Regulating the reduction reaction pathways via manipulating the solvation shell and donor number of the solvent in Li-CO2 chemistry.

Transforming CO2 into valuable chemicals is an inevitable trend in our current society. Among the viable end-uses of CO2, fixing CO2 as carbon or carbonates via Li-CO2 chemistry could be an efficient approach, and promising achievements have been obtained in catalyst design in the past. Even so, the critical role of anions/solvents in the formation of a robust solid electrolyte interphase (SEI) layer on cathodes and the solvation structure have never been investigated. Herein, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in two common solvents with various donor numbers (DN) have been introduced as ideal examples. The results indicate that the cells in dimethyl sulfoxide (DMSO)-based electrolytes with high DN possess a low proportion of solvent-separated ion pairs and contact ion pairs in electrolyte configuration, which are responsible for fast ion diffusion, high ionic conductivity, and small polarization. The 3 M DMSO cell delivered the lowest polarization of 1.3 V compared to all the tetraethylene glycol dimethyl ether (TEGDME)-based cells (about 1.7 V). In addition, the coordination of the O in the TFSI- anion to the central solvated Li+ ion was located at around 2 Å in the concentrated DMSO-based electrolytes, indicating that TFSI- anions could access the primary solvation sheath to form an LiF-rich SEI layer. This deeper understanding of the electrolyte solvent property for SEI formation and buried interface side reactions provides beneficial clues for future Li-CO2 battery development and electrolyte design.

Progress and perspectives on iron-based electrode materials for alkali metal-ion batteries: a critical review.

Iron-based materials with significant physicochemical properties, including high theoretical capacity, low cost and mechanical and thermal stability, have attracted research attention as electrode materials for alkali metal-ion batteries (AMIBs). However, practical implementation of some iron-based materials is impeded by their poor conductivity, large volume change, and irreversible phase transition during electrochemical reactions. In this review we critically assess advances in the chemical synthesis and structural design, together with modification strategies, of iron-based compounds for AMIBs, to obviate these issues. We assess and categorize structural and compositional regulation and its effects on the working mechanisms and electrochemical performances of AMIBs. We establish insight into their applications and determine practical challenges in their development. We provide perspectives on future directions and likely outcomes. We conclude that for boosted electrochemical performance there is a need for better design of structures and compositions to increase ionic/electronic conductivity and the contact area between active materials and electrolytes and to obviate the large volume change and low conductivity. Findings will be of interest and benefit to researchers and manufacturers for sustainable development of advanced rechargeable ion batteries using iron-based electrode materials.

Boron-Modulated Electronic-Configuration Tuning of Cobalt for Enhanced Nitric Oxide Fixation to Ammonia.

Electrocatalytic nitric oxide reduction (eNORR) to ammonia (NH3) provides an environmental route to alleviate NO pollution and yield great-value chemicals. The evolution of eNORR has been primarily hindered, however, by the poor reaction kinetics and low solubility of the NO in aqueous electrolytes. Herein, we have rationally designed a cobalt-based composite with a heterostructure as a highly efficient eNORR catalyst. In addition, by integrating boron to modulate the electronic structure, the catalyst CoB/Co@C delivered a significant NH3 yield of 315.4 µmol h-1 cm-2 for eNORR and an outstanding power density of 3.68 mW cm-2 in a Zn-NO battery. The excellent electrochemical performance of CoB/Co@C is attributed to the enrichment of NO by cobalt and boron dual-site adsorption and fast charge-transfer kinetics. It is demonstrated that the boron is pivotal in the enhancement of NO, the suppression of hydrogen evolution, and Co oxidation to boost eNORR performance.

Boosted Mg-CO2 Batteries by Amine-Mediated CO2 Capture Chemistry and Mg2+ -Conducting Solid-electrolyte Interphases.

