Hard carbon (HC) is a highly promising negative electrode for sodium-ion batteries (SIBs). To promote their practical application in sodium-ion batteries, just like graphite materials in the negative electrode of lithium batteries, it is essential to develop HC materials with high reversible capacity and high initial Coulombic efficiency (ICE). Herein, we propose a facile NaOH activation process to create abundant closed pores within bamboo-derived hard carbon. The results show that specific structure optimization can significantly enhance the low-voltage plateau capacity of the modified hard carbon negative electrode and simultaneously deliver a high reversible capacity and high initial Coulombic efficiency (ICE). The optimized BHC-1400-0.2 electrode exhibits a reversible discharge capacity of 334.4 mAh g-1, which is largely attributed to the substantial contribution of the low-voltage plateau region, predominantly (73%) from the low-voltage plateau region, and a high ICE of 88.7%. In addition, the anode presents a reversible capacity of 268.9 mAh g-1 after 500 cycles at 300 mA g-1, corresponding to a capacity retention of 93.4%. Therefore, this work provides a viable technical route for manufacturing high-performance, low-cost, hard carbon anodes for SIBs.

Metal-organic framework (MOF)-modified composite electrolytes are often limited by sluggish room-temperature ion transport, unstable electrode/electrolyte interfaces, and an incomplete understanding of synergistic transport behavior. Herein, a tetramethylthiuram disulfide (TMTD)-confined MIL-101(Cr) poly(vinylidene fluoride-co-hexafluoropropylene) (PH)-based gel polymer electrolyte, denoted as PH-MIL101@TMTD, is developed to regulate Li+ transport and interfacial stability simultaneously. Synchrotron-based characterization, solid-state nuclear magnetic resonance spectroscopy, and multiscale simulations reveal two key effects: the undercoordinated metal sites in MIL-101(Cr) immobilize anions, while the TMTD confined within the MOF channels provides lithiophilic coordination environments and interconnected migration pathways. As a result, a transient coordination relay is established, thereby promoting fast and selective Li+ transport. PH-MIL101@TMTD achieves an ionic conductivity of 1.91 × 10−3 S cm−1 and a Li+ transference number of 0.85 at 30 °C. Benefiting from the accelerated ion transport and stabilized interfaces, LFP|PH-MIL101@TMTD|Li cells deliver a capacity retention of 93.56% after 6000 cycles at 10C and retain 76.86% of the initial capacity after 8000 cycles. Under practical conditions, a high-loading LFP cell retains 90.32% capacity after 550 cycles at 1C, while a cell with a 20 μm Li foil maintains 97.94% capacity retention after 285 cycles at 0.5C. This work provides a mechanistically supported strategy for engineering MOF-based gel polymer electrolytes toward durable lithium metal batteries.

Lithium metal batteries (LMBs) have attracted huge attention due to super-high capacity and low reduction potential of lithium anode constructing high-energy/power density. However, the practical application of LMBs is significantly constrained by lithium dendrite growth and high reactivity of lithium anode. Herein, a novel functionalized interlayer that SbF3 is tandem on HKUST-1 skeleton forming favorable Sb-terminated groups structure (HKSF@PE), which were proposed and fabricated to construct highly stable LMBs. Theoretical calculations demonstrate that the Sb-terminated groups structure in this configuration display strong interaction with lithium, which can act as a cation receptor and adsorption sites, thereby promoting lithium-ion desolvation and improving lithium-ion transport kinetics. Meanwhile, in-situ XRD, Raman, and DRT analyses indicate that the HKSF assist the formation of LiF-rich and lithiophilic Li3Sb alloys at SEI/Li interface, regulating lithium deposition morphology and reconstructing a reinforced SEI interlayer. Consequently, Li|HKSF@PE|Li symmetric cell exhibits exceptional stability over 2500 ​h at 2 ​mA ​cm−2 with 1 mAh cm−2, and Li|HKSF@PE|LFP full cell demonstrates a high-capacity retention of 92.0% after 220 cycles even at a high rate of 5C. This work reveals the important role of terminated groups to achieve homogeneous lithium deposition and provide a way to construct stable LMBs.

