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Novel sandwich-like porous carbon nanosheet-supported hexagonal carbon micro-flakes (WPWMC) are fabricated via a one-step hydrothermal route at 700 °C with polyethylene as the precursor and magnesium as the inducer. Through various characterizations, it is confirmed that the hexagonal carbon micro-flakes exhibit (002) orientation, which exposes abundant edge active sites and shortens the K+ transmission path. Moreover, the inside cross-linked carbon nanosheets with abundant pores can accelerate ion diffusion and increase the capacitive contribution. The WPWMC anode displays a high reversible capacity (528.7 mA h g−1 at 0.2 A g−1), good rate capability (152.7 mA h g−1 at 10 A g−1) and long-term cycle stability (112.1 mA h g−1 at 5 A g−1 after 10 000 cycles). Furthermore, the WPWMC//CMK-3 hybrid capacitor exhibits an energy density of 222.7 W h kg−1 at 446.2 W kg−1. This work provides an idea for transforming waste plastic into value-added materials. [ABSTRACT FROM AUTHOR]

Manganese oxides as cathode catalysts for lithium–oxygen batteries exhibit unsatisfactory oxygen catalytic activity and cycling stability, due to the weak adsorption of oxygen-containing intermediates and inevitable structural degradation caused by unstable high electron-density Mn sites. Herein, we rationally construct asymmetrical Mn–Ru dual sites on MnO2 nanowires to improve the catalytic activity and stability for Li–O2 batteries. Refined structural characterization proves that the Mn–Ru dual sites lead to an increase in electron density around the Mn site. Moreover, theoretical calculations reveal that the Ru single atom incorporation effectively decreases electron density in Mn–O antibonding states, thus stabilizing the high electron-density Mn sites while enhancing the adsorption of oxygen-containing intermediates. The obtained MnO2 nanowires with Mn–Ru dual sites display an overall discharge/charge overpotential (0.50 V) and an unprecedented cycling life (180 cycles or 1800 h), which is significantly superior to bare MnO2 and outperforms most of the ever-reported noble-metal-based cathodes. More importantly, the asymmetrical dual sites construction strategy can be readily expanded to Mn–Ir dual sites for enhancing the catalytic activity and stability of Mn-based catalysts. [ABSTRACT FROM AUTHOR]

Silicon monoxide (SiO) is a potential high-capacity anode material for lithium-ion batteries. The complexity of the lithiation process for SiO and challenges in the characterization of the lithiated products are fundamental aspects that underpin the discovery of the reaction mechanisms. In this work, we investigate the size-dependent (micro- and submicro-) electrochemical behaviors of SiO electrodes in terms of the irreversibility/reversibility of electrochemical lithiation/delithiation, interfacial/bulk stability, and interplay between SiO and graphite particles in the blended electrode. The irreversible Li+ consumption falls into three categories: O-participating electrochemical reactions of the Li–Si–O system, volume variation–induced inert LixSi alloy, and continued side reactions caused by the decomposition of the electrolyte. Reducing the particle size of SiO could hinder the formation of isolated inert LixSi alloys. However, the interfacial decomposition of the electrolyte is serious due to the high specific surface area. For the SiO/graphite blended electrode, it is confirmed that the graphite particles can buffer the volume change of SiO particles to some extent (<20 wt%), and the by-products of the SiO-related electrolyte decomposition would in turn hinder the lithiation/delithiation process of graphite particles. After decreasing the particle size of SiO, a more homogeneously distributed electrode is obtained and the cycling stability can be improved. [ABSTRACT FROM AUTHOR]

