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In this study, CO₂ conversion to acetate and CH₄ was achieved in a flow-through laboratory-scale microbial electrosynthesis (MES) cell composed of a 3D conductive polylactic acid (cPLA) lattice cathode with electrodeposited metal electrocatalyst coatings. The MES cell with a bare cPLA cathode showed the poorest performance with the lowest H₂ and CH₄ production rates and low Coulombic efficiency. This was ascribed to a poor electrocatalytic activity of cPLA towards H₂ production and high electrode resistivity. When the cPLA electrode was modified with metal coatings, the CH₄, acetate and H₂ production rate increased significantly, with the following trend: cPLA < Ni < NiFe < NiFeMn. The better performance of the metal-coated cPLA in terms of CH₄ production was attributed to the lower electrical resistance, enhanced H₂ production and enhanced electron transfer between the cathode and the biofilm. At the cell potential of 2.8 V, the best-performing NiFeMn cPLA cathode showed stable production of CH₄ (50 ± 6 mL d⁻¹), acetate (185 ± 27 mg d⁻¹), and H₂ (545 ± 175 mL d⁻¹) at close to 100% Coulombic efficiency.

Aqueous zinc-air battery (ZAB) has attractive features as the potential energy storage system such as high safety, low cost and good environmental compatibility. However, the issue of dendrite growth on zinc metal anodes has seriously hindered the development of ZAB. Herein, the N-doped carbon cloth (NC) prepared via magnetron sputtering is explored as the substrate to induce the uniform nucleation of zinc metal and suppress dendrite growth. Results show that the introduction of heteroatoms accelerates the migration and deposition kinetics of Zn2+ by boosting the desolvation process of Zn2+, eventually reducing the nucleation overpotential. Besides, theoretical calculation results confirm the zincophilicity of N-containing functional group (such as pyridine N and pyrrole N), which can guide the nucleation and growth of zinc uniformly on the electrode surface by both promoting the redistribution of Zn2+ in the vicinity of the surface and enhancing its interaction with zinc atoms. As a result, the half-cell assembled with magnetron sputtered carbon cloth achieves a high zinc stripping/plating coulombic efficiency of 98.8% and long-term stability of over 500 cycles at 0.2 mA cm-2. And the Coulombic efficiency reached about 99.5% at the 10th cycle and maintained for more than 210 cycles at a high current density of 5.0 mA cm-2. The assembled symmetrical battery can deliver 220 plating/stripping cycles with ultra-low voltage hysteresis of only 11 mV. In addition, the assembled zinc-air full battery with NC-Zn anode delivers a high special capacity of about 429 mAh gZn-1 and a long life of over 430 cycles. The effectiveness of surface functionalization in promoting the transfer and deposition kinetics of Zn2+ presented in this work shows enlightening significance in the development of metal anodes in aqueous electrolytes.

To explore the natural resources as sustainable precursors offers a family of green materials. The use of bio-waste precursors especially the remaining from food processing is a scalable, highly abundant, and cost-effective strategy. Exploring waste materials is highly important especially for new materials discovery in emerging energy storage technologies such as lithium sulfur batteries (LSBs). Herein, waste milk powder is carbonized and constructed as the sulfur host with the hollow micro-/mesoporous framework, and the resulting carbonized milk powder and sulfur (CMP/S) composites are employed as cathodes for LSBs. It is revealed that the hollow micro-/mesoporous CMP/S framework can not only accommodate the volume expansion but also endow smooth pathways for the fast diffusion of electrons and Li-ions, leading to both high capacity and long cycling stability. The CMP/S composite electrode with 56 wt.% loaded sulfur exhibits a remarkable initial capacity of 1596 mAh g−1 at 0.1 C, corresponding to 95% of the theoretical capacity. Even at a rate of 1 C, it maintains a high capacity of 730 mAh g−1 with a capacity retention of 72.6% after 500 cycles, demonstrating a very low capacity fading of only 0.05% per cycle. Importantly, the Coulombic efficiency is always higher than 96% during all the cycles. The only used source material is expired waste milk powders in our proposal. We believe that this “trash to treasure” approach will open up a new way for the utilization of waste material as environmentally safe and high performance electrodes for advanced LSBs.

The CuO/CeO2 composites with strong metal-support interaction were synthesised, which can efficiently electroreduct CO2 to C2H4. The Faradaic efficiency (FE) of C2H4 could reach 50.5% with a current density of 18 mA cm−2. The strong metal-support interaction could not only enhance the adsorption and activation of CO2, but also can stablize the CuO.

