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CuS nanospheres interconnected by the carbon nanotubes (CNTs) have been successfully prepared via a facile one-step microwave-assisted method. The component and microstructure of CuS/CNTs hybrid materials are well characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). Assembled as electrodes and tested in lithium ion batteries, the composites show impressive electrochemical performances. After 450 cycles, the CuS/0.1 CNT and CuS/0.5 CNT release more than 437 and 569 mAh g−1, respectively, at 400 mA g−1, which are superior to those of contrast experiments (pristine CuS and CuS mechanically mixing with CNTs). Even at the high current density of 6400 mA g−1, the CuS/0.5 CNT still displays the reversible capacity of about 400 mAh g−1. The improved performances can be ascribed to the inherently CNTs conducting network, boosting the interior electron transport and reaction kinetics, so that a significantly enhanced reversible capacities and rate capability can be realized. Furthermore, the surface properties and reaction kinetics of electrodes are also investigated via cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced lithium storage properties.

A flexible SiO2 porous fiber membrane (SF) is prepared by electrospinning followed by calcination in this work. Compared with an organic substrate separator, the SF used as a separator will be an absolute guarantee of the battery thermal safety. The porosity of the SF is 88.6%, which is more than twice that of a regular PP separator. Hydrophilic SF shows better electrolyte wetting ability and its high porosity enables the SF to absorb 633% liquid electrolyte on average, while the lithium-ion conductivity reaches 1.53 mS cm−1. The linear sweep voltammogram testing of PP and SF suggested that SF, with great electrochemical stability, can meet the requirements of lithium-ion batteries. The cyclic and rate performances of batteries prepared with SF are improved significantly. Such advantages of the SF, together with its potential in mass production, make the SF a promising membrane for practical applications in secondary lithium-ion batteries.

A hard carbon sheet-like structure has been successfully prepared with a short flow process by simply using cherry petals (CPs) as the raw materials. The sodium storage mechanism in CPs was detected with cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). Encouragingly, when being assessed as an anode electrode for sodium-ion batteries (SIBs), the CP electrode can provide a high initial reversible capacity of 310.2 mA h g−1 with a favorable initial Coulomb efficiency of 67.3%, delivering a high retention rate of 99.3% at 20 mA g−1 after 100 cycles. Even at a high current density of 500 mA g−1, the reversible capacity can reach 146.5 mA h g−1, indicating that the high rate performance is excellent as well. Such a preferable performance may be derived from the prepared structures with sufficient mesopores, the presence of nitrogen/oxygen functional groups on the surface and the expanded interlayer distances (∼0.44 nm), which enable reversible sodium-ion storage through surface adsorption and sodium intercalation.

We report a rational design of vapor grown carbon fiber (VGCF) 3D conducting host coating on a glass fiber filter for its use as a lithium metal anode to inhibit dendrite growth and enhance cycling stability. The high coulombic efficiency of 91.1% and stable cycling can be maintained after 100 cycles (965 h) at the current density of 0.5 mA cm−2 for the capacity of 2.5 mAh cm−2 in the carbonate electrolyte.

Unstable solid electrolyte interphase between lithium metal and electrolyte results in low coulombic efficiency and limited cycle life, which hinder the utility of lithium metal anode. Besides, how to settle the cathode material corrosion in practical lithium metal batteries is also a key challenge. Here, lithium 2 trifluoromethyl-4,5-dicyanoimidazolide (C6F3LiN4) is reported as valid electrolyte additive for bi-electrode protective films formation in practical Li metal-based batteries. The C6F3LiN4 plays distinct functions in bi-electrode interface, it attributes to robust F, N-rich polymer interphase layer on the cathode which effectively protect the cathode from deterioration. And it promotes the even distribution of LiF and polycarbonate species on anode and prevent the formation of Li dendrites. The symmetric cell of C6F3LiN4 exhibits stable cycling performance with 1 mA cm−2 (700 h). In addition, the improvement in the Li metal deposition uniformity has been confirmed by atomic force microscope and simulation. Benefiting from the synergistic enhanced stability and uniformity of electrode interphase, the LiNi0.5Co0.2Mn0.3O2 || Li metal battery with C6F3LiN4 can maintain high capacity retention of 82.6% after 400 cycles. Importantly, the Li metal pouch battery pairing high-loading cathode (16.12 mg cm−2) also deliver longer cycle life, validating its feasibility in practical applications.

Silicon has been considered as the most promising anode candidate of new generation high-performance LIBs, but the huge volume strain during cycling processes limited its practical applications. Herein, the binder free TiO2-nanowires (NWs)-C/Si/C 3D network composite has been prepared by chemical vapor deposition (CVD) and facile carbonization process as a great solution to the problem. In this composite, the intertwined TiO2-NWs serves as a buffer matrix to alleviate the volume strain of silicon during cycling processes, while the dual protective carbon layers enhance the conductivity of TiO2-NWs and prevent Si from peeling off the substrate. The as-prepared TiO2-NWs-C/Si/C anode shows great cycling performance with a reversible capacity of 1570 mAh g−1 at 2 A g−1 and excellent capacity retention of 85.7% up to 100 cycles.

