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Aqueous zinc‐ion batteries (ZIBs) are promising candidates for grid‐energy storage due to their safety and cost‐effectiveness. However, the detrimental hydrogen evolution reaction (HER) and dendrite growth on Zn‐metal anodes severely limit their applications. Herein, trace hydrophobic hyamine (HQA, 0.78 mmol L−1) is introduced as an electrolyte additive to improve the electrochemical performance of the Zn anode. Experiments and theoretical calculations revealed that cationic HQA can preferentially adsorb onto the anode surface to inhibit the HER and promote the uniform distribution of Zn ions by forming a water‐lean electric double layer (EDL). Moreover, the oriented adsorption of HQA induced exposure of the Zn (002) plane and prevented dendrite growth. Therefore, the symmetric cells using the HQA‐containing electrolyte exhibited stable cycle performance for more than 1600 h. Even at a high‐density current of 5 mA cm−2, it has a high cumulative capacity of 3250 mAh cm−2. It exhibited an excellent deep‐discharge performance (80%) with a stable cycle for 175 h. The Zn||NH4V4O10 full cell exhibited a high specific capacity and cycle stability at 4.0 A g−1 due to the excellent reversibility of Zn anode. These results provide a new and low‐cost approach for electrolyte design and EDL optimization of high‐performance zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

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]

The difficulty in matching cathode and anode kinetics due to slow ion transport in anodes constrains the development of lithium‐ion capacitors. Heterogeneous structures with built‐in electric field can promote lithium‐ion migration and improve the anode reaction kinetics. However, the valence evolution of metal elements in heterostructures during charging/discharging processes is often overlooked. Inspired by theoretical calculations, transition metal selenides heterostructures (FeSe2/CoSe2) with low migration energy barriers (Eb = 0.35 eV) are successfully engineered and fabricated. As expected, the designed heterostructure material exhibits outstanding rate performance (512 mAh g−1 at 30 A g−1) and ultra‐high pseudocapacitance contribution (98.02% at 1.0 mV s−1), exceeding the state‐of‐the‐art values for anodes. Impressively, synchrotron X‐ray absorption spectroscopy (SXAS) and ex situ XPS find that the valence states of the Fe and Co elements in the heterogeneous structure gradually increase as charging and discharging proceeds, inducing a continuous climb in reversible specific capacity, while further reducing the migration energy barrier in the heterogeneous structure (Eb = 0.20 eV). This work reveals that the valence states of iron and cobalt elements increase as charging and discharging proceeds, providing theoretical guidance for improving the anode kinetics and revealing the capacity rise mechanism of other transition metal compounds. [ABSTRACT FROM AUTHOR]

Aqueous zinc anode has been re‐evaluated due to the superiority in tackling safety and cost concerns. However, the limited lifespan originating from Zn dendritic and side reactions largely hamper commercial development. Currently, the coating prepared by simple slurry mixing is leaky and ineffectively isolate sulfate and water. Herein, inspired by the DFT calculations and the easy hydrolysis characteristic of MIL‐125 (Ti), an in‐situ grown high‐dense TiO2‐x solid electrolyte interphase (HDSEI) with rich oxygen vacancies is successfully constructed in an aqueous electrolyte, in which the oxygen vacancies not only strengthen the hydrogen binding force thereby inhibiting the hydrogen precipitation by‐reaction, but also reduce the migration energy barrier of zinc ions and enhance the mechanical properties. Profiting from the HDSEI, symmetric Zn cells survive up to remarkable 4200 h at 1 mA cm−2, nearly 42‐times than that of bare Zn anodes. In situ optical microscopy clearly reveals that the in situ grown HDSEI homogenizes the zinc deposition process, while bare zinc without HDSEI shows significant dendrites, confirming the protective nature of HDSEI. Furthermore, full Zn ion capacitors can deliver excellent electrochemical performance, providing a feasible in situ approach to construct HDSEI to implement dendrite‐free metal anodes. [ABSTRACT FROM AUTHOR]