Tuning surface electron transfer process by sulfur (S)-vacancies engineering is an efficient strategy to develop high-efficient catalysts for electroreduction N2 reaction (NRR). Herein, the distinct Sb2S3 nanorods with S-vacancies (Sv-Sb2S3) have been synthesized by a simple two-step method including hydrothermal and hydrogenation in H2/Ar atmosphere, which shows improved performance for NRR with the NH3 yield rate of 10.85 μg h−1 mgcat−1 at −0.4 V vs. RHE, the faradaic efficiency (FE) of 3.75% at −0.3 V vs. RHE and excellent stability for 24 h, largely outperforming bulk Sb2S3. X-ray photoelectron spectroscopy (XPS) and density function theory (DFT) calculations demonstrate that the abundant S-vacancies can create an electron-deficient environment and modulate the electron delocalization in Sv-Sb2S3, which can not only facilitate the N2 molecule adsorption, but also activate the N[tbnd]N, resulting in the enhanced performance for NRR. © 2020 Institute of Process Engineering, Chinese Academy of Sciences

Aqueous zinc energy storage devices, holding various merits such as high specific capacity and low costs, have attracted extensive attention in recent years. Nevertheless, Zn metal anodes still suffer from a short lifespan and low Coulombic efficiency due to corrosion and side reactions in aqueous electrolytes. In this paper, we construct an artificial Sn inorganic layer on Zn metal anode through a facile strategy of atoms exchange. The Sn layer suppresses Zn dendrite growth by facilitating homogeneous Zn plating and stripping during charge and discharge processes. Meanwhile, the Sn protective layer also serves as a physical barrier to decrease Zn corrosion and hydrogen generation. As a result, The Sn-coated anode (Sn|Zn) exhibits a low polarization voltage (∼34 mV at 0.5 mAh/cm2) after 800 testing hours and displays a smooth and an even surface without corrosion. Moreover, the zinc ion capacitor (Sn|Zn|| activated carbon) is assembled with an enhanced capacity of 42 mAh/g and a capacity retention of 95% after 10000 cycles at 5 A/g. This work demonstrates a feasible approach for the commercialization of aqueous Zn-based energy storage devices.

Inspired by the relatively recognized performance of transition metal sulfides in the oxidation of hydrazine, the catalytic properties of FeS2 and Fe3S4 are compared via the density functional theory calculations. Due to the different coordination numbers of iron-sulfur, the free energies of the dehydrogenation steps on FeS2 are far less than those on Fe3S4, which led to the much better catalytic performance of FeS2. Accordingly, FeS2 microspheres are rationally proposed as a more efficient electrocatalyst for hydrazine oxidation, which is then prepared by a facile one-step hydrothermal strategy. Such FeS2 microspheres show great activity for hydrazine oxidation with an onset oxidation potential of 0.22 V vs. reversible hydrogen electrode, and a peak current density of 16 mA cm−2. Meanwhile, stability and high faradaic efficiency (3.5e−/N2H4) is obtained for hydrazine oxidation to N2.

The sluggish kinetics for water oxidation is recognized as one of the major problems for the unsatisfied photoelectrochemical (PEC) performance. Herein, we developed a feasible strategy based on in-situ selective surface cation exchange, for activating surface water oxidation reactivity toward boosted PEC water oxidation of BiVO4 photoanodes with fundamentally improved surface charge transfer. The as-constructed Co/BiVO4 photoanodes exhibit 2.6 times increase in photocurrent density with superior stability, in comparison to those of pristine counterpart. Moreover, the faradaic efficiency of as-fabricated photoanode can be up to ∼95% at 1.23 V (vs. RHE). The unique selective replacement of Bi by Co on the surface could modify the electronic structure of BiVO4 with reduced energy barrier of the deprotonation of OH* to O, thus favoring the overall excellent PEC performance of Co/BiVO4 photoanode.

The increase of atmospheric CO2 concentration has caused many environmental issues. Electrochemical CO2 reduction reaction (CO2RR) has been considered as a promising strategy to mitigate these challenges. The electrocatalysts with a low overpotential, high Faradaic efficiency, and excellent selectivity are of great significance for the CO2RR. Carbon-based materials including metal-free carbon catalysts and metal-based carbon catalysts have shown great potential in the CO2RR, owing to the tailorable porous structures, abundant natural resources, resistance to acids and bases, high-temperature stability, and environmental friendliness. In this review, various carbon materials including graphene, carbon nanotubes, quantum dots, porous carbon, and MOF-derived catalysts, etc., for the CO2RR have been summarized. Particularly, recent progress in terms of the mechanism and pathway of CO2 conversion has been comprehensively reviewed. Finally, the opportunities and challenges of carbon-based electrocatalysts for the CO2RR are proposed.