Lithium sulfur batteries have been widely studied because of their high energy density. However, their commercialization has been impeded by several problems, such as the poor conductivity of the active material sulfur and its discharge products, the volume expansion and the shuttle effect caused by the polysulfide intermediates dissolving in organic electrolytes. To address these problems well, we have constructed high sulfur content spherical sulfur-carbon nanotube-polyethylene glycol-nickel nitrate hydroxide (SCNT-PEG-NNH) composite material by using a simple ball-milling method. The conductivity of the composite material gets improvement due to the spherical conductive frame constructed by CNT, while the shuttle effect of polysulfides is well inhibited by the wrapping of the PEG and the fixation of NNH. The results of electrochemical tests have shown that the performance of cathode made by the SCNT-PEG-NNH composite material is greatly improved. Therefore, the SCNT-PEG-NNH composite material can be a promising cathode material for lithium sulfur batteries.

Further improving the energy density of batteries is the development theme and trend of lithium ion batteries for vehicle, and key materials lay the foundation for better batteries. This review covers scientific challenges and development trends for Li-ion batteries and their key materials, such as cathode, anode, electrolytes and separator. Developing novel cathode materials with high voltage and high capacity has become the main approach to increase the specific energy of lithium ion batteries. The anode materials will continuously develop towards low cost, high specific energy and high safety, and it becomes a consensus that silicon-based composites are very promising anode materials for boosting the energy density of lithium-ion batteries. In addition, this review analyzes the key technologies of lithium ion batteries, such as the materials selection and matching, battery safety and battery manufacturing process, and puts forward the fundamental scientific problems should be concerned in the study of lithium ion battery.

The lack of suitable high-voltage cathode materials has hindered the development of rechargeable magnesium batteries (RMBs). Here, mesoporous Na3V2(PO4)3/C (NVP/C) spheres have been synthesized through a facile spray-drying–annealing method, and their electrochemically desodiated phase NaV2(PO4)3/C (ED-NVP/C) has been investigated as an intercalation host for Mg2+ ions. The obtained ED-NVP/C exhibits an average discharge voltage of around 2.5 V (vs. Mg2+/Mg), higher than those of most previously reported cathode materials. In addition, it can deliver an initial discharge capacity of 88.8 mA h g−1 at 20 mA g−1, with good cycling stability. Ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results demonstrate that the electrochemical reaction is based on an intercalation mechanism and shows good reversibility. Galvanostatic intermittent titration technique (GITT) data have revealed that the intercalation process involves a two-phase transition. The reported ED-NVP/C cathode material with high working voltage offers promising potential for application in RMBs.

Although lithium-sulfur batteries are considered as promising high-energy-storage system owing to their high energy density, developing effective materials to host sulfur species on the cathode is still challenging. Herein, an inexpensive and effective carbon precursor, catechol and polyamine is explored to fabricate nitrogen/oxygen dual-doped hollow carbon nanospheres (DHCSs) as sulfur hosts. The group containing nitrogen and oxygen can provide stronger chemisorption for lithium polysulfides than single-doped carbon matrix, which is confirmed by X-ray photoelectron spectroscopy analysis and the theoretical calculation. As a result, the designed sulfur/DHCSs cathode delivers a stable cycling performance remained 851 mAh g −1 discharge capacity at 0.2 C with ∼0.08% capacity decay per cycle after 200 cycles, revealing its great promise for energy storage application.

Si is regarded as a promising anode candidate for lithium-ion batteries (LIBs) due to its high theoretical capacity and appropriate Li + ions insertion voltage ( + /Li). However, its intrinsic inferior electronic conductivity and huge volume changes during cycling lead to poor cyclic performance. Integrating Si with carbon materials has been proved to be an efficient route to improve its electrochemical performance. In this report, we successfully synthesized Si-reduced graphene oxide-amorphous carbon (Si-rGO-C) composite assisted with a facile guar gum hydrogel method and studied the protective effect of different kinds of carbon. In the Si-rGO-C ternary composite, the Si nanoparticles (NPs) are embedded in amorphous carbon and tightly anchored to rGO sheets. The amorphous carbon and rGO serve as synergistic protective layers. The Si-rGO-C composite possesses good structural integrity accompanied by enhanced conductive framework. The resulting Si-rGO-C composite exhibits much improved electrochemical performance (a high capacity of 913 mAh g −1 can be maintained after 100 cycles at 0.5 A g −1 with almost no capacity decay) compared with the Si-rGO and Si-C composites with only single protective layer, indicating the importance of constructing synergistic carbon layers in Si-rGO-C ternary composite for LIB anodes.

The catalytic activity and stability of electrocatalyst is critical for the commercialization of fuel cells, and recent reports reveal the great potential of the hollow structures with Pt skin coat for developing high-powered electrocatalysts due to their highly efficient utilization of the Pt atoms. Here, we provide a novel strategy to prepare the Pt skin coated hollow Ag-Pt structure (Ag-Pt@Pt) of ∼8 nm size at room temperature. As loaded on the graphene, the Ag-Pt@Pt exhibits a remarkable mass activity of 0.864 A/mgPt (at 0.9 V, vs. reversible hydrogen electrode (RHE)) towards oxygen reduction reaction (ORR), which is 5.30 times of the commercial Pt/C catalyst, and the Ag-Pt@Pt also shows a better stability during the ORR catalytic process. The mechanism of this significant enhancement can be attributed to the higher Pt utilization and the unique Pt on Ag-Pt surface structure, which is confirmed by the density functional theory (DFT) calculations and other characterization methods. In conclusion, this original work offers a low-cost and environment-friendly method to prepare a high active electrocatalyst with cheaper price, and this work also discloses the correlation between surface structures and ORR catalytic activity for the hollow structures with Pt skin coat, which can be instructive for designing novel advanced electrocatalysts for fuel cells.