Uncontrollable lithium dendrite growth which typically results in poor cycling stability and safety issues remains a great challenge for lithium metal batteries. Herein, we report a novel separator modification strategy by using polydimethylsiloxane (PDMS) to functionalize a glass fiber separator to inhibit dendrite growth. The PDMS-modified separator not only acts as a mechanical barrier but also promotes the desolvation of lithium ions. Consequently, Li/Li symmetric cells with optimal PDMS-modified separators are able to stably cycle for more than 1200 hours at 2 mA cm−2 with a stable polarization voltage (about 60 mV). Moreover, with the assistance of the functionalized separator, the assembled Li/LiFePO4 full cell can impressively achieve capacity retention up to 82.5% and a coulombic efficiency of ∼99.4% after 200 cycles at 1.0 C. The PDMS functionalization strategy provides a simple and efficient approach for developing safe and high-performance lithium metal batteries. [ABSTRACT FROM AUTHOR]

Lithium–oxygen batteries with extra-high energy density have attracted increasing attention. However, their development is limited by sluggish oxygen redox kinetics, resulting in large overpotential and low cyclic life. Herein, N-NiCoO2/CoO arrays on conductive carbon cloth (noted as NNCO/CC) were designed by a hydrothermal and nitriding method as an ORR/OER bifunctional catalyst for LOB cathode to alleviate this problem. The introduction of N promotes electron redistribution on bimetal sites, which can enhance the affinity of intermediates (O*, LiO2*, Li2O2*) and induce the deposition/decomposition of flake-like amorphous Li2O2. Based on the NNCO/CC cathode, Li–O2 cells exhibit a low overpotential of 0.35 V and improved cycling capability of over 500 cycles at 0.05 mA cm−2. The cycle stability could be maintained over 225 cycles with a limited capacity of 0.2 mA h cm−2. DFT calculations further disclose that NNCO/CC shows a synergistic role in the ORR and OER processes. N-NiCoO2 has a more vital adsorption ability toward key intermediates (LiO2*) in the ORR process and N-CoO has a slight reaction energy barrier in the OER process. The method of regulating the electronic structure of bimetallic oxides to promote synergy in the redox reactions opens up new paths for the functional cathode design of Li–O2 cells. [ABSTRACT FROM AUTHOR]

Anode materials with a high initial coulombic efficiency and a long lifespan are highly desirable for sodium-ion batteries. Here, bimetallic μ-BiSn microspheres well combine the high capacity of Sn and the good stability of Bi together, exhibiting superior electrochemical performance, such as a high initial Coulombic efficiency (90.6%), a good cycling stability (541 mA h g−1 after 3000 cycles at 2 A g−1) and an excellent rate capability (393 mA h g−1 at 10 A g−1). [ABSTRACT FROM AUTHOR]

The binder chemistry in Na/K ion batteries is important to electrochemical performance. Here, commercial TiO2 nanoparticles are employed as a model to illustrate the binder chemistry in ethers, with polyvinylidene difluoride (PVdF) and sodium carboxymethyl cellulose (CMC) as the examples. An electrode using CMC as the binder shows superior electrochemical performance to that using PVdF, especially in terms of initial coulombic efficiency (80.1% for CMC vs. 52.5% for PVdF). The worse performance of the electrode using PVdF is mainly due to electrochemical defluorination of PVdF, which leads to cleavage of C–F and the formation of NaF over the electrode. Last but not least, a similar improvement in the binder chemistry works for many anode materials in Na/K-ion batteries. [ABSTRACT FROM AUTHOR]

Metal phosphides have exhibited great potential in the construction of highly efficient sulfur cathodes, benefiting from their high conductivity and catalytic property, which have been utilized to improve sulfur utilization, inhibit the drain of sulfur species during long-term cycling and facilitate the kinetics of the electrochemical reactions at the sulfur cathode of Li–S batteries. Here, porous polycrystalline NiCo2Px with an olivary morphology and robust structure has been fabricated via a facile derivation method. The NiCo2Px-derived sulfur cathode exhibited superior performance compared with the NiCo2O4 counterpart; besides high rate performance with a capacity of 610 mA h g−1 at 1C under an areal sulfur loading of 4.35 mg cm−2, areal capacity up to 8.54 mA h cm−2 was also achieved with high mass loadings of sulfur (5.79 mg cm−2) and a lean electrolyte (6 μL mg−1). The high conductivity and featured porous structure of NiCo2Px is considered to facilitate the electrochemical and kinetic behavior of the sulfur cathode, and its high catalytic activity was also preliminary established based on analyses of CV, EIS and symmetric batteries measurement. This work provides a new strategy for the fabrication of phosphides of elements in the iron family, broadens the application of metal phosphides in Li–S batteries, and deepens the understanding of the correlation between the morphology/phase structure of metal phosphides and the electrochemical performance of sulfur cathodes. [ABSTRACT FROM AUTHOR]