It is urgent to develop highly efficient, stable and low-cost bifunctional electrocatalysts for overall water splitting. Herein, an iron-nickel phosphide (Fe2P/Ni2P) heterostructure, constructed by Fe2P nanoparticles embedded on Ni2P nanosheets, is strategically fabricated on nickel foam via a facile process. As a bifunctional electrocatalyst, the Fe2P/Ni2P heterostructure delivers a very low overpotential of 64 mV (or 185 mV) to reach current density of 10 mA cm−2 for hydrogen (or oxygen) evolution reaction. When simultaneously employed as both the anode and cathode electrodes, it demonstrates an ultralow cell voltage of 1.49 V@10 mA cm−2 for full water splitting with nearly 100% Faradaic efficiency, and superior long-term stability even over 100 h. Density functional theory calculations manifest that a strong heterointerface interaction could cause electron redistribution near the Fe2P/Ni2P heterointerface and optimize the ΔGH* of P sites, thus enhancing catalytic activity. Additionally, the 3D porous heterostructure is benefit to expose rich active sites and facilitate ion diffusion and gas bubble release, thus promoting the catalytic performance. This work opens up a new strategical approach for rational design of metal phosphide-based heterostructures as highly efficient and stable bifunctional electrocatalysts for water splitting.

The exertion of superior high-energy density based on multivalent ions transfer of rechargeable aluminum batteries is greatly hindered by limited electrochemical stability window of typical water in salt electrolyte (WiSE). Recently, it is reported that a second salt addition to the WiSE can offer further suppression of water activities, and achieves a much wider electrochemical window compared with aqueous WiSE electrolytes. Hence, we demonstrate a class of water in bi-salt electrolyte containing the trifluoromethanesulfonate (OTF), which exhibits an ultra-wide electrochemical window of 4.35 V and a very low overpotential of 14.6 mV. Moreover, the interface chemistry between cathode and electrolyte is also confirmed via kinetic analysis. Surprisingly, we find the electrolyte can effectively suppress Mn dissolution from the cathode, alleviate self-discharge behavior, and ensure a stable electrode–electrolyte interface based on the interface concentrated-confinement effect. Owing to these unique merits of water in bi-salt electrolyte, the AlxMnO2·nH2O material delivers a high capacity of 364 mAh g−1 and superb long-term cycling performance > 150 cycles with a capacity decay rate of 0.37% per cycle with coulombic efficiency at ca. 95%.

The electrocatalytic nitrogen reduction reaction (NRR) has emerged as a promising renewable energy source and a feasible strategy as an alternative to Haber-Bosch ammonia (NH3) synthesis. However, finding an efficient and cost-effective robust catalyst to activate and cleave the extremely strong triple bond in nitrogen (N2) for electrocatalytic NRR is still a challenge. Herein, a FeNi@CNS nanocomposite as an efficient catalyst for N2 fixation under ambient conditions is designed. This FeNi@CNS nanocomposite was prepared by a simple water bath process and post-calcination. The FeNi@CNS is demonstrated to be a highly efficient NRR catalyst, which exhibits better NRR performance with exceptional Faradaic efficiency of 9.83% and an NH3 yield of 16.52 μg h − 1 cm−2 in 0.1 M Na2SO4 aqueous solution. Besides, high stability and reproducibility with consecutive 6 cycles for two hours are also demonstrated throughout the NRR electrocatalytic process for 12 h. Meanwhile, the FeNi@CNS catalyst encourages N2 adsorption and activation as well as effectively suppressing competitive HER. Therefore, this earth-abundant FeNi@CNS catalyst with a subtle balance of activity and stability has excellent potential in NRR industrial applications.

Electrochemical nitrogen reduction reaction (NRR) has been identified as a prospective alternative for sustainable ammonia production. Developing cost-effective and highly efficient electrocatalysts is critical for NRR under ambient conditions. Herein, the hierarchical cobalt-molybdenum bimetallic sulfide (CoS2/MoS2) flower-like heterostructure assembled from well-aligned nanosheets has been easily fabricated through a one-step strategy. The efficient synergy between different components and the formation of heterostructure in CoS2/MoS2 nanosheets with abundant active sites makes the non-noble metal catalyst CoS2/MoS2 highly effective in NRR, with a high NH3 yield rate (38.61 μg h–1 mgcat.–1), Faradaic efficiency (34.66%), high selectivity (no formation of hydrazine) and excellent long-term stability in 1.0 mol L–1 K2SO4 electrolyte (pH=3.5) at − 0.25 V versus the reversible hydrogen electrode (vs. RHE) under ambient conditions, exceeding much recently reported cobalt- and molybdenum--based materials, even catch up with some noble-metal-based catalyst. Density functional theory (DFT) calculation indicates that the formation of N2H* species on CoS2(200)/MoS2(002) is the rate-determining step via both the alternating and distal pathways with the maximum ΔG values (1.35 eV). These results open up opportunities for the development of efficient non-precious bimetal-based catalysts for NRR.