Co3O4 is emerging as a promising anode candidate for lithium ion batteries (LIBs) with high theoretical capacity (890 mAh g–1) but suffers from poor electrochemical cycling stability resulting from the inferior intrinsic electronic conductivity and large volume changes during electrochemical cycling. Here, a new electrophoretic deposition Co3O4/graphene (EPD Co3O4/G) hybrid electrode is developed to improve the electrochemical performance. Through EPD, Co3O4 nanocubes can be homogeneously embedded between graphene sheets to form a sandwich-like structure. Owing to the excellent flexibility of graphene and a large number of voids in this sandwich-like structure, the structural integrity and unobstructed conductive network can be maintained during cycling. Moreover, the electrode kinetics has proved to be a fast surface-controlled lithium storage process. As a result, the Co3O4/G hybrid electrode exhibits high specific capacity and excellent electrochemical cycling performance. The Co3O4/G hybrid electrode ...

The high-temperature and high-humidity storage behaviors and electrochemical degradation mechanism of LiNi0.6Co0.2Mn0.2O2 cathode material are investigated systematically. After stored at 55 °C and 80% relative humidity, three kinds of changes are observed compared to the fresh materials. The first change is adsorbed species on the surface of the materials caused by atmospheric H2O and CO2. The second is a layer of impurities consisting of LiOH and Li2CO3 coated on the surface of the materials non-uniformly. The third is a delithiation layer directly contacting with the bulk materials in the near-surface region, which is believed to be formed by lithium-ions migrating out from the lattice accompanied by the generation of the impurities. A different combination of heating temperature, heating time and heating atmosphere is performed to achieve the separation of the adsorbed species and the delithiation layer (together with the impurities) and study the role of different part in electrochemical degradation, respectively. For the first and the following cycles, the effect of the adsorbed species on the electrochemical properties takes a larger proportion than that of the delithiation layer and impurities.

Li3VO4/C/rGO (HC-LVO/C/G) ternary composite with honeycomb-like structure is successfully prepared through a simple spray drying method with polystyrene (PS) microspheres as soft template. In this characteristic structure, carbon-coated Li3VO4 nanoparticles are well wrapped by rGO sheets and uniformly distributed within the honeycomb-like micrometer-sized clusters. The double coating layers of amorphous carbon and rGO can avoid the direct exposure of Li3VO4 nanoparticles to the electrolyte and enhance the electronic conductivity. Meanwhile, the honeycomb-like structure can shorten the diffusion paths of Li+ ions and favors the relaxation of the strain/stress during cycling. The resultant HC-LVO/C/G composite exhibits significantly improved high-rate performance and long cycle-life (the high reversible capacity of 312 mAh g−1 can be maintained after 1000 cycles at 10 C) compared with the contrastive Li3VO4/C composite synthesized by a typical solid-state reaction method.

In this work, CuS microspheres are synthesized by a facile microwave synthesis without any template or additive. As-prepared CuS microspheres display steady reversibility by adopting triethylene glycol dimethyl ether (TEGDME) as the electrolyte solvent and adjusting cut-off voltage to 0.6 − 3.0 V. The discharge capacity stands at 162 mAh g −1 after 200 cycles with the capacity retention of 95.8%. Electrochemical kinetics of CuS electrodes is investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) tests. Beyond that, electrochemical reactions of CuS electrodes are explored using ex-situ X-ray diffraction (XRD). As far as we know, it is not only the best performance of CuS electrodes in Na-ion batteries (NIBs) but also the first time that the kinetics and reaction mechanism of CuS in NIBs are investigated.

Li3VO4 (LVO) is a promising insertion-type anode material for lithium ion batteries (LIBs) while its electrochemical performance in magnesium ion batteries (MIBs) is rarely reported. Here, mesoporous LVO/Carbon (LVO/C) hollow spheres are synthesized by a facile spray-drying method and their electrochemical performance as Mg2+ insertion-host material is investigated for the first time. Galvanostatic charge-discharge results of LVO/C show no obvious platform in the potential range of 0.5∼2.5 V vs. Mg2+/Mg. The LVO/C delivers a high discharge capacity of 318 mAh g−1 at first cycle and exhibits good cycle performance. The electrochemical intercalation process is proved by element mapping, ex-situ X-ray Powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Our results show that LVO is a promising anode material for MIBs.

Nanostructure construction and surface modification are effective ways to improve the electrochemical performances of electrode materials, especially for the conversion reaction-based materials. In this study, one-dimensional carbon coating bamboo-like Cu 2-x S nanorods have been delicately designed in a template-free method. The structure and morphology are well characterized via different instruments such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tested in lithium batteries as the anode, the Cu 2-x S@C electrode shows superior electrochemical performances to pristine Cu 2-x S. At 1 and 2 C, the Cu 2-x S@C nanorod electrode releases 309 and 277 mAh g −1 after 300 cycles. At high rates of 15 and 22 C, the electrode still exhibits 269 and 264 mAh g −1 . The kinetics of electrodes are also investigated by means of cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced electrochemical properties. Thus, the one-dimensional bamboo-like Cu 2-x S voided nanorods can be a promising candidate for high-performance batteries.

