −1 , with a retention of ∼80% after 100 cycles. Even the current densities return from 6.4 to 0.2 A g −1 , the Sb 2 S 3 /C still maintains 550.8 mAh g −1 after 70 cycles. Combining the large void space with carbon layer, the advantages are noticed when the increased electrolyte penetration area, improved electronic conductivity and shortened Na + diffusion length are attained concurrently, resulting in the excellent specific capacity and cycling stability. The study provides an effect strategy in improving the electrochemical performances of metal sulfides as anode for SIBs. [ABSTRACT FROM AUTHOR]

The ever-increasing demand of lithium-ion batteries (LIBs) caused by the rapid development of various electronics and electric vehicles will be hindered by the limited lithium resource. Thus sodium-ion batteries (SIBs) have been considered as a promising potential alternative for LIBs owing to the abundant sodium resource and similar electrochemical performances. In recent years, significant achievements regarding anode materials which restricted the development of SIBs in the past decades have been attained. Significantly, the sodium storage feasibility of carbon materials with abundant resource, low cost, nontoxicity and high safety has been confirmed, and extensive investigation have demonstrated that the carbonaceous materials can become promising electrode candidates for SIBs. In this review, the recent progress of the sodium storage performances of carbonaceous materials, including graphite, amorphous carbon, heteroatom-doped carbon, and biomass derived carbon, are presented and the related sodium storage mechanism is also summarized. Additionally, the critical issues, challenges and perspectives are provided to further understand the carbonaceous anode materials. [ABSTRACT FROM AUTHOR]

Hollow-sphere ZnSe is successfully obtained through Ostwald ripening. Carbon nanoparticles are designed and utilized to form a wrapped carbon network as a conductive buffering matrix by subsequent annealing. The ZnSe/C composites, as anode materials for lithium-ion batteries (LIBs), exhibit excellent Li+ storage properties, delivering a high reversible capacity of 573.7 mA h g−1 at 1.0 A g−1 after 800 cycles. Even upon increasing the high current density to 20.0 A g−1, the reversible capacity can achieve 318.8 mA h g−1 after 5000 cycles. The superior rate capability is confirmed through the current density return from 20.0 to 1.0 A g−1, and ZnSe/C composites still recover up to 469 mA h g−1, with a retention of 92%. The enhanced electrochemical performances of ZnSe/C composites are attributed to the unique structure and the introduction of conductive carbon networks, which can improve the Li+ diffusion coefficient in the insertion and extraction process. Furthermore, the interconnected network also alleviates the volume variation during cycling and further enhances the structural stability. [ABSTRACT FROM AUTHOR]

Yolk-like TiO2 are prepared through an asymmetric Ostwald ripening, which is simultaneously doped by nitrogen and wrapped by carbon from core to shell. It presents a high specific surface area (144.9 m2 g−1), well-defined yolk-like structure (600-700 nm), covered with interweaved nanosheets (3-5 nm) and tailored porosity (5-10 nm) configuration. When first utilized as anode material for sodium-ion batteries (SIBs), it delivers a high reversible specific capacity of 242.7 mA h g−1 at 0.5 C and maintains a considerable capacity of 115.9 mA h g−1 especially at rate 20 C. Moreover, the reversible capacity can still reach 200.7 mA h g−1 after 550 cycles with full capacity retention at 1 C. Even cycled at extremely high rate 25 C, the capacity retention of 95.5% after 3000 cycles is acquired. Notably, an ultrahigh initial coulombic efficiency of 59.1% is achieved. The incorporation of nitrogen with narrowing the band gap accompanied with carbon uniformly coating from core to shell make the NC TiO2-Y favor a bulk type conductor, resulting in fast electron transfer, which is beneficial to long-term cycling stability and remarkable rate capability. It is of great significance to improve the energy-storage properties through development of the bulk type conductor as anode materials in SIBs. [ABSTRACT FROM AUTHOR]