Electrochemical CO2 reduction (ECR) powered by renewable energy sources provides a sustainable avenue to producing carbon-neutral fuels and chemicals. The design and development of high performance, cost-effective, and stable catalysts for ECR remain a focus of intense research. Here, we report a novel electrocatalyst, two-dimensional cadmium-based 1,4-benzenedicarboxylate metal-organic frameworks (Cd-BDC MOFs) which can effectively convert CO2 to CO with a faradaic efficiency (FE) of more than 80.0% over the voltage range between −0.9 and −1.1 V (versus reversible hydrogen electrode, vs. RHE) in 0.1 mol·L−1 CO2-saturated KHCO3 solution with an H-type cell, reaching up to 88.9% at −1.0 V (vs. RHE). The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature. The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type. Especially, high CO FEs exceeding 90.0% can be attained on the Cd-BDC electrode at potentials ranging from −0.16 to −1.06 V (vs. RHE) in 0.5 mol·L−1 KHCO3 solution by using a gas diffusion electrode cell system. The maximum CO FE approaches ∼97.6% at −0.26 V (vs. RHE) and the CO partial geometric current density is as high as about 108.1 mA cm–2 at −1.1 V (vs. RHE). This work offers an efficient, low cost, and alternative electrocatalyst for CO2 transformation.

Anode-free batteries (AFBs) have the potential of ultra-high energy density, but lithium dendrite has largely hindered their practical applications. In this work, an in-situ grown gradient solid electrolyte interface (SEI) layer on pre-designed micro-hole-grid (MHG) Cu reservoir is proposed to guide uniform lithium deposition and propagation, by which the electrode interface is stabilized and the surface stress is considerably decreased endowing the AFBs with outstanding areal capacity and cycling performance. The gradient SEI is confirmed by cryogenic-transmission electron microscopy (Cryo-TEM) and XPS to be composed of (1) an elastic organic top layer to hinder non-Li species migration and withstand volume fluctuation, and (2) a lithophilic LiCl-rich bottom layer to render the rapid lithium supply. Operando electron paramagnetic resonance (EPR) shows a dynamic Li deposition, unambiguously demonstrating a dendrites-free behavior. As a result, the full cells of a gradient SEI modified Cu reservoir paired with a LiFePO4 cathode exhibit high capacity of 95 mAh g–1 and Coulombic efficiency (CE) of 99.5% after 100 cycles, much better than the control cells with planar current collectors (1.6 mAh g–1, 2.6%). These findings are enlightening in engineering better interphases for high energy and safe rechargeable lithium metal batteries.

Implementation of sodium metal anode is highly desired for sodium batteries due to its high theoretical capacity and low redox potential. Unfortunately, formation of unstable solid electrolyte interphase (SEI) and uncontrollable growth of dendrites during charge/discharge cycles greatly hinder the practical application of sodium metal anode. In this study, an organic-metal artificial layer made of PVdF and Bi was constructed to protect Cu current collector via a facile coating method, leading to smooth and dense sodium plating/stripping, which in retern enables stable cycling and high coulombic efficiency (CE). At 1 mA cm−2, PB@Cu current collector presents extended lifetime of ~2500 h with high sodium utilization of 50%, which is approximately six times higher than Cu current collector. PB@Cu electrode also displays high average CE of 99.92% and 99.95% over 2500 and 1300 cycles at 1 and 2 mA cm−2 respectively, which is in sharp contrast to the low and tremendously fluctuant CE gained from bare Cu electrode. Moreover, stable capacity of > 90 mAh g−1 over 150 cycles is realized for PB@Cu-based full cell assembled with NVP cathode at a low negative-positive capacity ratio of ~3.5, which is significantly higher than 37.2 mAh g−1 obtained from NVP/Cu at 150th cycle. The superior electrochemical performance of PB@Cu current collector is revealed to originate from the alloyed Na3Bi phase with high sodium conductivity and robust mechanical strength as well as the formation of NaF-rich SEI with fast sodium ion migration, which enable dendrite-free morphology during plating/stripping cycles.

While membrane-free batteries have been successfully demonstrated in static batteries, membrane-free batteries in authentic flow modes with high energy capacity and high cyclability are rarely reported. Here, we present a biphasic flow battery with high capacity employing organic compound in organic phase and zinc in aqueous phase. Under ambient flow testing conditions, a capacity retention of 94.5% is obtained over 190 charging/discharging cycles with a Coulombic efficiency of > 99% at a current density of 8.54 mA cm−2. Self-discharge at full state-of-charge of the membrane-free RFB is negligible (potential drop = 0.78 mV h−1). DFT calculation and operando UV-visible and FT-IR spectroscopies are performed to probe minor side reactions during cycling and monitor the water content in the organic electrolyte in real time. The successful demonstration of the prototypical membrane-free battery under flow conditions, together with the developed operando spectroscopic techniques, will open a new avenue towards detailed mechanistic studies and practical applications of redox flow batteries for cost-effective energy storage.

CO2 electroreduction reaction (CO2RR), combined with solid oxide electrolysis cells (SOECs), is a feasible technology for the storage of renewable electric energy, while its development is limited by the catalytic activity and stability on cathodes. Here, a novel garnet oxide (Gd3Fe5O12) cathode is designed, where the garnet oxide is converted to perovskite oxide and iron via in situ electrochemical phase transition during CO2 electroreduction, resulting in high activity with Faradaic efficiency close to 100% and great stability over 1000 h galvanostatic test. A variety of experimental characterizations and density functional theory calculations indicate that in situ exsolved Fe clusters can effectively enhance the adsorption energies of intermediates and lowering the CO2 dissociation barriers. Microkinetic modelling confirms that CO2RR goes through a dissociative adsorption mechanism and the electronic transfer for CO2 dissociation is the rate-determining step.