Mg-CO2 battery has been considered as an ideal system for energy conversion and CO2 fixation. However, its practical application is significantly limited by the poor reversibility and sluggish kinetics of CO2 cathode and Mg anode. Here, a new amine mediated chemistry strategy is proposed to realize a highly reversible and high-rate Mg-CO2 battery in conventional electrolyte. Judiciously combined experimental characterization and theoretical computation unveiled that the introduced amine could simultaneously modify the reactant state of CO2 and Mg2+ to accelerate CO2 cathodic reactions on the thermodynamic-kinetic levels and facilitate the formation of Mg2+ -conductive solid-electrolyte interphase (SEI) to enable highly reversible Mg anode. As a result, the Mg-CO2 battery exhibits boosted stable cyclability (70 cycles, more than 400 h at 200 mA g-1 ) and high-rate capability (from 100 to 2000 mA g-1 with 1.5 V overpotential) even at -15 °C. This work opens a newly promising avenue for advanced metal-CO2 batteries.

Tunable Interfacial Electric Field-Mediated Cobalt-Doped FeSe/Fe3Se4 Heterostructure for High-Efficiency Potassium Storage.

The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium-ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high-efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon-coated undifferentiated cobalt-doped FeSe/Fe3Se4 heterostructure (denoted UN-CoFe4Se5/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/Fe3Se4, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN-CoFe4Se5/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon-coated FeSe/Fe3Se4 heterostructure (Fe4Se5/C). Benefiting from the strong IEF, UN-CoFe4Se5/C as a PIB anode exhibits superior rate capability (145.8 mAh g-1 at 10.0 A g-1) and long cycle lifespan (capacity retention of 95.1 % over 3000 cycles at 1.0 A g-1). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe2/Co9Se8 and FeS2/Fe7S8 heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.

Zinc ion Batteries: Bridging the Gap from Academia to Industry for Grid-Scale Energy Storage.

Zinc ion batteries (ZIBs) exhibit significant promise in the next generation of grid-scale energy storage systems owing to their safety, relatively high volumetric energy density, and low production cost. Despite substantial advancements in ZIBs, a comprehensive evaluation of critical parameters impacting their practical energy density (Epractical) and calendar life is lacking. Hence, we suggest using formulation-based study as a scientific tool to accurately calculate the cell-level energy density and predict the cycling life of ZIBs. By combining all key battery parameters, such as the capacity ratio of negative to positive electrode (N/P), into one formula, we assess their impact on Epractical. When all parameters are optimized, we urge to achieve the theoretical capacity for a high Epractical. Furthermore, we propose a formulation that correlates the N/P and Coulombic efficiency of ZIBs for predicting their calendar life. Finally, we offer a comprehensive overview of current advancements in ZIBs, covering cathode and anode, along with practical evaluations. This Minireview outlines specific goals, suggests future research directions, and sketches prospects for designing efficient and high-performing ZIBs. It aims at bridging the gap from academia to industry for grid-scale energy storage.

Sulfonyl Molecules Induced Oriented Lithium Deposition for Long-Term Lithium Metal Batteries.

Dendrites growth and unstable interfacial Li+ transport hinder the practical application of lithium metal batteries (LMBs). Herein, we report an active layer of 2,4,6-trihydroxy benzene sulfonyl fluorine on copper substrate that induces oriented Li+ deposition and generates highly crystalline solid-electrolyte interphase (SEI) to achieve high-performance LMBs. The lithiophilic -SO2 - groups of highly crystalline SEI accept the rapidly transported Li+ ions and form a dense inner layer of LiF and Li3 N, which regulate Li+ plating morphology along the (110) crystal surface toward dendrite-free Li anode. Thus, Li||Cu cells with lithiophilic SEI achieve an average deposition efficiency of 99.8 % after 700 cycles, and Li||Li cells operate well for 1100 h. Besides, Li||LiNi0.8 Co0.1 Mn0.1 O2 cells with modified SEI exhibit a capacity retention that is 14 times than that of conventional SEI. Even at -60 °C, Li||Cu cells reach stable deposition efficiency of 83.2 % after 100 cycles.

Interfacial Engineering of Zn Metal via a Localized Conjugated Layer for Highly Reversible Aqueous Zinc Ion Battery.