Aqueous Zn‐ion energy‐storage deviceswith metal Zn as anodes, including batteries and capacitors (ZIBs and ZICs), is largely hindered by dendritic growth and low coulombic efficiency since the side reactions between Zn anodes and electrolyte, originating fromthat targeted and efficient isolation of H2O and SO42− is extremely challenging. Herein, inspired by density functional theory (DFT) that the 2D angstrom level metal‐organic framework(2D‐MOF) is highly selective for the passage of ions, simultaneously excluding the SO42− and H2O but allowing Zn2+ selective conduction. Moreover, 2D‐MOF exhibits better mechanical strength compared with 3D‐MOF, which is more conducive to inhibit dendrite growth. Impressively, benefiting from the 2D‐MOFlayer, symmetric Zn cells survived up to 2000 h at 4 mA cm−2,near 20‐times that of bare Zn anodes. Coupling it with cathode for ZICs and ZIBs, excellent electrochemical performances are presented. Importantly, symmetric Na cells with 2D‐MOF as ionic sieve membrane also deliver small polarization and outstanding performance, indicating that this study provides an efficient strategy to develop long‐life metal anode. [ABSTRACT FROM AUTHOR]

Bi-doped carbon dots (Bi-CDs) with rich polar groups and good compatibility were employed as co-deposition electrolyte additives to homogenize Li+ flux for dendrite-free Li deposition. High coulombic efficiency (99.0%) and long-term stability (800 h) with reduced overpotential (∼15 mV) were achieved after introducing Bi-CDs in conventional electrolyte for high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (PIBs) have appealed increasing attention due to the inexpensive K‐element resources and satisfactory electrochemical properties. Presently, there are still challenges for developing desirable anode materials. Two‐dimensional metal sulfides exhibit high specific capacity as host for PIBs, yet the dissolution and agglomeration of unstable reaction intermediate KxSy (K2S, K2S5) inescapability induces large loss of active ingredients and poor reactions reversibility, leading to inferior lifespan. Herein, polar polysulfide VS4 is introduced into SnS nanosheets with constructing layered VS4/SnS heterostructure anchored in graphene scaffold (VS4/SnS@C). In this framework, VS4 with unsaturated bridging (S2)2– can act as the anchoring sites to stabilize intermediates KxSy with efficient entrapment effects. Moreover, the heterostructure can maintain layered SnS and regulate the distribution of KxSy with high conversion reversibility. The reaction reversibility and intermediate absorptivity are enhanced, as confirmed by in situ X‐ray diffraction analysis and theoretical calculations. Consequently, the VS4/SnS@C electrode exhibits ultra‐long lifespans, which achieves a capacity of 168.4 mAh g–1 at 1 A g–1 after 6000 cycles. This strategy of heterostructure design facilitates the understanding of K‐storage mechanisms and significantly enhances the reaction reversibility, providing a thought to address the challenges in metal sulfide anodes toward the development of high‐performance PIBs. [ABSTRACT FROM AUTHOR]

Konjac glucomannan (KGM) featuring abundant oxygen functional groups has been elaborately designed to enhance Zn reversibility. Importantly, –OH and C＝O groups as active sites could redistribute the Zn2+ concentration field and modulate the plating/stripping rate, further enabling uniform Zn deposition without dendrite growth. The Zn@KGM anode enables an advanced Zn-ion supercapacitor to deliver an impressive rate performance and cycling stability (up to 5000 cycles accompanied by a coulombic efficiency of 99.8%). [ABSTRACT FROM AUTHOR]

Fabrication of Bi/C composites is a common approach to alleviate the severe volume expansion of Bi alloy‐based anodes with a high theoretical capacity of 3800 mAh cm−3 for lithium ion batteries (LIBs). However, the complicated and tedious synthetic routes restrict its large‐scale preparation and practical applications. Herein, a spongiform porous Bi/C composite (marked as Bi@PC) through the carbothermal reduction (CTR) method is constructed. Bi nanodots are in situ confined in a porous carbon substrate activated by the gases produced from the decomposition of the sodium phytate precursor, indicating the feasibility and simplicity of this route. In charge/discharge processes, Bi nanodots embedded in carbon matrix are effective enough to accommodate the strain change and shorten the migration distance. In addition, the porous carbon forms an efficient conductive network for electron shutting. When utilized for lithium storage, a superb capacity of 520 mAh g−1 at 0.2 A g−1 after 100 cycles and a satisfying long cyclic stability of 380 mAh g−1 at 0.5 A g−1 after 500 cycles are achieved. The excellent Li‐storage performance and this handy preparation method jointly make this Bi/C composite a potential anode for LIBs, and could inspire the preparation of other alloy‐type anodes. [ABSTRACT FROM AUTHOR]