3D porous carbon encapsulated SnO 2 nanoparticles composite (SnO 2 -PC) prepared by an efficient in situ methodology was applied as anode for sodium ion batteries (SIBs). It delivered a high reversible specific capacity of 280.1 mAh g −1 after 250 cycles at a current density of 100 mA g −1 , with ultrahigh capacity retention of 91.63%. Notably, it can Exhibit 100 mAh g −1 after 1000 cycles even at a high current density of 1600 mA g −1 . These greatly enhanced electrochemical properties of SnO 2 -PC composite can be attributed to the superior structure that the electrical conductivity of the composite was improved by the porous carbon matrix, moreover, it can serve as a cushion during the process of Na ion insertion/extraction into the composite. Significantly, this kind of in situ synthesis method is portable for other similar composite. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) metal-organic frameworks (MOFs) exhibit great promise as high-energy anode materials for next-generation lithium-ion capacitors (LICs) due to their tunable chemistry and short ion transport paths. Nevertheless, high-throughput production of ultrathin 2D MOFs and energy storage mechanism analysis are still full of challenges. Here, theoretical calculations indicate that partial introduction of Fe in Co sites can enhance interaction of metal centers with water in solvents due to the strong 3d-2p orbital binding energy, which induces ultrathin nanosheets, resulting in exposure of high-density ligand active sites, lower band gap and higher Young modulus during lithium insertion. Greatly, ultrathin 2D Co/Fe-BDC nanosheets are obtained with a bottom-up method and can be scaled up to high-throughput production. In/ex-situ results further reveal highly reversible insertion/extraction reactions accompanied by crystalline to amorphous for Co/Fe-BDC anodes. LICs with optimal Co 4 Fe-BDC anode deliver high energy density (199.7 Wh kg−1) and power density (10,000 W kg−1), together with superior cycle lifespan. This work offers in-depth insights for the high-throughput synthesis and the storage mechanism in 2D MOFs. [Display omitted] • Ultrathin metal-organic frameworks are synthesized by a stirring method with the potential for scale-up production. • The DFT calculations reveal the introduction of Fe induces 2D stuctures and enhances electrochemical kinetics. • In/ex-situ results indicate Co/Fe-BDC shows the insertion/extraction mechanism accompanied by crystalline to amorphous. • The optimal LICs deliver high energy density (199.7 Wh kg−1), power density (10000 W kg−1) and superior cycle lifespan. [ABSTRACT FROM AUTHOR]

Interconnected carbon nanofibers networks (ICNNs) prepared through the carbonization of polypyrrole (PPy) precursor are utilized as conductive pathways and buffer to improve the Na storage performance of antimony (Sb) as anode for sodium-ion batteries (SIBs). The as-obtained Sb/ICNNs composite exhibits excellent cycle stability. The reversible capacity can remain 542.5 mAh g −1 with a high capacity retention of 96.7% after 100 cycles at a current density of 100 mA g −1 . And the superior rate performance is also observed, the reversible capacity can still reach 325 mAh g −1 at a high current density of 3200 mA g −1 . These great electrochemical performances observed above suggest that this type of composite can be a nice option for advanced SIBs anode materials and may be extended to other active materials/ICNNs composite electrode. [ABSTRACT FROM AUTHOR]

Co 2 MnO 4 /Co hydroxide chloride (CMO/CHC) nanocomposite is firstly obtained through an electrochemically alternating voltage methodology for supercapacitor applications. The CMO/CHC electrode materials display a high specific capacitance of 779 F g −1 at 1 A g −1 and an excellent rate behavior (77.5% and 63.6% at 20 and 40 A g −1 compared with 1 A g −1 , respectively). An asymmetric supercapacitor based on CMO/CHC as cathode and activated carbon (AC) as anode presents a maximum energy density of 27.8 Wh kg −1 at power density of 570.9 W kg −1 . [ABSTRACT FROM AUTHOR]

A novel and facile in-situ methodology has been developed to prepare well carbon-coated anatase titanium dioxide (TiO 2 ) nanoparticles. The hydrolysis of tetrabutyl titanate has been effectively controlled in a collosol of N-methyl-2-pyrrolidone dissolved with polyvinylidene fluoride. The as-resulted carbon-dispersed TiO 2 nanoparticles distributed in ranges from 20 to 30 nm in diameter have been obtained with a carbon content of 11.7 wt%. This nanocomposite utilized as anode materials in lithium-ion battery can deliver a high reversible specific capacity of 218 mAh g −1 at the current density of 0.2 C (33.5 mA g −1 ), and still exhibit 100 mAh g −1 at 10 C (1.68 A g −1 ), illustrating notable high-rate performances for the potential application in fast charge/discharge batteries. [ABSTRACT FROM AUTHOR]