The active electronic states in 1T-MoS2 are highly desirable for catalyzing polysulfides conversion. However, stable 1T-MoS2 is difficult to produce using common approaches. Herein, V uniformly doped in-plane 1T-2H heterostructured MoS2 nanosheets (V-MoS2) are prepared by a facile hydrothermal method with a polyoxometalate precursor containing periodic Mo and V atomic arrangement. The doping of V induces the phase transition from semiconducting 2H-MoS2 to metallic 1T-MoS2 and stabilizes the resulted 1T phase. Importantly, the incorporation of V not only modifies the surface electronic property of MoS2, enhancing the active site density, but also improves the adsorption of polysulfides and the catalytic efficiency for sulfur redox reactions. With these advantages, the Li-S batteries using V-MoS2 electrocatalyst achieve accelerated reaction kinetics and superior electrochemical performance. When the S loading of the cathode is 5.41 mg cm- 2, a favorable discharge capacity of 4.98 mAh cm- 2 is obtained with satisfying cycle stability. This work provides an efficient atomic engineering approach for the design of high performance electrocatalyst for Li-S batteries.

The development of low-cost and efficient bifunctional catalysts is of great importance for the advancement of high-performance rechargeable zinc-air batteries. In this study, we present a composite material comprising Pt-decorated NiCo2O4 nanowires enriched with abundant oxygen vacancies, designed as an excellent bifunctional electrocatalyst for both the oxygen evolution reaction and the oxygen reduction reaction. The introduction of Pt atoms and oxygen vacancies onto the NiCo2O4 nanowires was achieved with the assistance of plasma treatment. This approach resulted in a catalyst with a greater number of active sites, enhanced surface conductivity and significantly improved electrocatalytic activity compared to the original NiCo2O4 nanowires. Moreover, the zinc-air battery based on this composite catalyst exhibits a narrow charge/discharge voltage gap and superior stability, which is better than batteries employing commercial noble-metal-based catalysts. This work provides a rational strategy for the construction of high-active and cost-effective Pt-based electrocatalysts.

Graphene as conductive additives for enhancing the electrochemical performance of commercial cathode materials (e.g., LiFePO4, LiCoO2, and LiMn2O4) in advanced Li-ion batteries (LIBs) has attracted great attention in recent years. However, the LiFePO4 and LiCoO2 electrodes usually show a poor rate capability when using graphene as the conductive additive, since its planar structure hinders ion transmission. Herein, a variety of reduced graphene oxides (rGO-x) have been successfully prepared using the modified Hummer's method followed by calcination. The results show that due to a large specific area and moderate defect density, rGO-5 can ensure good enough interfacial contact between active material particles and collector, thus maintaining fast electron/ion transportation. It has been found that LiFePO4 and LiCoO2 electrodes exhibit good lithium storage properties of 160.95 and 139.41 mA h g-1 at a rate of 0.1 C when rGO-5 is utilized as a conductivity additive. Meanwhile, combined with the electrochemical impedance and kinetic exploration, it can be seen that the LiFePO4 and LiCoO2 electrodes demonstrate a high Li+ diffusion coefficient (DLi+) of 6.7 x 10-14 cm2 s-1 and 4.3 x 10-13 cm2 s-1, respectively. Therefore, this research sheds new light on the practical utilization of rGO additives in high-performance lithium-ion batteries.

Hard carbon has become one of the most prominent anode materials for sodium ion batteries (SIBs) owing to its cost-effective and high capacity. High-temperature carbonization is the most common method for synthesizing biomass-derived hard carbon, and optimizing the carbonization temperature is considered an effective strategy for improving initial Coulombic efficiency (ICE) and discharge specific capacity. However, it is challenging how to obtain hard carbon materials that simultaneously exhibit high ICE and high specific capacity. In this work, the initial carbonization temperature is slightly higher than the pyrolysis temperature, and then followed by hightemperature carbonization process. This method effectively both reduces the specific surface area and enhances structural order, which is conductive to achieving higher ICE and capacity. As a result, it exhibits a maximum ICE of 92 % and a reversible capacity of 308 mAh g- 1 when current density is 30 mA g- 1. Furthermore, it also presents excellent cycling performance and maintaining 91.5 % of its capacity subsequent to 500 cycles when the current density is 300 mA g- 1. Therefore, this straightforward and cost-effective method provides a meaningful attempt for the synthesis of other biomass-derived hard carbon as anode materials of SIBs.