Alkali (Li/Na/K) metal anodes (AMAs), because of their remarkably high energy density and low redox potential, are considered as the most promising anodes for next-generation high-energy battery systems. Nevertheless, high reactivity and uncontrollable volume change of metal anodes during plating/striping inevitably generate dendritic metal and unstable solid electrolyte interphase, inducing low Coulombic efficiency, inferior cycling stability and even safety issues. Architecture design is emerged as an effective approach to address these fatal issues and plenty of attempts have been conducted so far. Instead of simply summarizing the structure-designing strategies to modify AMAs, the review is dedicated to overviewing and categorizing the strategies of architecture design towards the challenges of AMAs by their fundamental design principles from the perspective of electrochemical reaction. Besides, the similarities and differences of three types of alkali metals, in terms of mechanical and chemical properties, have been systematically discussed. Finally, we overviewed the existing challenges, perspectives on further development direction, and outlook for practical applications for AMAs.

The chemical vulnerability of sulfide solid electrolyte (SE) materials to organic polar solvents complicates the wet-slurry fabrication of sheet-type electrodes and SE films for practical all-solid-state Li batteries (ASLBs). Moreover, the disruption of interfacial Li+ conduction by binders is problematic. This could be relieved by blending with liquid electrolytes but at the expense of the ASLBs’ thermal stability. In this study, a new tactical approach to hybridize sulfide SEs with thermally stable and slurry-fabricable dry polymer electrolyte (DPE)-type binders is reported. Along with their practicability, ester solvents bearing bulky hydrocarbons, such as benzyl acetate, dissolve both polymers and Li salts (e.g., LiTFSI) while undamaging sulfide SEs. The use of the DPE-type binder, NA-LiTFSI (NA: nitrile butadiene rubber-poly(1,4-butylene adipate)), for LiNi0.70Co0.15Mn0.15O2 (NCM) electrodes significantly improves their electrochemical performance at 30 °C. Moreover, NA-LiTFSI is highly functional at 70 °C (from 180 to 200 mA h g−1 and from 84.2 to 91.8% for initial Coulombic efficiency) and applicable for other electrodes, such as graphite (from 265 to 330 mA h g−1) and Li4Ti5O12, which is in stark contrast to the solvate ionic liquid-type binder Li(G3)TFSI. Finally, pouch-type NCM/graphite ASLBs employing electrodes made of NA-LiTFSI binders were also fabricated.

A novel negative material consisting of graphene nanotubes and ultrathin MoS2 is synthesized by a simple one-step hydrothermal method assisted with Sodium chloride. The MoS2/Graphene electrodes deliver a specific capacity of 1350 mAh g−1 under 0.1 A g−1 and high rate capability (retaining 85.5% capacity from 0.1 A g−1 to 0.8 A g−1). A high remarkable capacity of 820 mAh g−1 can still be recovered at 0.5 A g−1 after 500 cycles, and the average coulombic efficiency was as high as 99.98% during the additional 500 cycles. The excellent Li-ion storage performance of MoS2/Graphene nanotubes may be attributed to the ultra-thin MoS2 flakes and curled graphene nanotubes. This structural feature has a strong adsorption capacity for lithium ions, which can provide a broad space for ion storage. A large number of active sites dispersed in the layered molybdenum disulfide promote the kinetics of the electrochemical reaction, empowering the ultra-thin layered molybdenum disulfide to get a higher theoretical capacity. In addition, the existence of the tubular structure alleviates volume expansion and provides a way for the rapid movement of electrons and diffusion of Li+ during repeated cycles.

Silicon-based anode materials with high theoretical capacity have great challenges of enormous volume expansion and poor electronic conductivity. Herein, a novel dual carbon confined SiOx/C@void@Si/C yolk-shell monodisperse nanosphere with void space have been fabricated through hydrothermal reaction, carbonization, and in-situ low-temperature aluminothermic reduction. Furthermore, the O/Si ratio and void space between SiOx/C core and Si/C shell can be effectively tuned by the length of aluminothermic reduction time. The SiOx/C core plays a role of maintaining the spherical structure and the void space can accommodate the volume expansion of Si. Moreover, the inner and outer carbons not only alleviate volume variation of SiOx and Si but also enhance the electrical conductivity of composites. Benefiting from the synergy of the double carbon and void space, the optimized VSC-14 anode affords prominent cycle stability with reversible capacity of 1094 mAh g-1 after 550 cycles at 200 mA g-1. By pre-lithiation treatment, the VSC-14 achieves an initial Coulombic efficiency of 93.27% at 200 mA g-1 and a reversible capacity of 348 mAh g-1 at 5 A g-1 after 4000 cycles. Furthermore, the pouch cell using VSC-14 anode and LiFePO4 cathode delivers a reversible capacity of 138 mAh g-1 at 0.2 C. We hope this strategy can provide a scientific method to synthesis yolk-shell Si-based materials.