Aqueous zinc-ion batteries are regarded as promising and efficient energy storage systems owing to remarkable safety and satisfactory capacity. Nevertheless, the instability of zinc metal anodes, characterized by issues such as dendrite growth and parasitic side reactions, poses a significant barrier to widespread applications. Herein, we address this challenge by designing a localized conjugated structure comprising a cyclic polyacrylonitrile polymer (CPANZ), induced by a Zn2+-based Lewis acid (zinc trifluoromethylsulfonate) at a temperature of 120 °C. The CPANZ layer on the Zn anode, enriched with appropriate pyridine nitrogen-rich groups (conjugated cyclic -C=N-), exhibits a notable affinity for Zn2+ with ample deposition sites. This zincophilic skeleton not only serves as a protective layer to guide the deposition of Zn2+ but also functions as proton channel blocker, regulating the proton flux to mitigate the hydrogen evolution. Additionally, the strong adhesion strength of the CPANZ layer guarantees its sustained protection to the Zn metal during long-term cycling. As a result, the modified zinc electrode demonstrates long cycle life and high durability in both half-cell and pouch cells. These findings present a feasible approach to designing high performance aqueous anodes by introducing a localized conjugated layer.

Structural Distortion in the Wadsley-Roth Niobium Molybdenum Oxide Phase Triggering Extraordinarily Stable Battery Performance.

Wadsley-Roth niobium oxide phases have attracted extensive research interest recently as promising battery anodes. We have synthesized the niobium-molybdenum oxide shear phase (Nb, Mo)13 O33 with superior electrochemical Li-ion storage performance, including an ultralong cycling lifespan of at least 15000 cycles. During electrochemical cycling, a reversible single-phase solid-solution reaction with lithiated intermediate solid solutions is demonstrated using in situ X-ray diffraction, with the valence and short-range structural changes of the electrode probed by in situ Nb and Mo K-edge X-ray absorption spectroscopy. This work reveals that the superior stability of niobium molybdenum oxides is underpinned by changes in octahedral distortion during electrochemical reactions, and we report an in-depth understanding of how this stabilizes the oxide structure during cycling with implications for future long-life battery material design.

An Ultra-Stable Electrode-Solid Electrolyte Composite for High-Performance All-Solid-State Li-Ion Batteries.

The low ionic and electronic conductivity between current solid electrolytes and high-capacity anodes limits the long-term cycling performance of all-solid-state lithium-ion batteries (ASSLIBs). Herein, this work reports the fabrication of an ultra-stable electrode-solid electrolyte composite for high-performance ASSLIBs enabled by the homogeneous coverage of ultrathin Mg(BH4 )2 layers on the surface of each MgH2 nanoparticle that are uniformly distributed on graphene. The initial discharge process of Mg(BH4 )2 layers results in uniform coverage of MgH2 nanoparticle with both LiBH4 as the solid electrolyte and Li2 B6 with even higher Li ion conductivity than LiBH4 . Consequently, the Li ion conductivity of graphene-supported MgH2 nanoparticles covered with ultrathin Mg(BH4 )2 layers is two orders of magnitude higher than that without Mg(BH4 )2 layers. Moreover, the thus-formed inactive Li2 B6 with strong adsorption capability toward LiBH4 , acts as a stabilizing framework, which, coupled with the structural support role of graphene, alleviates the volume change of MgH2 nanoparticles and facilitates the intimate contact between LiBH4 and individual MgH2 nanoparticles, leading to the formation of uniform stable interfaces with high ionic and electronic conductivity on each MgH2 nanoparticles. Hence, an ultrahigh specific capacity of 800 mAh g-1 is achieved for MgH2 at 2 A g-1 after 350 cycles.

Electrolyte Engineering on Performance Enhancement of NiCo2 S4 Anode for Sodium Storage.