A series of phosphorus-doped hard carbon (PHC-Ts) was fabricated by directly annealing a phosphoric acid solidified epoxy resin over a wide temperature range to study the evolution of P-containing groups and the microstructure with increasing temperature, and to evaluate the Na-storage performance. A correlation between them has been well established. As the carbonization temperature increases, the P-containing groups undergo a transition from P–O and P–C bonds to higher active P–P bonds with a non-monotonic decrease in the interlayer distance. The high number of active P-containing groups and large interlayer distances provide more active sites and fast ion transmission channels, which jointly contribute to the excellent electrochemical performance. The obtained PHC-700 electrodes have the largest interlayer distance and highest total activity with many P–C bonds, showing a high capacity of 379.3 mA h g−1 at 0.1 A g−1, a superb rate capability of 158.1 mA h g−1 at 5.0 A g−1, and a long-term cycling stability without the loss of capacity after 6500 cycles at 5.0 A g−1. [ABSTRACT FROM AUTHOR]

Hollow nanospheres are desirable to resolve the volume expansion of red phosphorus anodes for sodium-ion batteries. Here, we developed a mild molten salt method to prepare hollow red phosphorus in the NaCl–KCl–AlCl3 system by using the Kirkendall effect. As an anode for sodium-ion batteries, the prepared hollow nanospheres exhibit a highly reversible capacity of 624 mA h g−1 at 4.0C and 737 mA h g−1 at 1.0C even after 600 cycles with a low capacity fading rate of 0.06% per cycle. [ABSTRACT FROM AUTHOR]

Aqueous sodium ion batteries (ASIBs) have been limited by their poor electrochemical stability. The use of highly concentrated aqueous electrolytes is considered as an efficient strategy that increases the voltage window and improves the cycling stability. However, their cost and safety are still subjects of serious concern for practical applications. In this work, we show that a new multi-component aqueous electrolyte (MCAE) could widen the voltage window to 2.8 V with the formation of a composite solvent sheath and promote the generation of a uniform solid electrolyte interface (SEI) layer consisting of complexes with inorganic salt Na2CO3 and other organic components, which significantly inhibits the side reaction. Thus, this MCAE guaranteed good electrochemical stability of Na3V2(PO4)3 and NaTi2(PO4)3, which suffer from severe performance degradation in aqueous electrolytes. Simultaneously, this MCAE exhibits high safety, a wide operating temperature range (−50 °C to 50 °C) and high ionic conductivity because of urea and N,N-dimethylformamide (DMF) additives. In addition, a nickel-based Prussian blue analog (NiHCF)/NaTi2(PO4)3 sodium-ion full battery using such a MCAE delivers 80% capacity retention after 2000 cycles at 2C rate. Moreover, our work provides important guidelines to investigate safe, environmentally friendly and high-stability ASIBs for large-scale energy storage. [ABSTRACT FROM AUTHOR]