Room-temperature Na-ion batteries have attracted great interest for over a decade owing to their natural abundance and similar intercalation chemistry with Li-ion. However, due to the uncontrolled decomposition of electrolyte and formation of solid electrolyte interphase, the large majority of sodium anode materials exhibit extremely low initial Coulombic efficiency and unsatisfactory cycling stability. Here we introduce a novel layered material, P2-Na0.547[Mg0.25Mn0.75]O2, as an SEI-free negative electrode. This material, delivers a reversible capacity of 126 mAh g−1 with a high initial Coulombic efficiency of 108%, and capacity retention of ∼ 80% after 1000 cycles at 4C rate. Pairing with Na3V2(PO4)3 cathode, excellent rate performance of ∼ 60% capability at 15C, and extra-high initial Coulombic efficiency of 97% are achieved, all attributed to the SEI-free feature of Na0.547[Mg0.25Mn0.75]O2. These results demonstrate the practical potential of our SEI-free anode material for high-power and long-life Na-ion batteries.

All-solid-state lithium batteries (ASSLBs) employ high-capacity lithium (Li) metal as the anode and exhibit a higher energy density than that of conventional Li-ion batteries. However, the problems arose from the Li dendrites induce severely parasitic reaction between Li and electrolytes, leading to low coulombic efficiency (CE) and poor cyclic stability. Herein, a poly(vinylidene-co-hexafluoropropylene)/lithium nitrate (PVDF-HFP/LiNO3, marked as PFH/LN) artificial layer is employed to modified Li and achieve high CE ASSLBs with polyethylene oxide-Li6.4La3Zr1.4Ta0.6O12 (PEO-LLZTO) electrolyte. LN serves as a functionalized additive to facilitate the formation of a robust solid electrolyte interface (SEI), efficiently suppressing the formation of Li dendrites. Additionally, LN as a “binder” effectively links PFH with Li, providing good contact. PFH possesses high mechanical strength and moderate flexibility, which can not only physically inhibit the growth of Li dendrites, but also maintain the structural integrity of artificial layer over long-term cycles. Finally, Li/Li cells with such artificial layer demonstrate ultralong cycle life of 1800 and 1000 h under 0.2 and 0.4 mA cm–1, respectively. Furtherly, high CE can be achieved when applied in both LiFePO4 full cells and Li-Cu half cells. This work offers a facile and efficient strategy to greatly promote CE in PEO-based ASSLBs.

In this study we synthesized Li-rich Li1.2Ni0.13Mn0.54Co0.13O2 (LMNCO) as a composite cathode material through a two-step spray-drying method, using transition metal (TM) acetates and citric acid (CA, as a chelating agent) at various molar ratios and then calcining at various temperatures for various periods of time. This two-step spray-drying method created hierarchical nano/micro-sphere structures of the LMNCO cathode material. The LMNCO cathode exhibited the best electrochemical performance when synthesized with a TM:CA ratio of 3:2, a calcination temperature of 900 °C, and a calcination time of 5 h. This as-prepared LMNCO composite was then modified with polyimide (PI) at various weight ratios (PI/LMNCO = 0.5, 1.0, and 1.5 wt%) to improve its electrochemical properties. Among the various structures, the LMNCO cathode material coated with 1.0 wt% of PI at a layer thickness of approximately 1.88 nm achieved the best initial discharge capacities. This modified electrode also displayed enhanced cycle stability, with over 93.3 and 87.9% of the capacity retained after 30 cycles at 0.1C and 100 cycles at 1C, respectively. In comparison, the capacity retention of the unmodified LMNCO electrode measured under the same conditions was no more than 91.3% at 0.1C and 70.1% at 1C. Thus, surface modification with PI was an effective method for improving the coulombic efficiency, discharge capacity, and long-term cycling performance of the LMNCO cathode. Such PI-coated LMNCO composite cathode materials appear to be potential candidates for use in next-generation high-performance lithium-ion batteries.

Heteroatom-doped carbon materials have demonstrated great potential in the electrochemical reduction reaction of CO2 (CO2RR) due to their versatile structure and function. However, rational structure control remains one challenge. In this work, we reported a unique carbon precursor of soft template-containing porous poly(ionic liquid) (PIL) that was directly synthesized via free-radical self-polymerization of ionic liquid monomer in a soft template route. Variation of the carbonization temperature in a direct pyrolysis process without any additive yielded a series of carbon materials with facile adjustable textural properties and N species. Significantly, the integration of soft-template in the PIL precursor led to the formation of hierarchical porous carbon material with a higher surface area and larger pore size than that from the template-free precursor. In CO2RR to CO, the champion catalyst gave a Faraday efficiency of 83.0% and a current density of 1.79 mA cm−2 at −0.9 V vs. reversible hydrogen electrode (vs. RHE). The abundant graphite N species and hierarchical pore structure, especially the unique hierarchical small-/ultra-micropores were revealed to enable better CO2RR performance.