Nonoxidative cathodically induced graphene (CIG) here incorporates conductive agents for Li4Ti5O12 (LTO) anode materials. The tailored LTO/CIG composite is fabricated by controlled hydrolysis of tetrabutyl titanate in the presence of nonoxidative defect-free cathodically induced graphene (CIG) and oxalic acid in a mixed solvent of ethanol and water, followed by hydrothermal reaction and a calcination treatment. Due to the introduction of defect-free graphene, the resulting LTO/CIG composite shows an excellent electrical conductivity (1.2 × 10−4 S cm−1) and Li+ diffusion coefficient (1.61 × 10−12 cm2 s−1). As a result, the tuned LTO/CIG composite exhibits outstanding electrochemical performance, including excellent cycling stability (the capacity retention ratios after 500 cycles at 0.5 C is 96.2%) and a remarkable rate capability (162 mAh g−1 at 10C, 126 mAh g−1 at 100 C). A specific energy of 272 Wh kg−1 at power of 136 W kg−1 is observed when cycling against Li-foil. Even during 36 s of charge/discharge, the specific energy of LTO/CIG composite remains at 166 Wh kg−1. [ABSTRACT FROM AUTHOR]

Keywords: batteries; electrochemistry; energy storage; presodiation; sodium EN batteries electrochemistry energy storage presodiation sodium 1 1 1 11/24/21 20211122 NES 211122 B Presodiation, known as b pre-doping of sodium ions, represents the addition of sodium sources to ensure adequate sodium content in the sodium-based energy storage systems. In addition, multiple functions of presodiation are clarified, such as compensating for sodium loss, addressing safety issue, enhancing energy density and so on, aiming to promote the development of Na-based energy storage systems. Batteries, electrochemistry, energy storage, presodiation, sodium. [Extracted from the article]

Room temperature sodium–sulfur batteries have emerged as promising candidate for application in energy storage. However, the electrodes are usually obtained through infusing elemental sulfur into various carbon sources, and the precipitation of insoluble and irreversible sulfide species on the surface of carbon and sodium readily leads to continuous capacity degradation. Here, a novel strategy is demonstrated to prepare a covalent sulfur–carbon complex (SC‐BDSA) with high covalent‐sulfur concentration (40.1%) that relies on SO3H (Benzenedisulfonic acid, BDSA) and SO42− as the sulfur source rather than elemental sulfur. Most of the sulfur is exists in the form of OS/CS bridge‐bonds (short/long‐chain) whose features ensure sufficient interfacial contact and maintain high ionic/electronic conductivities of the sulfur–carbon cathode. Meanwhile, the carbon mesopores resulting from the thermal‐treated salt bath can confine a certain amount of sulfur and localize the diffluent polysulfides. Furthermore, the CSxC bridges can be electrochemically broken at lower potential (<0.6 V vs Na/Na+) and then function as a capacity sponsor. And the R‐SO units can anchor the initially generated Sx2− to form insoluble surface‐bound intermediates. Thus SC‐BDSA exhibits a specific capacity of 696 mAh g−1 at 2500 mA g−1 and excellent cycling stability for 1000 cycles with 0.035% capacity decay per cycle. The covalent sulfur–carbon complex SC‐BDSA (S, 40.1%) with different chain lengths is prepared. The short‐chain bridges can be electrochemically broken at potential <0.6 V (Na/Na+) and then worked together with the long‐chain units as a capacity sponsor. The R‐SO parts anchor Sx2− to form insoluble surface‐bound intermediates, leading to a special capacity of ≈750 mAh g−1 over 200 cycles. [ABSTRACT FROM AUTHOR]