The epitaxial deposition of solid sulfides prefers lateral deposition driven by the superior charge transfer of the conductive substrate to produce a continuous insulating 2D film. This situation not only disables the adsorbing host from controlling the dissolved PSs, but also terminates electrochemical redox when the mass transport and electron transfer are completely blocked by the non-conductive layer. Here, we present that single-atom Co is of significance to control the epitaxial deposition of solid sulfides to promote spherical cumulative deposition with 3D morphology. On the carbon paper (CP), the deposition shows the lateral deposition mode with a much lower capacity. On the single-atom Co decorated carbon paper (CoSAs-CP), it shows the spherical cumulative deposition mode with a high capacity reaching up to its theoretical value. The experimental studies and theoretical calculations reveal that single-atom Co can reconstruct the electronic structure of solid intermediates owing to the d–p hybridization associated with an electron feedback coupling mechanism, which benefits the non-locality of electrons and octahedron–tetrahedron fields of solid intermediates, promoting both the electron transfer and Li transport of longitudinal deposition to balance the lateral deposition so as to sustain the spherical epitaxial deposition. [ABSTRACT FROM AUTHOR]

An innovative and controllable silicothermic reduction is developed to prepare Si–Ge nanocrystals with the assistance of molten ZnCl2 at 450 °C, in which excess Si is explored as both the reductant and part of the target product, and a molten-salt medium can lower the reaction temperature. In situ reduction of GeO2 occurring on Si particles ensures the tight and uniform contact of residual Si and resulting Ge, forming an interconnected framework. The molar ratio of Si in all nanocrystals can be well controlled by varying the initial reactants. As the anode materials for lithium-ion batteries, the optimized Si–Ge nanocrystals exhibit impressive rate capability (a capacity of 866.8 mA h g−1 at 20 A g−1) and long cycling stability (a capacity of 1046 mA h g−1 at 2 A g−1 after 500 cycles). In situ Raman spectra, CV and GITT measurements demonstrate that the interconnected binary framework with Si and Ge nanocrystals facilitates the accommodation of volume change by step-by-step fast lithiation and improvement of the kinetic process in terms of overpotential and reaction resistance assisted by a conductive Ge component. Significantly, the silicothermic reduction is extended to produce other Si-containing functional materials or alloys such as Si–Sn, Si–Sb, Si–Bi, Si–Cu–Cu3Si, and Si–C via the reduction of various oxides or carbonates. This proposed silicothermic reduction system enriches the basic discipline of synthetic chemistry. [ABSTRACT FROM AUTHOR]

The lithium-sulfur battery has been considered as one of the potential candidates for energy storage devices owing to its high theoretical specific capacity and superior energy density. However, its practical application still faces challenges such as low sulfur utilization, the serious shuttle effect of polysulfides and large volume expansion, especially upon high areal sulfur loading. Herein, conductive cobalt doped niobium nitride (Co-NbN) porous spheres as a novel kind of sulfur host material have been fabricated via a facile solvothermal and subsequent calcination process under ammonia. The obtained Co-NbN/rGO/S cathode delivers an excellent rate performance of up to ∼600 mA h g−1 at 1C with a relatively high areal loading of 3.3 mgs cm−2 and an excellent long–term cycle stability of 404.5 mA h g−1 after 800 cycles at 1C (the decay rate is only 0.07% per cycle) with a sulfur loading of 72%. It is worth noting that the cathode exhibited a superior areal capacity of 3.92 mA h cm−2 at a high sulfur loading of 5.6 mgs cm−2 with a lean electrolyte (E/S = 8 μL mgsulfur−1). It is considered that the conductive and polar niobium nitride could effectively improve sulfur utilization and polysulfide anchoring of the sulfur cathode, and its unique porous structure could effectively accommodate the distribution of the sulfur species and inhibit volume expansion of the cathode. In addition, the synergistic effect between cobalt and NbN further facilitated the conversion of sulfur species, suppressing the shuttle effect and accelerating electrochemical kinetics. The porous Co-NbN based host material has great potential for practical application in lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries (LSBs) are considered to be promising candidates for use as energy storage systems owing to their high theoretical capacity and high energy density compared with high-level lithium-ion batteries. Despite these advantages, the commercialization of LSBs has been obstructed by certain deficiencies, such as the shuttle effect and poor conductivity of sulfur. On one hand, the chemical interactions between polar materials and lithium polysulfides (LPSs) have been investigated by researchers, particularly related to the shuttle effect. On the other hand, for improving the performance of LSBs, the conductivity of nonpolar materials has also received increased attention. Here, recent research advances involving polar and nonpolar materials for use in LSBs have been reviewed, particularly focusing on the polar interaction toward fixing LPSs, conductivity improvement, and electrochemical performance of LSBs. Subsequently, we have summarized and discussed a combination of polar and nonpolar materials for comprehensively promoting the performance of LSBs. In conclusion, the prospects and research directions for materials that can improve the cycle life and rate performance of LSBs have also been proposed. [ABSTRACT FROM AUTHOR]