>Zn metal anodes are usually subject to grave dendrite growth during platting/stripping, which dramatically curtails the lifespan of aqueous Zn-ion batteries and capacitors. To address above problems, in our work, a novel phosphorus-functionalized multichannel carbon interlayer was designed and covered on Zn anodes. The results demonstrated that the multichannel structure combined with the three-dimensional meshy skeleton can provide more sufficient space for Zn deposition, thereby effectively inhibiting the growth of zinc dendrites. Meanwhile, theoretical calculations also confirmed that the P–C and P=O functional groups from phosphorus-functionalized multichannel carbon interlayer have the decisive influence in reducing the zinc nucleation potential and depositing uniformly zinc. Concretely, the symmetrical battery assembled with phosphorus-functionalized multichannel carbon interlayer-covered Zn anodes possessed a long lifetime of 3300 h at2 mA cm -2 with 1 mAh cm -2 . Furthermore, the full cell with activated carbon cathodes exhibited a high specific capacity of 80.5 mAh g -1 and outstanding cycling stability without capacity decay after 15 000 cycles at a high current density of 5 A g -1 . The superior electrochemical performance exceeded that of most reported papers. Consequently, our synthesized zincophilic interlayer with the unique structure has superior prospects for application in stabilizing zinc anodes and prolonging the lifespan of batteries.

Given the increasing attention to the safety issues of lithium-ion batteries (LIBs) and the continuous rise in the price of lithium and its compounds, it is urgent to explore innovative electrochemical energy device alternatives to LIBs. Major efforts have been devoted to developing rechargeable aluminum-ion batteries (AIBs), owing to their low cost and high energy density derived from the 3-electron redox reaction. Moreover, the dendrite-free plating behavior with room-temperature ionic liquid electrolytes endows AIBs with great safety expectations. A marked hurdle persists in the quest for appropriate cathode materials that can effectively accommodate aluminum ion species in AIBs. This review aims to deliver an integrated overview of the state-of-the-art cathode materials for nonaqueous and aqueous AIBs, with a special emphasis on their underlying electrochemical interaction with electrolytes. The strategies adopted to improve the specific capacity and cyclic performances of AIBs are highlighted. Furthermore, future perspectives of AIBs are discussed.

Taking full advantage of the waste graphite from spent lithium-ion batteries (LIBs) to prepare the regenerate graphite anode and reuse it in lithium-ion batteries is a crucial strategy. Herein, we design a regeneration method involving pretreatment and an amorphous carbon layer coating to repair the defects of waste graphite. Specifically, through calcined in the air, sulfuric acid leaching, and amorphous carbon to modify the surface of graphite, the regenerated graphite not only has high purity but also can be reused as anode of LIBs. After two cycles of activation, the prepared graphite showed an excellent discharge specific capacity of 367.90 mAh g-1 at 0.1C. Besides, it also exhibits good cycling stability with a capacity retention of 83.24% after 350 cycles at 0.5C. Therefore, this work provides a valuable exploration for the cyclic utilization of waste graphite from spent lithium-ion batteries and demonstrates good economic and environmental benefits.

Due to its high availability, low cost, and outstanding electrochemical capabilities, CuFeS2 is a viable electrode material for lithium-ion batteries (LIBs). Its actual application is constrained, nonetheless, by substantial capacity fading and polysulfide production during the electrochemical process. To enhance the electrochemical characteristics and the chemical dissolution stability of the electrolyte, we present an optimal solvothermal synthesis of CuFeS2 with spherical morphology and high phase purify. The subsequent thermal pyrolysis with dopamine hydrochloride forms a uniform coating of N-doped carbon (NC) on the surface of CuFeS2 spheres. The successful NC coating increases the electronic conductivity of CuFeS2 and Li+ ion diffusion kinetics, and thus dramatically improves the rate and cycle performances of the constructed half cells and full LIBs. The ideal CuFeS2@NC with a 10 wt% NC anode demonstrates a reversible capacity of 878.6 mAh·g-1 at a current density of 0.5 C after 300 cycles, which is 93.4% of the initial capacity, and the coulombic efficiency remains above 98%. The fundamental charge and discharge mechanisms of CuFeS2@NC anodes are clarified by in situ electrochemical XRD analysis, and their primary mechanism for storing lithium is the “insertion-conversion” reaction.