As a result of its high‐energy density, metal–selenides have demanded attention as a potential energy‐storage material. But they suffer from volume expansion, dissolved poly‐selenides and sluggish kinetics. Herein, utilizing' thermal selenization via the Kirkendall effect, microspheres of NiSe2 confined by carbon are successfully obtained from the self‐assembly of Ni‐precursor/PPy. The derived hierarchical hollow architecture increases the active defects for sodium storage, while the existing double N‐doped carbon layers significantly alleviate the volume swelling. As a result, it shows ultrafast rate capability, delivering a stable capacity of 374 mAh g−1, even after 3000 loops at 10.0 A g−1. These remarkable results may be ascribed to the NiOC bonds on the interface of NiSe2 and the carbon film, which leads to the faster transfer of ions, the effective trapping of poly‐selenide, and the highly reversible conversion reaction. The kinetic analysis of cyclic voltammetry (CV) demonstrates that the electrochemical process is mainly dominated by pseudocapacitive behaviors. Supported by the results of electrochemical impedance spectroscopy (EIS), it is confirmed that the solid–electrolyte interface films are reversibly formed/decomposed during cycling. Given this, this elaborate work might open up a potential avenue for the rational design of metal‐sulfur/selenide anodes for advanced battery systems. Hierarchial hollow‐structured NiSe2/N‐C with double carbon films are designed from the self‐assembled clew‐like Ni‐Pr by the Kirkendall effect. And it is found that incorporation of NiOC into the carbon layers enables tailoring of the interfacial traits, inducing the fascinating electrochemical behaviors. This elaborate work might open up a potential avenue for these rational TMDs anodes designs for advanced battery storage systems. [ABSTRACT FROM AUTHOR]

The sodium storage performance of NiS2 suffer from low initial coulombic efficiency and poor cycling stability which are ascribed to the volume expansion and collapse of the structure during the charge/discharge transformation process. Compared with composites, encapsulating NiS2 in carbon framework is more effective in buffering for the volume expansion and enhancing the electronic conductivity of sodium‐ion batteries. In this work, NiS2 decorated with bifunctional carbon (NiS2@C@C), where nickel dimethylglyoxime and polyaniline are employed as the precursor and carbon source, respectively, are obtained. Since the introduced carbon layer suppresses the volume expansion and enhances both the electronic conductivity and charge transfer of Na+, the attained NiS2@C@C displays outstanding sodium storage performance. At a current density of 0.1 A g−1, a high reversible specific capacity of 580.8 mAh g−1 remains even after 100 cycles. The first coulombic efficiency (79.65%) and rate performance (448 mAh g−1 at 1.6 A g−1) of NiS2@C@C are also remarkable. Extraordinarily, the excogitation of NiS2 decorated with bifunctional carbon is also significant for the preparation of similar materials. Through the sulfuration of nickel dimethylglyoxime wrapped with polyaniline, bifunctional carbon decorated NiS2 (NiS2@C@C) is prepared. Benefitting from the ingenious design, the sodium storage performance of NiS2@C@C electrodes is greatly superior to undecorated NiS2 electrodes. This work might supply an effective excogitation for the practical application of transitional metal sulfides in sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Anatase TiO 2 nanopores are successfully prepared through alternating voltage induced electrochemical synthesis (AVIES) approach at room temperature. When utilizing TiO 2 nanoporous materials as an anode for Na-ion battery, it delivers a reversible charge-discharge capacity of around 180 mA h g −1 at 0.2 C (67 mA g −1 ) after 200 cycles. Meanwhile, it also shows a good cycling performance and a high rate capability due to unique nanoporous structures, which promote electrolyte wetting and facilitate diffusion of Na + . Additionally, cyclic voltammetry demonstrate that the sodium-ion storage of as-prepared TiO 2 is a cooperative control behavior of diffusion and capacitance, but mainly controlled by capacitive behavior, which further facilitates a rapid (de-)intercalation of Na + . [ABSTRACT FROM AUTHOR]

Three-dimensional copper oxide structures composed of single crystal nanosheets have been successfully prepared by a green electrochemical alternating voltage approach. This special structure of copper oxide grown along the [0 1 0] direction can be effective to accommodate the volume expansion during charge–discharge cycles. The obtained product as anode materials in lithium-ion batteries displays outstanding electrochemical performances with a high reversible capacity of 635.2 mA h g −1 after 50 cycles at 100 mA g −1 close to the theoretical capacity of copper oxide (674 mA h g −1 ). [ABSTRACT FROM AUTHOR]