Porous carbon materials have a broad range of potential applications, such as in electrochemical energy storage, filtration, catalysis, sensors, hydrogen storage, automobile exhaust treatment and so on. In this work, morphology evolution of metal–organic frameworks on a 3D metal substrate is explored via a simple binary-solvent method. With this rationally designed precursor, a graphene-like N-doped hierarchical porous carbon array on a 3D metal substrate (NPC/Cu) is obtained by a green and one-step vacuum de-metal assisted carbonization process. In situ-produced low boiling-point zinc elements can be evaporated and recycled during this process. The unique architecture where an N-doped porous carbon array is grown on a 3D metal substrate favors the graphitization degree and areal capacities of carbon anodes. When NPC/Cu is applied as a self-standing and binder-free anode for potassium-ion batteries (KIBs) in various electrolytes, an eminent electrochemical performance with a high reversible capacity of 315 mA h g−1 at 50 mA g−1 after 500 cycles, a superior rate performance of 120 mA h g−1 at 21C, and a relatively stable capacity of 129 mA h g−1 at 2000 mA g−1 after 20 000 cycles (corresponding to a capacity decay of only 0.0034% per cycle) can be obtained in a 5 M concentrated ether electrolyte. Furthermore, the superior electrochemical performance, outperforming that of most of the reported carbonaceous anodes for KIBs, can be attributed to the potassium storage mechanism dominated by capacitive-controlled behavior, proven by quantitative kinetics analysis. This work can shed some light on searching for carbon-based materials for KIBs and offer new insight to construct porous materials. [ABSTRACT FROM AUTHOR]

Lithium metal has long been recognized as the ultimate anode due to its low density, ultrahigh theoretical specific capacity, and lowest electrochemical potential. However, a number of issues, such as the uncontrollable growth of Li dendrites and unstable SEI during repeated Li plating/stripping processes, impede its practical application. Herein, uniform Li deposition on metallic current collectors was achieved via regulating the initial nucleation barrier by coating a thin 3 °C GaInSnZn liquid-metal layer on the surface. In the plating process of Li on liquid-metal-coated current collectors, a lithiation process initially occurred by the formation of a Li-rich alloy layer. As this Li-rich alloy layer was lithiophilic, the nucleation barrier was reduced, and Li was readily nucleated and uniformly grown on the alloy sites in the further plating process. As a result, liquid-metal-modified Cu foil exhibited improved coulombic efficiency and a smaller voltage fluctuation in the plating/stripping process. Better electrochemical performance was also demonstrated in full cells with LiFePO4 as the cathode. This work proposes a new and facile strategy for inducing the uniform deposition of Li, paving the way for the practical application of Li–metal anodes in high-energy-density Li–metal batteries. [ABSTRACT FROM AUTHOR]