High‐efficiency energy storage technologies and devices have gained numerous attention because of their ever‐increasing requirement. Sodium‐ion capacitors (SICs), as a burgeoning electrochemical energy storage device, combine virtues of rechargeable batteries and electrochemical double layer supercapacitors, delivering both high energy–power density and long cycling life. In the past decades, great efforts have been made to find suitable anode material to conquer the kinetic imbalance between the battery‐type anode with sluggish bulk redox reaction and the capacitor‐type cathode with fast ion absorption/desorption process. By exploring high‐rate performance anode materials, the great reaction kinetic gap between cathodes and anodes can be narrowed down, which directly affects the energy–power densities of SICs. In this article, an overview of advanced battery‐type anode materials is offered for high‐performance SICs with an emphasis on anode structural design and improved energy–power density, including carbonaceous materials, metallic compounds, MXene, organic polymers, and so on. Furthermore, the implementation of presodiation for the sake of optimizing the SICs is also illustrated. Finally, the challenges faced and the perspectives for future developing trends of SICs are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Designing potential anodes for sodium‐ion battery with both remarkable durability and high‐rate capability has captured enormous attention so far. The engineering of size and morphology is deemed as an effective manner to boost the electrochemical properties. Owing to the anisotropic self‐assembly of iron selenide, rod‐like FeSe2 coates with nitrogen‐doped carbon is prepared through the thermal reaction of Prussian blue with selenium. Notably, the cyano groups are effectively transformed into N‐doped carbon with FeNC bonds, which uniformly coats FeSe2, prompting Na+ transportations. Interestingly, the particle size is tailored by heating rates, along with increased carbon content, leading to broadened energy levels for redox reaction. Bestowed by these advantages, the FeSe2/N‐C as Na‐storage anode delivers impressive electrochemical properties. Even at a rather high rate of 10.0 A g−1, a considerable capacity of 308 mAh g−1 is yielded over 10 000 loops. Supported by the detailed analysis of kinetic features, reduced size of particles could bring about the enhanced contributions of pseudocapacitive and quickening rate of ions transferring. The phase evolutions are further investigated by in situ EIS and ex‐situ technologies. The work is expected to provide a new strategy to prepare metal‐selenide with controllable size and induce the faster kinetic of high‐rate materials. [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]

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]

S odium t itanate (Na 2 Ti 6 O 13 ) cuboid is successfully prepared and employed for anode electrode materials in sodium-ion batteries (SIBs). Their sodium storage properties are presented by undertaking polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC) as different binders. At a current density of 0.1 C, the sodium titanate cuboid with CMC and PVDF exhibits discharge capacity of 269.5 mAh g −1 and 251.0 mAh g −1 , respectively. At the 200th charge/discharge cycle, the reserved discharge capacity for Sodium titanate cuboid electrode with CMC binder is 173.6 mAh g −1 , amounting to a capacity retention of 94.4%, much higher than that employing PVDF as binder (the discharge capacity of 69.3 mAh g −1 and the capacity retention of 54.1%). The rate capability test and the Coulombic efficiency data also manifest that the Sodium titanate cuboid utilizing CMC as binder is superior to the ones with PVDF. These enhanced electrochemical performance mainly derive from the strong cohesive strength of CMC binder and the swellability of PVDF binder, verifying the importance of a binder to the optimization of sodium storage behavior. [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]