A green and one-step method of electrochemical alternating voltage has been utilized to form NiO quantum dots/graphene flakes (NiO-dots/Gh) for supercapacitor applications. NiO quantum dots (∼3 nm) are uniformly deposited on few-layer graphene surfaces by oxygen functional groups on graphene surface that is naturally utilized to bridge NiO and graphene through Ni–O–C bands, which exhibits outstanding specific capacitance 1181.1 F g −1 at a current density of 2.1 A g −1 and rate behavior 66.2% at 42 A g −1 as NiO dots can be fleetly wired up to current collector through the underlying graphene two-dimensional layers. The NiO-dots/Gh composite is further undertaken in asymmetric supercapacitors with high energy density (27.3 Wh kg −1 at 1562.6 W kg −1 ). [ABSTRACT FROM AUTHOR]

[Display omitted] • Strong binding energy of sulfonated CDs toward Zn2+ could manipulate the Zn nucleation process. • Electrostatic repulsion between SO 4 2− and negative charge of CDs could mitigate formation of by-products. • Interfacial hydrogen bonds between CDs and water could restrain the water-induced side reaction. • Robust Zn-electrolyte interface with an ultra-durable lifespan of 4000 h at 1 mA cm−2 was successfully achieved. Water-induced side reactions and the growth of zinc dendrites are generally considered as the key problems hindering the development of zinc batteries. Herein, robust electrode/electrolyte interface is successfully constructed via introducing carbon dots (CDs) additive into hybrid electrolyte to enhance the stability of Zn anode. The CDs with -SO 3 − groups deliver strong binding energy toward Zn, which can reduce the nucleation barrier, thus favoring the homogeneous Zn deposition, as successfully evidenced by theoretical DFT calculation and intuitive in-situ optical microscope observation. Meanwhile, the zincophilic CDs can be preferentially adsorbed on the surface of Zn electrode, further diminishing water-induced adverse reaction by virtue of the electrostatic repulsion between SO 4 2− and negative charge of CDs. Accordingly, benefiting from the synergetic effect, the hybrid electrolyte with CDs endows Zn||Zn symmetric cell a prolonged lifespan over 4000 h with steady voltage fluctuation at 1 mA cm−2. [ABSTRACT FROM AUTHOR]

Carbon materials have been widely applied in the energy storage devices, however, the preparation of suitable carbon materials for sodium-ion batteries (SIBs) is still a challenge. In this paper, N-doped porous carbon material (NDPCs) with rose-like structure has been successfully prapared through pyrolysis of the as-prepared polyimides in-situ. The NDPCs shows rose-like structure derived from 2D nanosheets, an expanded interlayer distance of 0.387 nm, a high specific surface area of 215.7 m 2 g −1 and the electrochemical performances for Na-ion batteries are systematically investigated. A high reversible specific capacity of 240 mAh g −1 at a current density of 100 mA g −1 is attained and a specific capacity of 224 mAh g −1 is remained even after 100 cycles. Remarkably, even at a high current density of 3.2 A g −1 , the reversible specific capacity of 104 mAh g −1 can be observed. This excellent performance of NDPCs electrode may be ascribed to its superior structure, since the micropore/mesopore might efficiently shorten the diffusion distance of Na-ion and the enlarged interlayer spacing of 0.38 nm is significant for Na-ion insertion/extraction. Significantly, the approach to prepare carbon materials from PI may be generalized to other polymers. [ABSTRACT FROM AUTHOR]

Cube-shaped porous carbon (CPC) was obtained from the carbonization of MOF-5 (Zn 4 O(OOCC 6 H 4 COO) 3 ) crystals and shows abundant micro/mesopores, high mechanical strength, largest surface area (2316 m 2 g −1 , BET method) and good electrical conductivity (a high weight ratio 98.17/1.83 of C/O). When utilized as anode material for sodium-ion batteries, the CPC presents a high overall sodium storage capacity ∼240 mAh g −1 at a current density of 100 mA g −1 after 100 cycles, and maintains a high specific capacity of 100 mAh g −1 after 5000 cycles at a current density of 3200 mA g −1 . For the advantages of this unique carbon framework structure, the CPC might be a promising anode material for the application of SIBs. [ABSTRACT FROM AUTHOR]