Due to low cost, environmental friendliness, good safety, superior power density and ease of operation, rechargeable aqueous ion batteries can meet the technical requirements of large-scale energy storage. Compared with aqueous single ion batteries, rechargeable aqueous hybrid ion batteries (RAHBs) have been receiving extensive interest owing to their higher operating voltage and energy density. In this review, we briefly describe the developments and challenges of rechargeable aqueous ion batteries in energy storage and systematically introduce the merits and progress of various rechargeable aqueous hybrid ion batteries. The major issues of different combinations in aqueous hybrid ion batteries along with effective solving strategies are discussed, providing a new perspective for the design and construction of high performance aqueous ion batteries. Ultimately, the challenges and prospects of RAHBs are summarized for future research. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion batteries have shown great potential for grid-scale applications owing to their high safety, low cost and sustainability. However, they are still limited by the lack of suitable cathode materials with high energy density and satisfactory cycling stability. Herein, a highly reversible zinc-ion battery system with (NH4)2V6O16·1.5H2O nanobelts as the cathode materials and aqueous ZnSO4 solution as the electrolyte has been developed. The (NH4)2V6O16·1.5H2O nanobelts deliver a superior reversible specific capacity of 479 mA h g−1 at 0.1 A g−1 with a desirable energy density of 371.5 W h kg−1 and exhibit an impressive cycling stability, i.e. 152 mA h g−1 retained after 3000 cycles at 5 A g−1. The high energy density and long-term cycling stability make (NH4)2V6O16·1.5H2O a promising candidate for grid-scale energy storage. This work could be extended to choose and construct other ideal high-performance cathode materials for ZIBs and other multivalent metal ion storage systems. [ABSTRACT FROM AUTHOR]

An amine-induced phase transition strategy is developed for converting white phosphorus into red or black phosphorus. Amorphous red phosphorus is prepared through the chemical dissolution of white phosphorus in amines and post-treatment at room temperature. It is demonstrated that the phase transformation mechanism involves an amine-induced nucleophile attack on white phosphorus and the generation of polyphosphorus ions. The amorphous phosphorus exhibits a specific capacity of 955.5 mA h g−1 at 1.5 A g−1 after 1000 cycles, and a capacity retention of 1210.2 mA h g−1 even at 20 A g−1 for Li-ion batteries. This methodology is also applicable to produce red phosphorus micro-spheres and black phosphorus particles by varying the types of organic amines and the reaction temperature. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) have attracted increasing attention in the past two years. However, the lower intercalation-type capacity of the current graphite anode has limited the development of PIBs. Herein, we report a convention-alloying-type hollow Sb2Se3@C microtube prepared via a self-templated route by employing Sb2O3 microrods as the self-sacrificial templates. In situ Raman spectra investigation confirmed that the potassium storage mechanism of the Sb2Se3@C microtubes is the convention-alloying-type with the formation of K2Se in the first convention reaction process and K3Sb phase in the following alloying reaction stage. As an anode material for PIBs, the Sb2Se3@C microtubes exhibit a capacity of 312.8 mA h g−1 at 100 mA g−1 after 40 cycles, and a rate capability of 223.3 mA h g−1 at 1 A g−1. The capacity could be maintained at 191.4 mA h g−1 at 500 mA g−1 even after 400 cycles, suggesting that the carbon-supported hollow structure is in favor of enhanced potassium storage. [ABSTRACT FROM AUTHOR]

Although Ni3N possesses superior hydrogen desorption behavior, its alkaline hydrogen evolution reaction (HER) catalysis is substantially hindered, due to the high-lying unoccupied orbital center induced sluggish water dissociation kinetics. Herein, we successfully endow Ni3N with exceptional alkaline HER activity by in situ interfacial engineering. The prepared Ni3N/MoO2 interfacial system delivers an ultra-small overpotential of 21 mV at 10 mA cm−2, which is very close to that of the benchmark Pt/C catalysts. Density functional theory (DFT) calculations reveal that MoO2 with a lower unoccupied orbital center could substantially boost the water dissociation kinetics, while the hydrogen desorption proceeds on Ni3N. The capability to understand and design interfacial systems provides an effective pathway for the rational construction of HER catalysts and beyond. [ABSTRACT FROM AUTHOR]