Sulfur electrodes for lithium-sulfur batteries necessarily contain a conductive additive, typically carbon, to enable the electrochemical reactions, since sulfur and the discharge product, Li2S, are insulators. Consequently, the full passivation of carbon, by deposition of sulfur and/or Li2S, would necessarily produce the death of the battery. However, here we demonstrate that for high-performance lithium-sulfur batteries operated under lean electrolyte conditions (electrolyte to sulfur ratio of 6 mu L mg(S)(-1) in Li-S coin cells), the extent of passivation of carbon is not severe enough to limit performance. This is shown by performing impedance measurements of fully charged lithium-sulfur batteries, from which we demonstrate that we can evaluate the specific surface area of carbon, and we find that the capacity fade with cycling is not due to a decrease in the electrochemically active surface area of carbon. These results show that introducing a higher surface area carbon in the sulfur electrode formulation is not needed to prevent passivation, and that the focus of lithium-sulfur development should be directed towards other issues, such as mitigating undesirable reactions at the lithium electrode and achieving robust sulfur electrode structures enabling fast transport of electrolyte species and, thus, more homogeneous reactions. (c) 2021 Elsevier Ltd. All rights reserved.

We investigate the ground state properties of an ultracold atom system consisting of many-body polarons, quasiparticles formed by impurity atoms in optical lattices immersing in a Bose-Einstein condensate. We find the nearest-neighbor attractive interaction between polarons can give rise to rich physics that is peculiar to this system. In a relatively shallow optical lattice, the attractive interaction can drive the system being in a self-bound superfluid phase with its particle density distribution manifesting a self-concentrated structure. While in a relatively deep optical lattice, the attractive interaction can drive the system forming the Mott-insulator phase even though the global filling factor is not integer. Interestingly, in the Mott-insulator regime, the system can support a series of different Mott-insulators with their effective density manifesting a devil's staircase structure with respect to the strength of attractive interaction. Detailed estimation on relevant experimental parameters shows that these rich physics can be readily observed in current experimental setups.

We used the one-step hydrothermal controlled synthesis method for Co-Ni3S2 ultrathin nanosheets grown directly on nickel foam(NF). The as-synthesized Co-Ni3S2/NF showed enhanced activities in the hydrogen evolution reaction(HER), oxygen evolution reaction(OER) and better overall water splitting(OWS) efficiency than the un-doped Ni3S2/NF. The voltage of Co-Ni3S2/NF for OWS was only 1.58 V at the current density of 10 mA/cm2 and with long time(>30 h) current output during the current-density(i-t) test. The good i-t performance was also observed in both HER and OER processes. Additionally, the Co-Ni3S2/NF showed a large current density(>1 A/cm2) for both HER and OER. When the current densities reached 100 and 1000 mA/cm2, the required overpotentials for Co-Ni3S2/NF were 0.35 and 0.75 V for OER and 0.30 and 0.85 V for HER. Therefore, after introducing Co, th e activity of Ni3S2-based material was strongly enhanced.

Metal sulfides have been drawing more and more attention as electrode materials in batteries due to their high theoretical capacities. However, the volume expansion and loss of active materials are two major problems, hindering further improvement in their electrochemical performances. Herein, a strategy based on physical confinement/chemical adsorption is proposed to fabricate CoS and Co9S8 electrodes for advanced lithium batteries. Via a facile two-step method, porous C/CNT micro/nano-spheres embedding cobalt sulfide nanoparticles are successfully fabricated, in which sulfur is immobilized by CS bonds. Physically, the porous C/CNT micro/nano-spheres well accommodate the volume change and inhibit the loss of active materials. Chemically, the sulfur species are anchored by CS bonds to alleviate the migration and loss. Assembled as lithium battery anodes, the porous cobalt sulfide/carbon composites, particularly the CoS/C/CNT (CoS-0.4C) and Co9S8/C/CNT (Co9S8-0.8C), exhibit superior lithium storage properties to those without any complexing or any CS bonding. Furthermore, an in-situ electrochemical measurement is proposed to detect the existence of Li2S, which is helpful to understand the mechanism of conversion reaction-based metal sulfides.

Transition metal oxides and sulfides have been intensively investigated as host materials for the S cathode in Li-S batteries, however, the distinctions between them in battery operation have remained unclear. In this study, VO2 and VS2 nanosheets were systematically studied as host materials for Li-S batteries via theoretical calculations and experimental testing. First-principles calculations demonstrated that VS2 showed more favorable properties, including the inherent semimetallic conductivity of VS2, moderate adsorption strength for Li2Sn, fast Li+ transport with a low diffusion barrier, and accelerated surface redox reactions with a low Li2S decomposition barrier. In comparison, the low electronic conductivity and strong adsorption strength of VO2 increased Li+ diffusion as well as Li2S decomposition barriers of the electrode, resulting in relatively poor rate capability and cycle stability. In experiment, the VS2@S electrode exhibited superior electrochemical performance compared to VO2@S, for its large capacity of 713 mAh∙g-1 at 5C rate, and a low capacity fading rate of 0.13% per cycle in 200 cycles at 1C rate. The constructed relationships between S cathode and host materials could guide the future design of high performance S cathodes for Li-S batteries.