Mesoporous NiCo 2 O 4 hollow submicrospheres have been prepared through a facile and scalable soft template method utilizing a reflux route. The as-obtained mesoporous NiCo 2 O 4 hollow submicrosphere electrode exhibits high specific capacitance of 987 F g −1 at 1 A g −1 , superior capacity retention rate of 79.4 and 62.8% at 20 and 50 A g −1 , and remarkable cycling stability with almost no capacity loss at 5 A g −1 over 5000 cycles. The superior electrochemical performances can be attributed to the unique mesoporous hollow structure with a large specific surface area (189.7 m 2 g −1 ) and superior pore-size distribution (3–5 nm). To further demonstrate its practical application, an asymmetric supercapacitor based on the mesoporous NiCo 2 O 4 hollow submicrospheres as the positive electrode and activated carbon as the negative electrode is fabricated, which manifests high energy density of 27.2 Wh kg −1 at the power density of 102 W kg −1 or high power density of 8.16 kW kg −1 at the energy density of 10.9 Wh kg −1 and exceptional long-term cycling stability with 108.1% of the initial capacity retention at 3 A g −1 over 10000 cycles. These impressive results render this NiCo 2 O 4 hollow submicrospheres promising as one of the most attractive candidates for supercapacitors in practical applications. [ABSTRACT FROM AUTHOR]

Cathodic corrosion, a green electrochemical method, has been employed to obtain Sb nanomaterials utilized as anode material for lithium-ion batteries and sodium-ion batteries. Interestingly, two different corrosion mechanisms are found, coming from the impact of electrolyte, resulting in the formation of hexagonal and amorphous Sb in aqueous and organic solution, respectively. With the help of water-soluble carboxymethyl cellulose binder and the electrolyte additive fluoroethylene carbonate, both hexagonal and amorphous Sb electrodes exhibit good cycling stability when utilized as anode materials for lithium-ion batteries and sodium-ion batteries. Additionally, both the hexagonal and amorphous Sb electrodes show very good rate capability in lithium-ion batteries. Even at high current density (2000 mA g −1 ), the hexagonal and amorphous Sb give reversible capacities of 422 and 379 mA h g −1 , respectively. Surprisingly, when used as anode materials for sodium-ion batteries, the hexagonal Sb electrode exhibits a good rate performance of 632, 625, 569, 515 and 426 mA h g −1 at a current density of 100, 200, 500, 1000, and 2000 mA g −1 , respectively. However, limited rate performance is observed from the amorphous Sb electrode in case of sodium-ion battery due to the large impedance. [ABSTRACT FROM AUTHOR]

3D network-like mesoporous NiCo 2 O 4 nanostructures have been successfully fabricated through a solvothermal route coupled with a post annealing treatment. Benefiting from its advantages of the unique 3D network-like structures with large specific surface area (170.6 m 2 g −1 ), abundant mesoporosity (5–10 nm) and high electronic conductivity, the as-obtained NiCo 2 O 4 manifests high specific capacitance of 931 F g −1 at 3 A g −1 , remarkable capacity retention rate of 85.2 and 72.5% at 20 and 50 A g −1 compared with 2 A g −1 and superior cycling stability of 125.2% of initial capacity retention over 1000 cycles at 3 A g −1 . The excellent electrochemical performances coupled with its facile and cost-effective way will render the 3D network-like mesoporous NiCo 2 O 4 nanostructures as attractive electrode materials for promising application in supercapacitors. [ABSTRACT FROM AUTHOR]

Ion migration is the most fundamental process in the field of energy storage and conversion. During the charge-discharge cycle, the (de)intercalation of guest ions in solid host particles as electrode materials change the distribution of element, phase and stress in the particle and give rise to crushing and degradation, which will influence the electrochemical behavior of the particles. New methods are constantly being proposed to probe the electrochemical reactions on individual particle for understanding the mechanism of the process. In this short review, we highlight some pioneer works from two different perspectives, namely direct electrochemical detection methods, such as nano-impact method, nanoprobe detection and flowing particle analysis, and indirect optical analysis methods utilizing X-ray imaging, infrared near-field nanoscopy, Raman microscopy and surface plasmon resonance microscopy. [ABSTRACT FROM AUTHOR]