NiCo2 S4 is an attractive anode for sodium-ion batteries (SIBs) due to its high capacity and excellent redox reversibility. Practical deployment of NiCo2 S4 electrode in SIBs, however, is still hindered by the inferior capacity and unsatisfactory cycling performance, which result from the mismatch between the electrolyte chemistry and electrode. Herein, a functional electrolyte containing 1.0 m NaCF3 SO3 in diethylene glycol dimethyl ether (DEGDME) (1.0 m NaCF3 SO3 -DEGDME) is developed, which can be readily used for NiCo2 S4 anode with high initial coulomb efficiency (96.2%), enhanced cycling performance, and boosted capacities (341.7 mA h g-1 after 250 continuous cycles at the current density of 200 mA g-1 ). The electrochemical tests and related phase characterization combined with density functional theory (DFT) calculation indicate the ether-based electrolyte is more suitable for the NiCo2 S4 anode in SIBs due to the formation of a stable electrode-electrolyte interface. Additionally, the importance of the voltage window is also demonstrated to further optimize the electrochemical performance of the NiCo2 S4 electrode. The formation of sulfide intermediates during charging and discharging is predicted by combining DFT and verified by in situ XRD and HRTEM. The findings indicate that electrolyte engineering would be an effective way of performance enhancement for sulfides in practical SIBs.

Molybdenum Atom Engineered Vanadium Disulfide for Boosted High-Capacity Li-Ion Storage.

A drawback with lithium-ion batteries (LIBs) lies in the unstable lithium storage which results in poor electrochemical performance. Therefore, it's of importance to improve the electrochemical functionality and Li-ion transport kinetics of electrode materials for high-performance lithium storage. Here, a subtle atom engineering via injecting molybdenum (Mo) atoms into vanadium disulfide (VS2 ) to boost high capacity Li-ion storage is reported. By combining operando, ex situ monitoring and theoretical simulation, it is confirmed that the 5.0%Mo atoms impart flower-like VS2 with expanded interplanar spacing, lowered Li-ion diffusion energy barrier, and increased Li-ion adsorption property, together with enhanced e- conductivity, to boost Li-ion migration. A "speculatively" optimized 5.0% Mo-VS2 cathode that exhibits a specific capacity of 260.8 mA h g-1 at 1.0 A g-1 together with a low decay of 0.009% per cycle over 500 cycles is demonstrated. It is shown that this value is ≈1.5 times compared with that for bare VS2 cathode. This investigation has substantiated the Mo atom doping can effectively guide the Li-ion storage and open new frontiers for exploiting high-performance transition metal dichalcogenides for LIBs.

Designing a hybrid electrode toward high energy density with a staged Li+ and PF6 - deintercalation/intercalation mechanism.

Existing lithium-ion battery technology is struggling to meet our increasing requirements for high energy density, long lifetime, and low-cost energy storage. Here, a hybrid electrode design is developed by a straightforward reengineering of commercial electrode materials, which has revolutionized the "rocking chair" mechanism by unlocking the role of anions in the electrolyte. Our proof-of-concept hybrid LiFePO4 (LFP)/graphite electrode works with a staged deintercalation/intercalation mechanism of Li+ cations and PF6 - anions in a broadened voltage range, which was thoroughly studied by ex situ X-ray diffraction, ex situ Raman spectroscopy, and operando neutron powder diffraction. Introducing graphite into the hybrid electrode accelerates its conductivity, facilitating the rapid extraction/insertion of Li+ from/into the LFP phase in 2.5 to 4.0 V. This charge/discharge process, in turn, triggers the in situ formation of the cathode/electrolyte interphase (CEI) layer, reinforcing the structural integrity of the whole electrode at high voltage. Consequently, this hybrid LFP/graphite-20% electrode displays a high capacity and long-term cycling stability over 3,500 cycles at 10 C, superior to LFP and graphite cathodes. Importantly, the broadened voltage range and high capacity of the hybrid electrode enhance its energy density, which is leveraged further in a full-cell configuration.

Work-Function-Induced Interfacial Electron/Ion Transport in Carbon Hosts toward Dendrite-Free Lithium Metal Anodes.