Metallic lithium (Li) is known to consider a critical role in next-generation rechargeable batteries. However, the uncontrolled growth of Li dendrites result in low Coulombic efficiency and safety issues in applications of Li metal batteries. High capacity and stable dense deposits of lithium metal are of great significant for high energy density battery. Herein, we propose a suitable degree of substitution for Carboxymethylcellulose Lithium (CMC-Li) as an artificial SEI layer, which has a high ionic transference number (0.66), high Young's modulus (24.6 GPa) and good lithiophilicity, then it can adapt to the volume changes of the lithium anode, enable superdense lithium deposits on Cu collector. The metallic lithium anode with CMC-Li films (CMC-Li@Li) delivers excellent cycling performance in the symmetrical cell at a large current density of 10 mA cm−2 and an areal capacity of 10 mAh cm−2 for almost 300 h. Moreover, the CMC-Li@Li||NCM613 full cell (N/P=2) delivers an initial specific capacity of 165 mAh g−1 with a high retention of 80% after 200 cycles.

Despite having advantages of safety and dominating consumer and electric vehicle market, the progress of aqueous rechargeable battery research is hindered by low capacity anode materials. A game-changing strategy is to use an environmentally benign aqueous electrolyte with earth abundance Na-ion and sulfur. Sulfur promises to be a next-generation electrode material due to its high theoretical capacity and energy density. But the practical application of elemental sulfur in aqueous electrolyte suffer from sharp capacity decay due to the dissolution of polysulfides. Herein, we report 70 % elemental sulfur along with CoS2 and 1‑butyl‑3-methylimidazolium o,o-bis(2-ethylhexyl) dithiophosphate (BMIm-DDTP) ionic liquid (IL) as anode (S@CoS2-IL) for aqueous rechargeable sodium-ion/sulfur batteries (ARSSB) in 2 M aq. Na2SO4 electrolyte.The S@CoS2-IL anode delivers an outstanding capacity of 977 mA h g−1 (> 91 % of the theoretical capacity of elemental sulfur i.e. 1070 mA h g−1), at 0.5 C with a stable cycling performance over 100 cycles with > 98 % of capacity retention at 2 C with 100 % of coulombic efficiency. A negligible loss of S was confirmed by UV–Vis spectroscopy and potentiometric titration and anchoring of polysulfide at S@CoS2-IL anode were evidenced by NMR, ESI-mass, Raman and X-ray photoelectron spectroscopy. The synergy between highly active CoS2 and BMIm-DDTP IL from the dynamic coordination of dithiophosphate with CoS2 provides easy access for polysulfides anchoring and fast reaction kinetics which effectively suppresses the dissolution of discharge polysulfides and HS−. The full cell studies using S@CoS2-IL anode with standard Na0.44MnO2 cathode demonstrate an outstanding capacity of 778 mA h g−1 w.r.t the weight of S and 104.98 mA h g−1 (of total electrodes weight), which is close to the theoretical capacity of 109 mA h g−1 with 100 % coulombic efficiency and 91.8 % capacity retention over 400 cycles at 2 C. The excellent performance of this aqueous battery chemistry shows that S@CoS2-IL anode has great potential towards practical application in ARSSB.

The practical application of Lithium-sulfur (Li-S) batteries is significantly inhibited by (i) the notable ‘shuttle effect’ of lithium polysulfides (LiPS), (ii) the corrosion of the lithium interface, and (iii) the sluggish redox reaction kinetics. The functional separator in the Li-S battery has the potential to provide the perfect solution to these problems. Herein a triple-layer multifunctional PVDF-based nanofiber separator, which contains GoTiN/PVDF layer on the top and bottom and ZnTPP/PVDF layer on the middle, is designed. The polarity and porous structure of this multifunctional separator can greatly improve the wettability of electrolytes and enhance the transportation of Li+. With the zinc-based porphyrin framework (ZnTPP) structure, this separator has a strong chemisorption and LiPS conversion ability, which greatly prevent the ‘shuttle effect’. Consequently, the designed multilayer separator showed excellent electrochemical performance. As a result, the cell with GoTiN@ZnTPP@GoTiN nanofiber membrane displayed an initial discharge capacity of 1180 mAh/g with a benign capacity retention of 65.9% at 0.5 C and high coulombic efficiency of more than 98.5% after 100 cycles. Even at 2 C, it can still release a capacity of 798 mAh/g. Moreover, the remarkable capacity of 591 mAh/g could be achieved with a high sulfur load of 5.76 mg/cm2 under a current density of 0.1 C. Based on these merits, this novel and scalable multifunctional separator is a promising candidate to replace the conventional PP separator for advanced Li-S batteries to deal with various challenges.