Metal-based anode materials such as Sb, Sn, Bi, etc., attract great attention for battery use due to their high electronic conductivity and high energy density. However, the large volume expansion during the alloying–dealloying process results in fast performance decay. In this work, we successfully grow hierarchical Sb, Sn and Bi firmly on MXene paper via a facile one-step electrodeposition process in a green ethylene glycol-based system. As robust, flexible, free-standing and binder-free anodes for potassium-ion batteries, the hierarchical structure provides a short diffusion distance for potassium ions and buffer volume change during the potassiation/depotassiation process. Highly conductive and flexible MXene paper serves as an elastic current collector providing an electronic highway to facilitate electron transport and accommodate volume change during the cycling process. MXene@Sb delivers a high reversible capacity of 516.8 mA h g−1, a high rate capacity of 270 mA h g−1 at 500 mA g−1, and stable capacity retention with a capacity fading rate of only 0.042% per cycle. This work may also be interesting in relation to research on other rechargeable batteries, catalysts, sensors, etc. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanomaterials with a high specific surface area and mesoporous nature are attractive and have wide applications in catalysis, energy storage systems, etc. Here, we report a novel strategy to fabricate noble metal-free, F-doped α-Ni(OH)2 mesoporous 2D ultrathin nanosheets. The F-doped α-Ni(OH)2 nanosheets exhibit remarkable electrocatalytic activity and stability for the oxygen evolution reaction, achieving a low onset potential (260 mV), high mass activity (69.1 A g−1 at η = 350 mV) and low Tafel slope (31.89 mV dec−1), which are superior to those of commercial RuO2 catalysts. Simultaneously, F-doped α-Ni(OH)2 nanosheets are found to have a high specific capacitance of 158.75 F g−1 at 1 A g−1 with a maximum energy density of 67.4 W h kg−1 at a power density of 400 W kg−1, which could still retain 40 W h kg−1 at a power density of 16 kW kg−1. DFT calculations rationalize that F doped α-Ni(OH)2 favors electrical conductivity, efficient electron transport and water adsorption. It could be envisioned that the proposed simple and efficient approach will pave a new way to synthesize other anion doped 2D materials for energy conversion and storage technology. [ABSTRACT FROM AUTHOR]

The lithium anode exhibits promising prospects for application in next-generation batteries. Herein, acetylene black and N-doped carbon submicrospheres were simply mixed, leading to their significantly improved electrochemical performances. This result can be attributed to the synergistic effect of good lithiophilic surface and high electron conductivity. [ABSTRACT FROM AUTHOR]

Storage technology of electrical energy with ultrafast charge/discharge rates is in high demand for future electronics and electric vehicles. Among them, sodium ion batteries (SIBs) have received much attention, however, the exploration of electrode materials with a high rate capacity and long cycle life still faces great challenges. In this work, we have fabricated coralloid NixCo1−xSe2 with a hierarchical architecture for the first time, and it presents specific capacities of 321 mA h g−1 after 2000 cycles at 2 A g−1, corresponding to a capacity decay rate of 0.011% per-cycle, and 277 mA h g−1 even at the high rate of 15 A g−1, which could be attributed to the enhanced conductivity by Co-doping, the hierarchical architecture preventing the structure from collapsing or crushing, the accelerated electron transmission and the shortened diffusion distance of Na+. The extremely fast electron and Na ion transfer kinetics could be associated with the capacitive contribution. We further reveal the ultrastable and ultrahigh rate Na-ion storage mechanism through systematic analysis including compositional/structure evolution studies and comprehensive electrochemical characterizations. The presented strategy for the design and synthesis of coralloid, Co doped NiSe2 with a hierarchical architecture could enlighten researchers on the development of electrodes with an ultralong cycle life and ultrahigh rate capability. [ABSTRACT FROM AUTHOR]