Coupled electron/ion transport is a decisive feature of Li plating/stripping, wherein the compatibility of electron/ion transport rates determines the morphology of deposited Li. Local Li+ hotspots form due to inhomogeneous interfacial charge transfer and lead to uncontrolled Li deposition, which decreases the Li utilization rate and safety of Li metal anodes. Herein, we report a method to obtain dendrite-free Li metal anodes by driving electron pumping and accumulating and boosting Li ion diffusion by tuning the work function of a carbon host using cobalt-containing catalysts. The results reveal that increasing the work function provides an electron deviation from C to Co, and electron-rich Co shows favorable binding to Li+ . The Co catalysts boost Li+ diffusion on the carbon fiber scaffolds without local aggregation by reducing the Li+ migration barrier. The as-obtained dendrite-free Li metal anode exhibits a Coulombic efficiency of 99.0 %, a cycle life of over 2000 h, a Li utilization rate of 50 %, and a capacity retention of 83.4 % after 130 cycles in pouch cells at a negative/positive capacity ratio of 2.5. These findings provide a novel strategy to stabilize Li metal by regulating the work function of materials using electrocatalysts.

Carbon Electrode Materials for Advanced Potassium-Ion Storage.

Tremendous progress has been made in the field of electrochemical energy storage devices that rely on potassium-ions as charge carriers due to their abundant resources and excellent ion transport properties. Nevertheless, future practical developments not only count on advanced electrode materials with superior electrochemical performance, but also on competitive costs of electrodes for scalable production. In the past few decades, advanced carbon materials have attracted great interest due to their low cost, high selectivity, and structural suitability and have been widely investigated as functional materials for potassium-ion storage. This article provides an up-to-date overview of this rapidly developing field, focusing on recent advanced and mechanistic understanding of carbon-based electrode materials for potassium-ion batteries. In addition, we also discuss recent achievements of dual-ion batteries and conversion-type K-X (X=O2 , CO2 , S, Se, I2 ) batteries towards potential practical applications as high-voltage and high-power devices, and summarize carbon-based materials as the host for K-metal protection and possible directions for the development of potassium energy-related devices as well. Based on this, we bridge the gaps between various carbon-based functional materials structure and the related potassium-ion storage performance, especially provide guidance on carbon material design principles for next-generation potassium-ion storage devices.

Monolithic Phosphate Interphase for Highly Reversible and Stable Zn Metal Anode.

Zinc metal battery (ZMB) is promising as the next generation of energy storage system, but challenges relating to dendrites and corrosion of the zinc anode are restricting its practical application. Here, to stabilize Zn anode, we report a controlled electrolytic method for a monolithic solid-electrolyte interphase (SEI) via a high dipole moment solvent dimethyl methylphosphonate (DMMP). The DMMP-based electrolytes can generate a homogeneous and robust phosphate SEI (Zn3 (PO4 )2 and ZnP2 O6 ). Benefiting from the protecting impact of this in situ monolithic SEI, the zinc electrode exhibits long-term cycling of 4700 h and a high Coulombic efficiency 99.89 % in Zn|Zn and Zn|Cu cell, respectively. The full V2 O5 |Zn battery with DMMP-H2 O hybrid electrolyte exhibits a high capacity retention of 82.2 % following 4000 cycles under 5 A g-1 . The first success in constructing the monolithic phosphate SEI will open a new avenue in electrolyte design for highly reversible and stable Zn metal anodes.

Catalytic Chemistry Derived Artificial Solid Electrolyte Interphase for Stable Lithium Metal Anodes Working at 20†mA cm-2 and 20†mAh cm-2.