The lithium-sulfur battery is considered as a prospective candidate for a high-energy-storage system because of its high theoretical specific capacity and energy. However, the dissolution and shutter of polysulfides lead to low active material utilization and fast capacity fading. Electrospinning technology is employed to directly coat an interlayer composed of polyacrylonitrile (PAN) and nitrogen-doped carbon black (NC) fibers on the cathode. Benefiting from electrospinning technology, the PAN-NC fibers possess good electrolyte infiltration for fast lithium-ion transport and great flexibility for adhering on the cathode. The NC particles provide good affinity for polysufides and great conductivity. Thus, the polysulfides can be trapped on the cathode and reutilized well. As a result, the PAN-NC-coated sulfur cathode (PAN-NC@cathode) exhibits the initial discharge capacity of 1279 mAh g-1 and maintains the reversible capacity of 1030 mAh g-1 with capacity fading of 0.05% per cycle at 200 mA g-1 after 100 cycles. Adopting electrospinning to directly form fibers on the cathode shows a promising application.

The Li3VO4@C microsphere composite was first reported as a novel cathode material for rechargeable aluminum-ion batteries (AIBs), which manifests the initial discharge capacity of 137 mAh g–1 and and remains at 48 mAh g–1 after 100 cycles with almost 100% Coulombic efficiency. The detailed intercalation mechanism of Al into the orthorhombic Li3VO4 is investigated by ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) of Li3VO4@C electrodes and the nuclear magnetic resonance aluminum spectroscopy (27Al NMR) of ionic liquid electrolytes in different discharge/charge states. First-principle calculations are also carried out to investigate the structural change as Al inserts into the framework of Li3VO4. It is revealed that the Al/Li3VO4@C battery goes through electrochemical dissolution and deposition of metallic aluminum in the anode, as well as the insertion and deinsertion of Al3+ cations in the cathode in the meantime. The rechargeable AIBs fabricated in this work are of low cost a...

Transport infrastructure development is generally perceived as catalyst for economic growth. This has been highlighted in previous literature, generally focusing on the economic impact of transport infrastructure investments. This paper contributes to spatial econometrics by examining the causal relationship between economic strength and accessibility gains due to the development of expressways and high-speed rail, taking the Yangtze River Delta as research object. Spatial regression models that accommodate for the influence of spatial autocorrelation and the newly defined variable “weighted mode's average travel time (WMATT)” and other explanatory variables are developed for quantitative analysis. Estimation results indicate that cities' gross domestic product increases significantly with population, passenger traffic, and foreign direct investment. Especially, all the estimated models indicate that WMATT is significantly and negatively associated with gross domestic product, revealing that inter-city accessibility gains (travel-time savings) can enhance economic strength. The robustness analysis on the estimators indicates that while the β -coefficient of WMATT generally increases with the share of expressways and high-speed rail in land transportation, its p -value increases and its effect may become insignificant if inter-city travel time becomes fast enough. Findings from this study highlight the travel-speed up measures such as open China's expressway freely and speed up the high-speed rail rather than blind development and endless investments can also play an important role in enhancing economic strength.

In this work, NaFeTi3O8 with three-dimensional porous net-like sheet morphology is firstly prepared by a simple and effective solution combustion method. Encouragingly, when being assessed as an anode electrode for sodium ion batteries, the NaFeTi3O8 net-like sheet composite exhibits superior electrochemical properties. We also study the effect of the combustion fuel glycine. The results indicate that the NaFeTi3O8 composite tends to be porous with glycine as the combustion fuel, which displays more excellent long cyclic stability (discharge capacity of 91 mA h g−1 after 1000 cycles at the current density of 0.5 A g−1) and superior rate performance (84.4 mA h g−1 even at 1.6 A g−1) than that of NaFeTi3O8 without glycine as the combustion agent. The enhanced electrochemical properties could be ascribed to the unique porous morphology, which achieves better electrolyte infiltration and faster ion diffusion.

The thermal stabilities of delithiated LiNi 0.5 Co 0.2 Mn 0.3 O 2 (L523), delithiated LiMn 2 O 4 (LMO), and delithiated LiFePO 4 (LFP) for lithium ion batteries with bare electrode, solvent and different concentration of electrolyte under delithiated state have been investigated by using differential scanning calorimetry (DSC) and ex X-ray diffraction (XRD). The LFP has the best thermal stability, follows by the LMO and then the L523. The existing of solvent facilitates the decomposition of materials. The addition of Li salt in solvent can further accelerate the thermal decomposition of LMO and LFP; but hold back the decomposition of L523 at some extent that although the total reaction heat grown by 297 J g −1 , the first exothermic peak (ca. 279 °C) moves backwards comparing with L523 and solvent coexisting system (ca. 255.7 °C). As increasing the ratio of electrode material quality to electrolyte, the total exothermic quantity of L523 and LMO becomes large, meanwhile the unit mass exothermic quantity of the L523 varies with little dropping tendency, and that of the LMO decreases obviously. However, for the LFP, the total exothermic quantity decreases and the unit mass exothermic quantity decreases more obviously. Also, the XRD patterns of the three samples at ambient temperature and after 350 °C processing with existing of solvent or electrolyte suggest that the L532, LMO and LFP suffer evident structure changes since their pristine peaks become broader, weaker and splitting or disappearing at high temperature.

Owing to their unique structural stability and impressive long-term cycling performance, coated hollow structures are highly attractive for energy storage systems, especially batteries. Many efforts have been devoted and various strategies have been proposed to prepare such materials. In the present work, we propose a self-templating thermolysis strategy, different from traditional wet processing methods, to fabricate cuprous sulfide hollow spheres coated with different shells, by exploiting the thermal decomposition properties of the core (CuS) and the protection provided by the shell. To demonstrate the generality of this synthetic approach, three different coating materials (carbon, TiO2, MoS2) have been chosen to prepare Cu2–xS@C, Cu2–xS@TiO2 and Cu2–xS@MoS2 hollow spheres. All synthesized composite materials were then assembled as electrodes and tested in lithium batteries, showing excellent cycling stability. In particular, the electrochemical properties of Cu2–xS@C were thoroughly investigated. The results of this work provide an alternative route to prepare coated metal sulfide hollow spheres for energy storage applications.