Correction for 'Highly stable zinc metal anode enabled by oxygen functional groups for advanced Zn-ion supercapacitors' by Kangyu Zou et al., Chem. Commun., 2021, 57, 528–531, DOI: 10.1039/D0CC07526D. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (PIBs) are currently drawing increased attention as a promising alternative to lithium‐ion batteries (LIBs) owing to the abundant resource and low cost of potassium. However, due to the large ionic radius size of K+, electrode material that can stably maintain K+ insertion/deintercalation is still extremely inadequate, especially for anode material with a satisfactory reversible capacity. As an attempt, nitrogen/carbon dual‐doped hierarchical NiS2 is introduced as the electrode material in PIBs for the first time. Considering that the introduction of the carbon layer effectively alleviates the volume expansion of the material itself, further improves the electronic conductivity, and finally accelerates the charge transfer of K+, not surprisingly, NiS2 decorated with the bifunctional carbon (NiS2@C@C) material electrode shows excellent potassium storage performances. When utilized as a PIB anode, it delivers a high reversible capacity of 302.7 mAh g−1 at 50 mA g−1 after 100 cycles. The first coulombic efficiency is 78.6% and rate performance is 151.2 mAh g−1 at 1.6 A g−1 of the NiS2@C@C, which are also notable. Given such remarkable electrochemical properties, this work is expected to provide more possibilities for the reasonable design of advanced electrode materials for metal sulfide potassium ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Zinc ion batteries (ZIBs) suffer from severe corrosion effects and dendrite growth on the unstable anode/electrolyte interface (AEI) during the plating/stripping process. Therefore, it is of great significance to build a stable AEI enabling a long lifetime for ZIBs. Herein, trace tea polyphenols (TP) were introduced firstly as additive of zinc acetate electrolyte to protect zinc anode from corrosion invasion and boost uniform zinc deposition, thus achieving reversible dendrite-free zinc anode. In situ synchrotron radiation X-ray imaging was conducted to illustrate the positive role of TP molecules in the uniform plating process of zinc. The stable AEI induced by the specific adsorption of TP molecules reduced hydrogen and oxygen evolution side reactions and increased the coulombic efficiency. The TP additive with an ultralow dosage of 0.028 g L−1 delivered favorable cycling stability of 720 h at 0.5 mA cm−2 and 0.5 mAh cm−2. The Zn-Na 3 V 2 (PO 4) 3 full cell assembled with the hybrid Zn(Ac) 2 -TP electrolyte contributed an energy density of 130 mAh g−1 at the current density of 0.2C and enhanced cycling stability of 78% retention after 300 cycles. These results will provide new insights into additive engineering for aqueous electrolytes and the fundamental understanding of AEI phenomena for high performance ZIBs. [ABSTRACT FROM AUTHOR]

The electrochemical performance of the cathode material is influenced by its structure, including morphology, pore size, specific surface area, layer spacing, impurity content, and species. Each of these factors plays a distinct role in the energy storage process of the electrode. The purpose of this review is not only to provide the relationship between the structure and mechanism of cathode materials, but also to provide directional guidance for optimizing electrochemical performance of the materials. [Display omitted] • Critically reviewing the applications of various cathode materials in MIHCs (Li, Na, K and Zn). • Discussing the relationship between material structure and energy storage mechanism. • Summarizing the methods of optimizing electrochemical properties of cathode materials. Metal ion hybrid capacitors (MIHCs) consist of both capacitance-type electrodes and battery-type electrodes, thereby combining the advantages of metal ion batteries and supercapacitors. Nevertheless, the disparity between the specific capacity and rate performance of the cathode and anode materials suggests that the current performance of MIHCs does not meet practical requirements. The performance of MIHCs is affected by the type, composition, and morphology of the cathode material, affirming their essential role as critical components. Therefore, there is a need to concentrate on and discuss the electrochemical properties of electrode materials, as well as strategies aimed at enhancing their electrochemical performance. This article introduces the composition, types, and energy storage mechanisms of MIHCs. Subsequently, a review is conducted on the cathode materials used in lithium, sodium, potassium, and zinc ion capacitors, with emphasis on their physical and chemical properties and the resulting electrochemical performance. Moreover, a comprehensive investigation is conducted to explore effective strategies for enhancing the electrochemical properties of materials, incorporating a substantial number of theoretical calculations and experimental results. Finally, this review provides valuable suggestions for the development and large-scale production of cathode electrode materials for MIHCs (Li+, Na+, K+, and Zn2+), addressing current issues and proposing potential research directions. [ABSTRACT FROM AUTHOR]