A stable solid electrolyte interphase (SEI) layer is crucial for lithium metal anode (LMA) to survive in long-term cycling. However, chaotic structures and chemical inhomogeneity of natural SEI make LMA suffering from exasperating dendrite growth and severe electrode pulverization, which hinder the practical application of LMAs. Here, we design a catalyst-derived artificial SEI layer with an ordered polyamide-lithium hydroxide (PA-LiOH) bi-phase structure to modulate ion transport and enable dendrite-free Li deposition. The PA-LiOH layer can substantially suppress the volume changes of LMA during Li plating/stripping cycles, as well as alleviate the parasitic reactions between LMA and electrolyte. The optimized LMAs demonstrate excellent stability in Li plating/stripping cycles for over 1000 hours at an ultra-high current density of 20 mA cm-2 in Li||Li symmetric cells. A high coulombic efficiency up to 99.2 % in Li half cells in additive-free electrolytes is achieved even after 500 cycles at a current density of 1 mA cm-2 with a capacity of 1 mAh cm-2 .

Organic pH Buffer for Dendrite-Free and Shuttle-Free Zn-I2 Batteries.

Aqueous Zn-Iodine (I2 ) batteries are attractive for large-scale energy storage. However, drawbacks include, Zn dendrites, hydrogen evolution reaction (HER), corrosion and, cathode "shuttle" of polyiodines. Here we report a class of N-containing heterocyclic compounds as organic pH buffers to obviate these. We evidence that addition of pyridine /imidazole regulates electrolyte pH, and inhibits HER and anode corrosion. In addition, pyridine and imidazole preferentially absorb on Zn metal, regulating non-dendritic Zn plating /stripping, and achieving a high Coulombic efficiency of 99.6 % and long-term cycling stability of 3200 h at 2 mA cm-2 , 2 mAh cm-2 . It is also confirmed that pyridine inhibits polyiodines shuttling and boosts conversion kinetics for I- /I2 . As a result, the Zn-I2 full battery exhibits long cycle stability of >25 000 cycles and high specific capacity of 105.5 mAh g-1 at 10 A g-1 . We conclude organic pH buffer engineering is practical for dendrite-free and shuttle-free Zn-I2 batteries.

Stabilizing Cobalt-free Li-rich Layered Oxide Cathodes through Oxygen Lattice Regulation by Two-phase Ru Doping.

The application of Li-rich layered oxides is hindered by their dramatic capacity and voltage decay on cycling. This work comprehensively studies the mechanistic behaviour of cobalt-free Li1.2 Ni0.2 Mn0.6 O2 and demonstrates the positive impact of two-phase Ru doping. A mechanistic transition from the monoclinic to the hexagonal behaviour is found for the structural evolution of Li1.2 Ni0.2 Mn0.6 O2, and the improvement mechanism of Ru doping is understood using the combination of in operando and post-mortem synchrotron analyses. The two-phase Ru doping improves the structural reversibility in the first cycle and restrains structural degradation during cycling by stabilizing oxygen (O2- ) redox and reducing Mn reduction, thus enabling high structural stability, an extraordinarily stable voltage (decay rate <0.45 mV per cycle), and a high capacity-retention rate during long-term cycling. The understanding of the structure-function relationship of Li1.2 Ni0.2 Mn0.6 O2 sheds light on the selective doping strategy and rational materials design for better-performance Li-rich layered oxides.

Electrolyte Engineering Enables High Performance Zinc-Ion Batteries.

Zinc-ion batteries (ZIBs) feature high safety, low cost, environmental-friendliness, and promising electrochemical performance, and are therefore regarded as a potential technology to be applied in large-scale energy storage devices. However, ZIBs still face some critical challenges and bottlenecks. The electrolyte is an essential component of batteries and its properties affect the mass transport, energy storage mechanisms, reaction kinetics, and side reactions of ZIBs. The adjustment of electrolyte formulas usually has direct and obvious impacts on the overall output and performance. In this review, advanced electrolyte strategies are overviewed for optimizing the compatibility between cathode materials and electrolytes, inhibiting anode corrosion and dendrite growth, extending electrochemical stability windows, enabling wearable applications, and enhancing temperature tolerance. The underlying scientific mechanisms, electrolyte design principles, and recent progress are presented to provide a better understanding and inspiration to readers. In addition, a comprehensive perspective about electrolyte design and engineering for ZIBs is included.