A new type of single-ion conducting polymer electrolyte, poly(hexafluorobutyl methacrylate-co-lithium allyl sulfonate) (P (HFMA-co-ASLi)) for lithium-ion batteries, was firstly prepared by copolymerizing hexafluorobutyl methacrylate (HFMA) and sodium allyl sulfonate (SAS) with a subsequent lithiation process. The prepared polymer electrolyte exhibits high lithium ionic conductivity (10-4 S cm-1 at 80 ℃) and excellent cycle performance at high temperature, which could be attributed to the good thermal stability (remains stable up to 300 ℃), mechanical property (7.1 MPa for breaking strength) and high lithium-ion transference number (0.92). The electrolyte also displays good electrochemical stability (4.6 V). Our obtained results prove that the polymer P (HFMA-co-ASLi) is a promising candidate electrolyte for lithium-ion batteries.

A rod-like Cu2−xSe is synthesized by a facile water evaporation process. The electrochemical reaction mechanism is investigated by ex situ X-ray diffraction (XRD). By adopting an ether-based electrolyte instead of a carbonate-based electrolyte, the electrochemical performance of Cu2−xSe electrodes improved significantly. The Cu2−xSe electrodes exhibit outstanding cycle performance: after 1000 cycles, 160 mA h g−1 can be maintained with a retention of 80.3 %. At current densities of 100, 200, 500, and 1000 mA g−1, the capacity of a Cu2−xSe/Li battery was 208, 202, 200, and 198 mA h g−1, respectively, showing excellent rate capability. The 4-probe conductivity measurements along with electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV) tests illustrate that the Cu2−xSe electrodes display high specific conductivity and impressive lithium–ion diffusion rate, which makes the Cu2−xSe a promising anode material for lithium–ion batteries.

Sulfur, as a cathode material in lithium−sulfur batteries, has a very high theoretical specific capacity of 1675 mAh g−1, but there is still a large challenge, because of polysulfides’ (PSs) that cause a severe shuttle effect. To suppress this effect, a simple way of modifying separator by introducing lithium fluoride (LiF) as a coating layer was developed. Owing to the interaction between LiF and dimethoxymethane (DME, an electrolyte solvent), a dense and viscous sol layer was formed that suppresses PSs passing from the cathode to the anode. The presence of this layer was confirmed by using Fourier transform infrared spectroscopy, thermogravimetric/differential thermogravimetric, and scanning electron microscopy. The linear sweep voltammetry test had shown that the LiF-coated separator had a wide electrochemical window above 5 V vs. Li/Li+, and the cell assembled with the LiF-coated separator exhibited an excellent cycling performance with a capacity retention rate of 69.3%. Even without LiNO3 as an electrolyte additive, a high coulombic efficiency of 93% after 200 cycles at 0.2 C was achieved.

Lithium-sulfur battery has received extensive attention because of its high energy density, but its practical application has been limited by several problems such as short cycle life and low efficiency. In this study, we prepare monodispersed sulfur nanoparticles (S NPs) on partially reduced graphene oxide (S-prGO) during reduction of graphene oxide by spray method. The S-prGO composite is then recombined with polydopamine (PDA) to get the S-prGO-PDA composite. The S-prGO-PDA composite exhibits great cycling stability, coulombic efficiency and capacity retention. When charge-discharge at current density of 200 mA g−1, the specific capacity is 1122 mAh g−1 at the first discharge and 647 mAh g−1 after 100 cycles, with stable coulombic efficiency of 98%.

TiO2 hybrid nano composites are encouraging electrode materials for lithium-ion batteries due to the increased specific capacity and excellent electrochemical performance. In this work, the TiO2–MoS2 hybrid binder free electrodes have been successfully synthesized by using a facile hydrothermal process. Encouragingly, when being assessed as an anode electrode for LIBs, the MoS2–TiO2 electrode after the calcination treatment could retain a capacity of 361.5 mAh g−1 with high capacity retention of 88.0% after 300 cycles at a high current density of 800 mA g−1. Such good performance may be derived from the special 3D network architecture, well-dispersed MoS2 nanoparticles and the close connection between TiO2 and MoS2 after the calcination treatment.

ZnFe 2 O 4 and CoFe 2 O 4 materials are successfully prepared via solution combustion synthesis with glycine as fuel and complexing agent. The final products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The average diameter of the prepared particles is in the range of 80–100 nm. Cyclic voltammetry (CV), galvanostatic cycling and electrochemical impedance spectroscopy (EIS) studies are used to investigate the electrochemical properties of the MFe 2 O 4 (M = Zn, Co) particles. The reversible capacities of ZnFe 2 O 4 and CoFe 2 O 4 are 1037.2 mAh g −1 and 994.3 mAh g −1 , respectively, after 80 cycles at a current density of 200 mA g −1 . The capacity retentions are up to 104.2% and 106.6% compared to the second cycle. The as-synthesized samples also exhibit outstanding rate capability and long cycle life. After 300 cycles at a high current density of 1000 mA g −1 , the capacity retention are 109.3% and 87.4% compared to the second cycle with almost no capacity fading but increasing. It could still maintain reversible capacities of 794.7 mAh g −1 and 746.5 mAh g −1 , respectively. The superior electrochemical performance can be attributed to the macroporous structure in pure phase without any impurities, which can not only ease the volume expansion during the charge/discharge processes but also provide more interstices for lithium ions insertion. What is more, the high crystallinity of two samples is able to stabilize the microstructure no collapse after plenty of lithiation-delithiation processes. The results suggest that this method is a facile, effective and general way to synthesize excellent electrochemical properties of macroporous structure spinel Fe-based binary transition metal oxides as anode material for lithium ion batteries.