The development of a conventional electrolyte, based on commercially available magnesium (Mg) salts in organic solvents, remains one of the most challenging quests for rechargeable Mg batteries. Conventional electrolytes typically form a passivation layer on Mg metal anode, necessitating the extensive use of inorganic chloride additives such as MgCl2. Herein, for the first time, we introduce an organic chloride, tetrabutylammonium chloride (TBAC), as a multifunctional electrolyte additive for conventional magnesium triflate (Mg(OTf)2)-based electrolytes. TBAC was found to perform three major roles: (1) enhance Mg(OTf)2 dissociation in aprotic solvent, (2) inhibit the reduction of triflate anions through surface-adsorbed TBA+, and (3) act as a chloride source to form Mg complexes and stabilize the Mg anode-electrolyte interface. The novel electrolyte combination of TBAC and Mg(OTf)2 in 1,2-dimethoxyethane exhibits excellent Mg plating/stripping with Coulombic efficiency of 97.7% over 200 cycles at 0.5 mA cm−2 and 0.5 mAh cm-2. Post-mortem analysis unveils uniform Mg deposition and stable solid electrolyte interphase formation on Mg anode, which enables reversible cycling with Mo6S8 cathode. Together with our findings on another organic chloride additive, 1-ethyl-3-methylimidazolium chloride, and in combination with different electrolyte salts and solvents, we showcase the general promise of high-performance conventional electrolytes for rechargeable Mg batteries.

The advancement of electrolyte systems has enabled the development of high-performance Li metal batteries (LMBs), which have tackled intractable dendritic Li growth and irreversible Li plating/stripping. In particular, the robust electrode–electrolyte interfaces created by electrolyte additives inhibit the deterioration of the cathode and the Li metal anode during repeated cycles. This paper reports the application of electrode–electrolyte interface modifiers, namely lithium nitrate (LiNO3) and lithium difluoro(bisoxalato) phosphate (LiDFBP) as a N donor and F donor, respectively. LiDFBP and LiNO3 with different electron-accepting abilities construct a mechanically robust, LiF-rich inner solid electrolyte interphase (SEI) and ion-permeable, Li3N-containing outer SEI layers on the Li metal anode, respectively. A well-structured dual-layer SEI capable of transporting Li+ ions is formed on the Li metal anode, while the cathode–electrolyte interface (CEI) on the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode is strengthened. Ether-based electrolytes containing LiDFBP and LiNO3 lead to a long cycle life (600 cycles) of Li|NCM811 full cells at C/2 with 80.9% capacity retention and a high Coulombic efficiency (CE) of 99.94%. Structural optimization of the SEI and CEI provides an opportunity for advancing the practical uses of LMBs.

The electrochemical conversion of nitric oxide (NO) to ammonia (NH3) provides a sustainable route to transform an air pollutant into a value-added chemical. However, the development of NO electroreduction remains hindered by the poor solubility in aqueous electrolytes, requiring the use of concentrated NO. Here, we report a dilute NO reduction using a gas diffusion electrode (GDE) to circumvent the mass transport issue. Through the incorporation of nanoscale zero-valent iron into carbon on the GDE, 96% NH3 Faradaic efficiency was achieved with 1% NO, and the computational calculations revealed that the Fe catalyzed the breaking of the N–O bond in the H2NO intermediate. The NH3 production rate was accelerated by controlling the concentration of protons in the electrolyte and reached 1,239 µmol cm-2h-1 with 10% NO. Our findings show that the gas-phase electrolysis of dilute NO can offer a practical option for upcycling the waste nitrogen.

Electrocatalytic N2 reduction reaction (NRR) provides a promising route for NH3 production under ambient conditions to replace traditional Haber-Bosch process. For this purpose, efficient NRR electrocatalysts with high NH3 yield rate and high Faradaic efficiency (FE) are required. Cu-based materials have been recognized catalytic active for some multi-electron-involved reduction reactions and usually exhibit inferior catalytic activities for hydrogen evolution reaction. We report here the preparation and characterization of a series of Cu-based nanowires array (NA) catalysts in situ grown on Cu foam (CF) substrate, including Cu(OH)2 NA/CF, Cu3N NA/CF, Cu3P NA/CF, CuO NA/CF and Cu NA/CF, which are directly used as self-supported catalytic electrodes for NRR. The electrochemical results show that CuO NA/CF achieves a highest NH3 yield rate of 1.84 × 10−9 mol s−1 cm−2, whereas Cu NA/CF possesses a highest FE of 18.2% for NH3 production at -0.1 V versus reversible hydrogen electrode in 0.1 M Na2SO4. Such catalytic performances are superior to most of recently reported metal-based NRR electrocatalysts. The contact angle measurements and the simulated calculations are carried out to reveal the important role of the superaerophobic NA surface structure for efficient NRR electrocatalysis.