Titanium dioxide, promising anode materials for sodium ion batteries, nonetheless, suffers from its inferior charge transfer kinetics owing to low diffusion coefficient and poor electronic conductivity, which results in its unsatisfactory high-rate capability. Here, an oxygen vacancy (OV) engineering assisted in high-content anion (S/Se/P) doping strategy to enhance its charge transfer kinetics for ultrafast sodium-storage performance is proposed to address these issues and expectative results have been obtained. [Display omitted] The rate-determining process for sodium storage in TiO 2 is greatly depending on charge transfer happening in the electrode materials owing to its inferior diffusion coefficient and electronic conductivity. Apart from reducing the diffusion distance of ion/electron, the increasement of ionic/electronic mobility in the crystal lattice is also very important for charge transport. Here, an oxygen vacancy (OV) engineering assisted in high-content anion (S/Se/P) doping strategy to enhance charge transfer kinetics for ultrafast sodium-storage performance is proposed. Theoretical calculations indicate that OV-engineering evokes spontaneous S doping into the TiO 2 phase and achieves high dopant concentration to bring about impurity state electron donor and electronic delocalization over S occupied sites, which can largely reduce the migration barrier of Na+. To realize the speculation, high-content anion doped anatase TiO 2 /C composites (9.82 at% for S in A-TiO 2– x -S/C) are elaborately designed. The optimized A-TiO 2– x -S/C anode exhibits extraordinarily high-rate capability with 209.6 mAh g−1 at 5000 mA g−1. The assembled sodium ion capacitors deliver an ultrahigh energy density of 150.1 Wh kg−1 at a power density of 150 W kg−1 when applied as anode materials. This work provides a new strategy to realize high content anion doping concentration, and enhances the charge transfer kinetics for TiO 2 , which delivers an efficient approach for the design of electrode materials with fast kinetic. [ABSTRACT FROM AUTHOR]

The Sb@CN nanofibers are efficiently fabricated and present excellent potassium storage performance, especially the long cycle stability with a reversible capacity of of 360.2 mAh g−1 at 50 mA g−1 after 200 cycles and 212.7 mAh g−1 after 1000 cycles even at 5000 mA g−1, which is one of the most outstanding potassium storage performances of Sb anode up to now. Antimony-based materials with high theoretical capacity are known as promising anodes for potassium-ion batteries (PIBs). However, they still face challenges from the large ionic radius of the K ion, which has sluggish kinetics. Much effort is needed to exploit high-performance electrode materials to satisfy the reversible capacity of PIBs. In this paper, nano Sb confined in N-doped carbon fibers (Sb@CN nanofibers) were successfully prepared through an electrospinning method, which was designed to improve potassium storage performances. Sb@CN nanofibers benefit from the fact that the synergy between the porous nanofiber frame structure and the uniformly distributed Sb nano-components in the carbon matrix can effectively accelerate the ion migration rate and reduce the mechanical stress caused by K+ insertion/extraction, Sb@CN nanofiber electrodes thus exhibited excellent potassium storage performance, especially long cycle stability, as expected. When utilized as a PIB anode, they delivered high reversible capacity of 360.2 mAh g−1 after 200 cycles at 50 mA g−1, and a particularly stable capacity of 212.7 mAh g−1 was also obtained after 1000 cycles even at 5000 mA g−1. Given such outstanding electrochemical performances, this work is expected to provide insight into the development and exploration of advanced alloy-type electrodes for PIBs. [ABSTRACT FROM AUTHOR]