Micro/nanostructured Co 9 S 8 cubes and spheres (S-Co 9 S 8 ) were successfully prepared with Co 3 O 4 as templates via the vapor-based anion exchange reaction. The morphology and structure of both materials were characterized by SEM and XRD. Co 9 S 8 microcubes and microspheres were composed of nanoparticles, inheriting the micro/nanostructure of Co 3 O 4 precursors. Tested in lithium ion batteries, C-Co 9 S 8 and S-Co 9 S 8 anodes exhibited high specific capacities, excellent cycle stability (C-Co 9 S 8 : 369 mAh g −1 , S-Co 9 S 8 : 370 mAh g −1 over 300 cycles at 1C) and high rate performances (C-Co 9 S 8 : 450 mAh g −1 , S-Co 9 S 8 : ∼430 mAh g −1 at 5C).

Aluminum-ion batteries (AIBs) are supposed to be one of the energy storage systems with great potentialities on account of their high safety, low cost and high theoretical volumetric capacity. Herein, we report a novel rod-shaped Cu1.81Te cathode material for AIBs. At 40 mA g-1, the initial discharge capacity can reach 144 mA h g-1. The diffusion coefficient of Al3+ calculated by the galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) tests at different scan rates is larger than that in sulfides, indicating that telluride has faster kinetics. The results of ex situ X-ray photoelectron spectroscopy (XPS), ex situ X-ray diffraction (XRD) and 27Al nuclear magnetic resonance (NMR) prove that the mechanism of the charging and discharging processes is the reversible intercalation and deintercalation of Al3+, which is very important for the subsequent researchers to understand and investigate the mechanism of the Al/Cu1.81Te battery. This work also proves that telluride can also be used as a cathode material for aluminum storage.

Lithium-metal batteries have attracted extensive attention due to the increasing demand for storage devices with high energy density. For the modification of lithium-metal battery, how to effectively inhibit the growth of lithium dendrites has become a key challenge. Ether electrolytes have been widely used owing to their good compatibility with lithium metal. However, they are still difficult to be applied in high-voltage battery systems because of the poor cathodic stability. In this work, we have dissolved the lithium carboxylate, LiCO

Developing advanced high-rate electrode materials has been a crucial aspect for next-generation lithium ion batteries (LIBs). A conventional nanoarchitecturing strategy is suggested to improve the rate performance of materials but inevitably brings about compromise in volumetric energy density, cost, safety, and so on. Here, micro-size Nb

Graphite and non-graphitising (“hard”) carbons are important anode materials for battery technologies. The electrochemical intercalation of alkali metals in graphite has been widely studied by first-principles density-functional theory (DFT). However, similar investigations of disordered “hard” and nanoporous carbons have been challenging due to the structural complexity involved. Here, we combine DFT with machine-learning (ML) methods to study the intercalation of alkali metal (Li, Na, K) atoms in model carbon systems over a range of densities and degrees of disorder. We use a stochastic approach to compute voltage–filling profiles, studying the three metal species side-by-side, and we analyse the ionic charges of metal atoms as a function of filling. Our study provides atomic-scale insight into the intercalation of all three alkali metals that are relevant to batteries, and it thereby makes a key step towards the DFT/ML-driven modelling of energy materials.

In lithium-ion batteries (LIBs), benefiting from various functional components, functional separators can possess different capabilities to cope with the risks in complex application scenarios. In this work, a functional separator based on the phosphonate-modified nano-scale silica ceramic particles is fabricated to reduce the safety risks in LIBs. Through an anhydrous polymerization process, dimethyl vinylphosphonate (DMVP), a kind of widely used flame retardants, is grafted on silica (SiO2). Then the modified SiO2 (mSiO2) is coated on the pristine polyethylene separator by a typical coating process. Combining the function of the ceramic and phosphonate, the modified ceramic separator displays substantially enhanced thermal stability, without visual thermal shrink up to 200 °C. The flame resistances of separator itself and pouch cells are also significantly improved, even though flammable electrolyte is added. Different from the case when the phosphonate is used as an additive in electrolyte, the phosphonate is fixed firmly on the separator and not easy to be embedded in carbon anode after battery cycles. The coin cells assembled with the modified separators are away from the irreversible loss of discharge capacity and low Coulombic efficiency for the first cycle, which can be attributed to the firm immobilization of organic phosphonate.

The energy density of LiNi0.5Co0.2Mn0.3O2 (NCM523) can be enhanced by increasing the upper-limit charging potential, but it exhibits a significant “capacity decay” during cycling. Therefore, it is necessary to study the intrinsic mechanism for the performance improvement of high-voltage NCM523. In this work, through combining the intrinsic state-of-charge (SOC) of NCM523 revealed by Raman spectroscopy with the electrochemical characterization, the kinetic degradation of Li+ de-/intercalation is found to be a key factor for the apparent capacity decay of NCM523 under the high upper-limit charging potential (>4.3 V). Meanwhile, the apparent capacity loss can be restored significantly by reducing the current density or increasing the operating temperature. Furthermore, the formation of the electrochemical passivation layer on the surface of NCM523 particles is detected by the surface characterization of high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), which is proved to be another important factor for the kinetic degradation, besides the particle pulverization of NCM523 and the decomposition products of electrolyte adsorbed on the material surface. Thus, this work can help to rationally improve the electrochemical performance of the high-voltage NCM523.