Ni3S2 nanosheets doped with tin (Sn) grown on nickel foam (Sn-Ni3S2/NF) through a facile hydrothermal process were found to be superior water-splitting electrocatalysts. As for overall water splitting (OWS), when the current density is 10 mA cm(-2), the required voltage is only 1.46 V. Meanwhile, it exhibits a large current density property and long-time stability (>60 h current-time tests) for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). In order to reach the current densities of 100 and 1000 mA cm(-2), Sn-Ni3S2/NF needs overpotentials of 0.17 and 0.57 V for HER, and 0.27 and 0.58 V for OER, respectively. The water-splitting property of Sn-Ni3S2/NF is much better than that of pure Ni3S2/NF or even 20 wt % Pt/C/NF and RuO2/NF. Furthermore, Sn-Ni3S2/NF showed a higher turnover frequency at different potentials, with similar to 100% Faraday efficiency for both O-2 and H-2. The improved activity of Sn-Ni3S2/NF activity for water-splitting is attributed to the doping of Sn, which enhanced the intrinsic activity of Sn-Ni3S2/NF for OWS. This article not only provides a new efficient and stable catalyst for OWS, but also proposes an interface design principle for NF-based high-performance water splitting materials.

The solution combustion synthesis (SCS) has been widely used to prepare varieties of materials, especially oxides. Nevertheless, there are just a few reports applying the SCS to synthesize sulfides, and most of them are prepared under the protection of an inert atmosphere. As the counterpart of metal oxides, the metal sulfides (MSs) also play an important role in energy-related devices. Herein, a novel air atmospheric SCS is proposed to prepare classes of MSs and the corresponding carbon composites. Thanks to the evaporation and flash burning of ethanol, the O2 is consumed, protecting the MSs and the carbon nanotubes (CNTs) from oxidation; thus, the mesoporous CoS, NiS, Cu2S, and the CoS/CNT, NiS/CNT, Cu2S/CNT, can be easily and rapidly obtained by directly combusting in the air atmosphere. Compared to the conventional SCS for synthesizing the MSs, the equipment requirements of this proposed method are low, which is suitable for large-scale preparation. The lithium storage properties of MSs and MSs/CNTs are investigated, in which the MSs/CNT composites show excellent lithium storage performances. This work provides a promising method to facilely prepare sulfides and their composites for energy-related systems.

With wide application of electric vehicles and large-scale in energy storage systems, the requirement of secondary batteries with higher power density and better safety gets urgent. Owing to the merits of high theoretical capacity, relatively low cost and suitable discharge voltage, much attention has been paid to the transition metal sulfides. Recently, a large amount of research papers have reported about the application of transition metal sulfides in lithium ion batteries. However, the practical application of transition metal sulfides is still impeded by their fast capacity fading and poor rate performance. More well-focused researches should be operated towards the commercialization of transition metal sulfides in lithium ion batteries. In this review, recent development of using transition metal sulfides such as copper sulfides, molybdenum sulfides, cobalt sulfides, and iron sulfides as electrode materials for lithium ion batteries is presented. In addition, the electrochemical reaction mechanisms and synthetic strategy of transition metal sulfides are briefly summarized. The critical issues, challenges, and perspectives providing a further understanding of the associated electrochemical processes are also discussed.

In this work, nonstoichiometric Cu2- xSe fabricated by a facile water evaporation process is used as high-performance Al-ion battery cathode materials. Cu2- xSe electrodes show high reversible capacity and excellent cycling stability, even at a high current density of 200 mA g-1, the specific charge capacity in the initial cycle is 241 mA h g-1 and maintains 100 mA h g-1 after 100 cycles with a Coulombic efficiency of 96.1%, showing good capacity retention. The prominent kinetics of Cu2- xSe electrodes is also revealed by the GITT, which is attributed to the ultrahigh electronic conductivity of the Cu2- xSe material. Most importantly, an extensive research is dedicated to investigating the detailed intercalation and de-intercalation of relatively large chloroaluminate anions into the cubic Cu2- xSe, which is conducive to better understand the reaction mechanism of the Al/Cu2- xSe battery.