Aiming at the problems of poor cycle stability of carbon-based materials in potassium ion batteries, functionalized nitrogen and sulfur co-doped carbon dots (CDs) are applied to improve the potassium storage performance of electrode materials. In this work, the functionalized CDs are used to regulate the structure and morphology of the polypyrrole in-situ during the polymerization process of pyrrole monomer. Concretely, the original strip-like fibrous polypyrrole can be induced to become bead-like particle with the disappearance of fiber shape, and with the increase of the amount of carbon dots, the active particles increased. Compared with pure polypyrrole derived carbon, the carbon-dot-regulated polypyrrole derived carbon exhibits more excellent cycling performances with a shorter ion transmission and transfer path, more active sites, increased contact area with the electrolyte and improved structural stability. The specific capacity of the carbon anode carbonized from polypyrrole (C-ppy-NSCDs-100) regulated by 100 mg of carbon dots could reach 360.2 mAh g−1 at 0.1 A g−1, showing the application potential of carbon dots in improving electrochemical potassium storage by regulating the morphology of carbon-based materials. Predictably, these unparalleled features of CDs can be expected to inspire more exciting results in potassium-ion energy storage systems. • A series of polypyrrole carbon-based materials were obtained with the inducers of carbon dots. • The C-ppy-NSCDs-100 anode exhibited a specific capacity of 155.4 mAh g−1 at 1.0 A g−1 after 495 cycles. • The introduction of carbon quantum is an effective way to improve electrochemical potassium storage. [ABSTRACT FROM AUTHOR]

Potassium-ion battery (PIB) is a promising candidate in grid energy storage field because of the abundant potassium resource and its low cost. More efforts should be made to research anode material with long cycling performance due to the fading potassium capacity of graphite. Honeycomb hard carbon (HHC) with uniform pore structure and weakly ordered turbostratic domains was successfully prepared from carbon quantum dots (CQDs) through the calcination with the assistance of SiO 2 nanospheres. As anode material for PIBs, HHC delivered a high specific capacity of 195.3 mA h g−1 and 67.43% capacity retention after 150 cycles at a current density of 0.1 A g−1. The electrochemical behaviors of HHC electrode were investigated in detail by electrochemical impedance spectroscopy (EIS) at various voltages and calculation of capacitive contribution, exhibiting favorable potassium storage property. Image 1 • Honeycomb hard carbon is prepared from carbon quantum dots. • Honeycomb hard carbon exhibits great potassium storage performances. • Honeycomb hard carbon/K electrode exhibits favorable kinetic behaviors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The functional C 60 layer synergistically inhibit Zn dendrites and side reactions. • C 60 with good electron affinity benefits the ohmic contact at interface. • The C 60 coating induces Zn2+ ions to orient along the Zn(0 0 2) plane. • Symmetric cells deliver low voltage hysteresis and prolonged lifespan of 3800 h. Although the aqueous zinc batteries are deemed as the most competitive alternatives in the next-generation batteries, there are still annoying issues, including obdurate dendrites formation and side reactions, limiting practical applications. Hence, a uniform artificial C 60 layer via an ex-situ approach is successfully assembled to construct robust Zn anode (denoted as Zn@C 60). The functional C 60 layer allows the formation of the ohmic contact interface between the C 60 layer and Zn anode, inducing a low nucleation barrier and restraining 2D diffusion of Zn ions. More importantly, density functional theory calculations and simulation of the electric field contribution demonstrate that the C 60 layer can facilitate the deposition of Zn on the Zn(0 0 2) plane and homogenize the electric field distribution. Consequently, the Zn@C 60 electrode is obtained with a cycling stability over 3800 h at 0.25 mA cm−2 in symmetric cells, excellent coulombic efficiency for 1400 h in half cells, and together with better cycling stability and enhanced rate performance in full cells. Significantly, the C 60 layer protection strategy provides a new view for an excellent dendrite-free Zn metal anode. [ABSTRACT FROM AUTHOR]