It has been a challenge to accurately simulate Li-ion diffusion processes in battery materials at room temperature using {\it ab initio} molecular dynamics (AIMD) due to its high computational cost. This situation has changed drastically in recent years due to the advances in machine learning-based interatomic potentials. Here we implement the Deep Potential Generator scheme to \textit{automatically} generate interatomic potentials for LiGePS-type solid-state electrolyte materials. This increases our ability to simulate such materials by several orders of magnitude without sacrificing {\it ab initio} accuracy. Important technical aspects like the statistical error and size effects are carefully investigated. We further establish a reliable protocol for accurate computation of Li-ion diffusion processes at experimental conditions, by investigating important technical aspects like the statistical error and size effects. Such a protocol and the automated workflow allow us to screen materials for their relevant properties with much-improved efficiency. By using the protocol and automated workflow developed here, we obtain the diffusivity data and activation energies of Li-ion diffusion that agree well with the experiment. Our work paves the way for future investigation of Li-ion diffusion mechanisms and optimization of Li-ion conductivity of solid-state electrolyte materials.

The fuel cells have outstanding advantages in the new energy application, but the membrane electrode assembly (MEA) of fuel cells is difficult to produce at low-cost and large-scale, which restricts their applications. To simplify the preparation of MEA, for the first time, we successfully develop a novel impregnation-reduction method combined with galvanic replacement to grow Ag/Pt bimetallic nanocatalyst onto a Nafion membrane (Nafion-Ag/Pt membrane), and the deposited Ag/Pt catalyst is very stable, which can be directly used as a novel ultra-thin catalyst layer in MEA. This novel method possesses mild conditions, simple procedure, good repeatability and practicability in a large-scale production. Moreover, a very low Pt loading amount of Nafion-Ag/Pt membrane can be achieved by regulating experimental conditions, which brings excellent Pt utilization. Therefore, the MEA made from Nafion-Ag/Pt membrane exhibits a Pt mass specific power (1.519 W mgPt −1) that is 12.3 times higher than that of a conventional MEA. These results demonstrate that this novel impregnation-reduction method can reduce the cost of fuel cells by reducing the difficulty of MEA preparation and the Pt loading amount of MEA and simultaneously enhancing its performance, which shows great potential in fuel cell application.

TiO2 nanoparticles with oxygen vacancies (B-P25) prepared by NaBH4 reduction method were coated onto PE separator to construct an active ceramic layer. The effect of the functional layer was carefully studied especially the interaction between oxygen vacancies on B-P25 and species in the liquid electrolyte. The B-P25 not only improves the affinity between the separator and electrolyte, but also improves the lithium ion transference number of the electrolyte, from 0.28 to 0.50. Based on the infrared spectroscopy results, it was found that B-P25 weakened the coordination between Li+ and EC, and partially desolvated the Li+-EC complex. Further theoretical calculation showed that the oxygen vacancies are more likely to adsorb EC molecules and indirectly promote the dissociation of Li+-EC, so that partially solvated Li+ has a stronger mobility and a higher lithium ion conductivity in the electrolyte. Therefore, B-P25 as an active layer assembled in LiFePO4 half-cell has better rate performance.

To optimize the electrochemical behavior of NCM-based high-energy lithium-ion batteries (LIBs) in wide temperature ranges, Phenyl trifluoromethane sulfonate (PTM) is demonstrated as the novel electrolyte additive to enhance the electrochemical behavior of LiNi0·6Co0·2Mn0·2O2/graphite cells at 25 °C, −20 °C and 45 °C. The cells with 1.0 wt% PTM-containing electrolyte deliver 80.6% capacity retention after 350 cycles at 25 °C, 73.4% after 100 cycles at −20 °C, and 82.6% after 300 cycles at 45 °C, which are significantly higher than that in standard electrolyte (STD), corresponding to 36.4% at 25 °C, 40.3% at −20 °C, and failure at 45 °C, respectively. According to density functional theory (DFT) simulations and quantitative calculations, the PTM preferentially reduces on the anode and oxidizes on the cathode to participate in the formation of solid electrolyte interphase (SEI) films. In addition, the scanning electron microscopy (SEM), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and other analysis suggest that the formed SEI films are thinner and more stable for the electrolyte containing PTM, and the formed SEI films effectively control the decomposition of carbonate-based electrolytes and greatly decrease the increased resistance during the cycle.

Aqueous rechargeable Zn metal batteries have attracted widespread attention due to the intrinsic high volumetric capacity, low cost, and high safety. However, the low Coulombic efficiency and limited lifespan of Zn metal anodes resulting from uncontrollable growth of Zn dendrites impede their practical application. In this work, a 3D interconnected ZnF2 matrix is designed on the surface of Zn foil (Zn@ZnF2 ) through a simple and fast anodic growth method, serving as a multifunctional protective layer. The as-fabricated Zn@ZnF2 electrode can not only redistribute the Zn2+ ion flux, but also reduce the desolvation active energy significantly, leading to stable and facile Zn deposition kinetics. The results reveal that the Zn@ZnF2 electrode can effectively inhibit dendrites growth, restrain the hydrogen evolution reactions, and endow excellent plating/stripping reversibility. Accordingly, the Zn@ZnF2 electrode exhibits a long cycle life of over 800 h at 1 mA cm-2 with a capacity of 1.0 mAh cm-2 in a symmetrical cell test, the feasibility of which is also convincing in Zn@ZnF2 //MnO2 and Zn@ZnF2 //V2 O5 full batteries. Importantly, a hybrid zinc-ion capacitor of the Zn@ZnF2 //AC can work at an ultrahigh current density of ≈60 mA cm-2 for up to 5000 cycles with a high capacity retention of 92.8%.