In this work, carbon nanotube-coated dual-shell Co9S8 hollow spheres are studied as anode materials for K-ion batteries. The unique hollow structure and carbon nanotubes synergistically enhance the conductivity and resolve the critical drawbacks of Co9S8 electrodes, including large volume variation, structural instability and interfacial changes. Thus, the electrode delivers a stable reversible capacity of 320.5 mA h g−1 at 0.1 A g−1 after 200 cycles with a capacity retention of 91%. At 1.0 A g−1, the capacity is 163.9 mA h g−1 after 1000 cycles with a capacity retention of 73.6%. An investigation of the electrode reaction mechanism indicates that the surface capacity also contributes to the outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

Hard carbon has been identified as a promising anode material for sodium-ion batteries (SIBs). Herein, a facile self-templating strategy has been developed for the kilogram-scale preparation of N,O-codoped hierarchical porous hard carbon cuttlefish-like nanowire bundles (denoted as NOHPHC cuttlefishes). The unique nanoarchitecture leads to ultrafast pseudocapacitive sodium storage, excellent reversibility, and negligible degradation of the host material. NOHPHC delivers a high reversible capacity of 184 mA h g−1 at 0.5 A g−1, which is maintained at 114 mA h g−1 at 5 A g−1 for over 30 000 cycles, as well as exceptional rate capability of up to 20 A g−1 with a capacity of approximately 100 mA h g−1. Importantly, samples prepared before and after kilogram scaling are comparable in performance. Coupled with a Na3V2(PO4)3/C cathode, a full cell successfully obtains a high energy density of 52.6 W h kg−1 at 50 W kg−1 and 34 W h kg−1 at 1.4 kW kg−1. [ABSTRACT FROM AUTHOR]

Lithium metal has been regarded as an ideal anode material for high-energy-density batteries. However, its high chemical reactivity, virtually infinite volume change and dendrite growth greatly reduce coulombic efficiency and increase potential safety hazards, thereby limiting its practical performance. Here, Li3P/LiCl-coated Li was successfully prepared by a simple reaction between PCl3 and Li at room temperature. Li3P, as a Li-ion conductor, reduces interface impedance and improves the electrochemical kinetics. LiCl, as the minor phase, enhances Li diffusion at the interfaces and reinforces the Li metal protection together with Li3P, suppressing the formation of Li dendrites. Thus, cycle stability and rate capability are greatly improved, as demonstrated both in symmetric cells and in the Li//LiCoO2 and Li//S full cells. [ABSTRACT FROM AUTHOR]

In a simple and convenient way, mesoporous germanium nanoparticles (mp-Ge NPs) are prepared by a “metathesis” reaction of magnesium germanide (Mg2Ge) and zinc chloride (ZnCl2) in an autoclave at 300 °C. Investigated as anode materials for lithium-ion batteries, the prepared mp-Ge NPs exhibit a high capacity retention of 1048 mA h g−1 at 1 C after 1000 cycles and a high rate capacity of 727.1 mA h g−1 at 10 C in Li–Ge half cells. Additionally, a 3.4 V lithium-ion full cell (Ge-LiCoO2) with an energy retention of 85% (∼268.8 W h kg−1) over 100 cycles is achieved. [ABSTRACT FROM AUTHOR]

In this work, we have developed a simple and facile method to synchronously synthesize hollow FeSe2/C nanospheres using the Kirkendall effect. When evaluated as an anode for SIBs, the hollow FeSe2/C nanospheres exhibit a high discharge capacity retention of 474.1 mA h g−1 at 0.05 A g−1 (based on the calculation of FeSe2), which is very close to the theoretical capacity of FeSe2 (∼500 mA h g−1). Meanwhile, hollow FeSe2/C also has a superior rate capability of 364.5 and 316.5 mA h g−1 even at 2.0 and 5.0 A g−1, respectively. The high performance of the hollow FeSe2/C nanospheres can be ascribed to the unique carbon coated hollow nanostructure. [ABSTRACT FROM AUTHOR]