Hard Carbons (HCs) are widely investigated as anode materials for Sodium-ion batteries (SIBs), for the abundance of the precursors and their easy synthesis. However, the intercalation of Na+ in the HCs is a big challenge for the design of high-performance SIBs. Heteroatom-doping can effectively facilitate the intercalation of Na+ in the anode material. Herein, a series of double and triple-atom phosphorus-nitrogen, phosphorus-sulfur, nitrogen-sulfur and phosphorus-nitrogen-sulfur in the camphor wood (Cmph) derived-HCs are fabricated, and their electrochemical performances as anodes for SIBs are investigated. The P–N–S-Cmph delivers high initial coulombic efficiency (ICE) of 70.74%%, an outstanding rate performance and good cycling stability, maintaining a specific capacity of 280 mAh g−1 at 2000 mA g−1 after 500 cycles. The excellent performances of the anode materials are assigned to the synergetic effect of the heteroatom-doping of S, N and P enlarging the interlayer spacing of the doped-Cmph-HCs, increasing the intercalation/deintercalation rate of Na+ in the HCs; disposing more active sites for the Na+ storage. In addition, sulfur can reversibly react with Na+, reducing the irreversible consumption of Na+ by the surface functional groups. This work presents a simple and effective method of designing high performance anode materials for SIBs. • P, N and S co-doping in the biomass hard carbon anodes are developed. • P, N and S-doping increased the Na+ intercalation rate in the anode materials. • S-doping provided more active sites for Na+ storage in the hard carbon anodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The DTBC-Zn anode was designed via an interfacial dissolution-coordination strategy. • The DTBC network improves the thermos-kinetics properties of Zn anode. • Zn2+ migrate along the coordination skeletons to achieve (0 0 2) plane deposition. • The DTBC-Zn anode enabled dendrite-free and by-product-free Zn deposition. Severe side reactions and dendrite growth are widespread in zinc anodes due to the aqueous electrolyte and the inhomogeneity of the Zn surface. Constructing an artificial interfacial layer on the zinc anode is a direct and effective strategy to solve these problems. Herein, a dithio-bridged chelate (DTBC) network consisting of zinc dimethyldithiocarbamate molecules was in situ constructed on the zinc surface via a facile interfacial dissolution-coordination strategy. The experiment and theoretical calculation revealed that the DTBC network simultaneously improves the thermos-kinetics properties of zinc anode. Moreover, the dithio groups in the DTBC network can induce the preferred plating of Zn along the (0 0 2) crystal plane and suppress dendrite growth. The DTBC-Zn electrode delivered an extended lifetime of over 1200 h with an ultralow polarization of ∼27.3 mV at 0.5 mA cm−2. The capacity retention rate of DTBC-Zn|MnO 2 full cell was as high as 97.98 % after 1600 cycles, further confirming the feasibility of the robust dithio-bridged chelate network for stabilizing thermo-kinetics of zinc anode. This work contributes a simple and effective way to construct high-performance zinc anodes for aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]

• The S-doped hard carbon delivered an enhanced ICE of 66.61% as well as excellent rate performance. • The as-acquired anode material exhibited good cycling performance with a reversible capacity of 145.6 mAh/g over 500 cycles at 2000 mA g−1. • The S-doping can expand the interlayer spacing of the hard carbon and provide more active sites for the Na+ storage. The intercalation/deintercalation of Na+ in the hard carbon (HC) has been widely investigated for the construction of high performances sodium-ion batteries (SIBs). In this work, a variety of sulfur-doped HCs were obtained by simple pyrolysis of the sublimated sulfur and the camphor tree (S-Cmph) derived material. When used as anode for SIBs, the S-Cmph-700 (pyrolyzed at 700℃) delivered a capacity of 616.7 mAh/g with an ICE of 66.61 %, high than that of the untreated material pyrolyzed at 1500℃ (50.11 %) (Cmph-1500). Furthermore, excellent rate performance with specific capacities of 372.3, 323, 282.6, 252.6, 221, 181.2 mAh/g at 40, 80, 200, 400, 800 and 2000 mA g−1 can be achieved, respectively. When the current density returned at 40 mA g−1, the anode recovered a specific capacity of 356.8 mAh/g. In addition, the as-acquired anode material exhibited good cycling performance with a reversible capacity of 145.6 mAh/g over 500 cycles at 2000 mA g−1. The improved electrochemical performances of Cmph-HC anode can be attributed to the benefit of the S-doping, leading to the increase of the interlayer spacing of the anode material, which facilitates the intercalation/deintercalation of Na+ ions in the interlayer spacing of the HC material, and provided more active sites in the Cmph-HC anode for the Na+ ions storage. In addition, sulfur can reversibly react with Na+, limiting the irreversible consumption of Na+ and increase the intercalation rate of Na+ inside the anode material. This work presents a low cost, simple and effective way to synthesize a high performances anode material for the commercialization of SIBs. [ABSTRACT FROM AUTHOR]