A binder-free nest-like structured MnOx@carbon nanotubes anode for lithium-ion batteries (LIBs) was prepared through a facile electrophoretic deposition (EPD) method. Through the EPD process, both MnO2 nanowires and carbon nanotubes (CNTs), as starting materials, were interwoven tightly to form a uniform co-deposited film, possessing a nest-like architecture. After annealing the film under an inert atmosphere, the MnO2 nanowires transformed into Mn3O4 and MnO, as confirmed by the X-ray diffraction patterns. The nest-like electrode formed a porous and integrated conductive framework and provided the buffer space for the volume change of manganese oxides during cycling processes. As a result, this MnOx@CNTs electrode exhibited excellent cycling performance with a reversible capacity of 1152.1 mAh g−1 at 0.2 A g−1 and a superior cycling stability with 88.0 % capacity retention at 1 A g−1 after 200 cycles.

We report an effective double current collector electrode. In this study, we achieve a high areal loading double current collector electrode with high areal capacity density and long cycle life. We also adjust the charging condition (constant capacity charging) which leads to long cycle life with almost no capacity fading.

Composite membranes have been fabricated made of ultrafine PVDF fibers via a tip-induced electrospinning (TIE) process and Al2O3 nanoparticles via a dip-coating process. These membranes exhibit good thermal stability and electrochemical properties as the separators for applications in lithium ion batteries (LIBs). Experimental results show that the as-fabricated separators may mechanically contract less than 2% when kept at a high temperature of 140 °C for an hour showing good thermal stability as compared with commercial polypropylene separators and electrospun PVDF membranes. The membrane has a measured porosity of 55.8% and ionic conductivity of 2.23 mS cm−1, achieving a low battery discharge capacity loss of 1.8% after 100 cycles in the 1.0C-rate tests, and a retention rate of 92.9% in the 4C-rate tests. These results show the great potential of PVDF/Al2O3 separators in LIB applications under high temperature and high current/power operations.

In this work, CuS/graphene (CuS-G) composite is synthesized via one-pot microwave irradiation method under ambient conditions. As anode material for lithium ion batteries, the CuS-G composite delivers a significantly enhanced reversible capacity and charge/discharge cycle stability compared with pristine CuS. A capacity of 348 mAh g−1 can be maintained after 1000 cycles at the current density of 2.0 A g−1. Electrochemical impedance spectroscopy (EIS) along with cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) measurements indicate that the incorporation of graphene sheets reduces the contact resistance and enhances lithium ion transfer rate during the electrochemical lithium insertion/extraction remarkably. Thus, as-prepared CuS spheres can be a promising anode material for high performance lithium ion batteries.

Wastewater sludge from metropolitan areas has become a source of polycyclic aromatic hydrocarbons (PAHs), and may result in pollution of soils and plants if applied to agricultural areas. It is important to stabilize wastewater sludge before its application to agricultural land. Constructed wetlands (CWs) have been widely applied for stabilization of sludge. In CWs, plants, especially reeds, promote degradation of pollutants in the rhizosphere and are the principal mechanisms for PAH-contaminated sludge phytoremediation. We studied PAH removal in sludge planted with Phragmites australis (common reeds) in onsite experiments over a 3-year period comprising 2 years of sludge application and 1 year of resting. The average PAH content in the feeder sludge was 5.7 mg kg–1 (DW), consisting of approximately 48% low-molecular-weight (2–3 ring) PAHs, 27% middle-molecular-weight (4 ring) PAHs and 25% high-molecular-weight (5–6 ring) PAHs. After 3 years, the average PAH content in stabilized sludge was 2.1 mg kg–1 (DW), which was lower than that of the feeder sludge. Overall, about 66% of low-molecular-weight PAHs (dominant type), 57% of middle-molecular-weight PAHs and 32% of high-molecular-weight PAHs were removed from the stabilized sludge. Additionally, there were spatial variations in PAHs in stabilized sludge, with PAHs being highest in the surface layer (12–14 cm) sludge, lower in the middle layer (6–8 cm) and lowest in the bottom layer (0–2 cm).

Silicon-multi-walled carbon nanotubes-carbon (Si-MWNTS-C) microspheres have been fabricated through the ball milling and spray drying method followed by the carbonization process. The as-prepared composite microspheres are confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The specific capacity of the as-prepared microspherical composite as anode in lithium-ion batteries (LIBs) is about 1100 mAh g−1 at the current density of 0.2 A g−1 (based on the total weight of the composite). At the high current density of 6 A g−1, the Si-MWNTS-C microspheres exhibit reversible capacity of 415 mAh g−1. Through the ex situ SEM, we observed that the Si-MWNTS-C microspherical composite particles have no extinct change on the electrode surface except for the growth of the spherical particles after 100 cycles. The excellent electrochemical performance is ascribed to the synergistic effect between Si nanoparticles (Si NPs) and MWNTS-C microspheres. The as-prepared Si-MWNTS-C microspheres can effectively accommodate large volume changes and provide a 3D conductive network during the lithiation–delithiation processes.