A facile route to improve the lithium-storage properties of flake graphite (FG) is proposed through coating pyrolysis carbon from polyvinylidene fluoride (PVDF) assisted by KOH activation. The interplanar distance between the graphene sheets of activated PVDF/FG is enlarged, effectively suppressing the electrode deformation during lithium (de)-intercalation. More edge and porous structures of PVDF/FG arising from KOH activation on graphite flakes contribute to improved electron and ion transport, leading to great improvement in its rate and cycling performances. The initial specific capacity of the activated PVDF/FG is 476.6 mAh g −1 at 50 mA g −1 and when the current increases to 1000 mA g −1 , the value still retains 142.6 mAh g −1 . [ABSTRACT FROM AUTHOR]

• N-rich carbon nanotubes with long aspect ratio are constructed by a simple template method. • The nitrogen content in the carbon nanotubes is up to 15.7%. • Excellent cycle durability and rate capability are obtained in sodium/lithium ion batteries. • Quantitative kinetic analysis reveals the dominated capacitive contribution. An effective design of carbon materials with appropriate nanoarchitecture and optimized physicochemical property is critically demanded for superb lithium/sodium storage capacities. N-rich (up to 15.7%) hollow carbon nanotubes (NCNT) with long aspect ratio are well developed via a template method by exploring polypyrrole as the high nitrogen-containing carbon precursor. Owing to the hollow structure with large cavity and long aspect ratio, the NCNT exhibits Li+/Na+ storage capability with favorable volume buffer and rapid ion and electron transfer at high rate, resulting in long-term cycling and high-rate property. Meanwhile, the high N content creates abundant active sites and extrinsic defects, facilitating the improved specific capacity and rate performance. Impressively, our NCNT-600 electrode displays a favorable reversible capacity of 132 mAh g−1 after 5000 cycles at 4000 mA g−1 for SIBs and 170 mAh g−1 after 2000 cycles at the same current for LIBs. Further quantitative kinetic analysis reveals the dominated capacitive contribution of Li+/Na+ storage in NCNT, which is attributed to the porous hollow nanotubes and N-rich carbon with volume strain mitigation and enhanced electronic/ionic transfer capability. Given the cost-effectiveness and material sustainability, our work will shed light on the further design of other carbon-based materials for advanced energy storage devices. [ABSTRACT FROM AUTHOR]

Nitrogen or phosphorus doping is a commonly used method to ameliorate the electrochemical properties of carbonaceous material. In this study, nitrogen-rich carbon nanosheets are first prepared and then annealed with NaH 2 PO 4 to synthesize phosphorus doping nitrogen-rich carbon nanosheets. Two obtained materials are utilized as anodes of sodium-ion batteries and potassium-ion batteries, revealing that phosphorus doping can improve sodiation capacity (247.9 vs. 175.1 mA h g−1) and lower potassiation capacity (207.2 vs. 242.6 mA h g−1). To explore the inner reason for this phenomenon, Na+ and K+ diffusion coefficients are surveyed through galvanostatic intermittent titration technique, showing that the electrode with large ion diffusion coefficient delivers a large capacity. This work provides some use for reference in introduction of heteroatoms to carbonaceous anode materials of sodium-ion batteries and potassium-ion batteries. Image 1 • Carbon nanosheets with high P and N contents were prepared. • P-doped N-rich carbon nanosheets exhibited higher sodiation capacity. • N-rich carbon nanosheets performed better in K-storage than Na-storage. • The electrode with large ion diffusion coefficient delivers a large capacity. [ABSTRACT FROM AUTHOR]