Deep eutectic solvents (DESs) are a large family of solvents that show many similarities with ionic liquids. They are distinguished by the presence of a large amount of molecular components ...(typically hydrogen bond donors). They are more industrially promising than ionic liquids due to their low cost and tolerance to humidity (hydrolysis or hygroscopicity). As an emerging research field, DESs have already received significant research attention from chemistry scientists. The exploration of DESs used for functional materials in energy and environmental applications is still in its early stage. This review briefly introduces the basics of DESs and how they could be promising as solvents for material scientists. We summarized the application of DESs for the synthesis of materials used for energy and environmental applications. In this review, DESs have been described in view of the three main roles they play in the solution process of functional materials. Besides DESs being widely known as inert media or reactive reagents for the synthesis of materials, they can also be directly adopted as functional materials such as electrolytes for energy storage devices or as CO
2
adsorbents. The present review focused on several categories of functional materials including noble metals, porous carbonaceous materials, transition metal compounds, and DESs themselves, which are synthesized or derived from DESs for potential applications in the energy and environmental fields. DESs have been demonstrated to be effective in guiding the formation of functional materials with unique structures and properties. In particular, we introduced our work on exploring a DES-thermal synthesis strategy, in which the DES is used as a solvent as well as a reagent. Recent theoretical and experimental work for understanding the structural basis of DESs has also been summarized. This review article aims to inspire scientists to use DESs as a powerful tool to push the frontiers in the field of materials, energy, and environmental science.
This review aims to inspire more researchers to explore potential energy and environmental applications of DESs and their derivatives.
Lithium metal batteries (LMB) are recognized as the most promising high-energy-density energy storage devices. However, its large-scale commercial applications are seriously hampered by the poor ...cycling stability and potential safety issues. Solid electrolyte interphase (SEI) acts a dominant role in influencing the regulation of Li deposition and overall performance of LMBs, but the composition as well as the evolution of SEI remain quite elusive. Advanced characterization methods and operando monitoring techniques are urgently required. Herein, in this perspective, we first briefly introduce the development history of SEI research and the SEI formation mechanisms as well as the common known components of SEI. Then, we focus on several recent advanced technologies for SEI characterization and monitoring, and the corresponding study cases will be presented. In the end, perspectives including the future investigation directions, the in situ characterization methods, and the component-performance associated model are proposed. We believe that this timely review will help to give a comprehensive understanding on the up-to-date SEI characterization tools.
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A new and generic strategy to construct interwoven carbon nanotube (CNT) branches on various metal oxide nanostructure arrays (exemplified by V2O3 nanoflakes, Co3O4 nanowires, Co3O4–CoTiO3 composite ...nanotubes, and ZnO microrods), in order to enhance their electrochemical performance, is demonstrated for the first time. In the second part, the V2O3/CNTs core/branch composite arrays as the host for Na+ storage are investigated in detail. This V2O3/CNTs hybrid electrode achieves a reversible charge storage capacity of 612 mAh g−1 at 0.1 A g−1 and outstanding high‐rate cycling stability (a capacity retention of 100% after 6000 cycles at 2 A g−1, and 70% after 10 000 cycles at 10 A g−1). Kinetics analysis reveals that the Na+ storage is a pseudocapacitive dominating process and the CNTs improve the levels of pseudocapacitive energy by providing a conductive network.
Chemical vapor deposition synthesis of carbon nanotube (CNT) branches is demonstrated on four types of metal oxide arrays. High‐performance Na ion storage is proven in the V2O3/CNTs system long cycle stability and high rates.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
All-solid-state lithium batteries (ASSLIBs) employing sulfide solid electrolyte hold high promise to replace traditional liquid-electrolyte LIBs due to their high safety and energy density. However, ...Li dendritic growth in sulfide electrolyte limits the realization of the high energy of ASSLIBs. In this work, we use LiF (or LiI) layer at the interface between Li and sulfide electrolyte and penetrated HFE (or I solution) inside of sulfide electrolyte to suppress the Li dendrite growth. Due to the higher interface energy of LiF/Li than that of LiI/Li, LiF interlayer show much higher capability than LiI in suppressing the Li dendrite. Even if the Li dendrite breaks through LiF (or LiI) interlayer, the Li dendrites will be consumed by coated/penetrated HEF (or I) forming LiF (or LiI) thus preventing Li dendrite growth. A LiNbO3 @LiCoO2/Li7P3S11/Li ASSLIB employing HFE coated/infiltrated Li7P3S11 glass-ceramic as electrolyte, and LiF coated Li metal as anode shows a high reversible discharge capacity of 118.9 mAh g−1 at 0.1 mA cm−2 and retains 96.8 mAh g−1 after 100 cycles. The designed solid electrolyte interphase between Li and solid electrolyte that has a high interface energy to Li provides new opportunity to commercialize the Li metal batteries.
We demonstrate that a uniform the LiF (or LiI) interfacial layer at Li/Li7P3S11 interface and infiltration of HFE (or I solution) into sulfide electrolyte can suppress the Li dendrite growth. Due to the modification, the assembled Li@LiF/Li7P3S11/LiF@Li symmetrical cell can stably plating/stripping at 0.5 mA cm−2 and 0.1 mAh cm−2 at 25 °C for over 200 cycles. Coupled with the LNO-LCO cathode, the all-solid-state Li@LiF/Li7P3S11/LNO@LCO full cell exhibits a high initial reversible capacity of 118.9 mAh g−1 with excellent cycling stability and high rate performances at room temperature. Display omitted
•Rational coating of LiF (or LiI) on Li enables stable interface.•Infiltrating HFE (or I) into electrolytes suppresses the growth of Li dendrites.•High interface energy of LiF/Li promotes a uniform Li deposition.•High electrochemical performance was achieved for the cell with Li@LiF and HFE.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Scrupulous design and smart hybridization of bespoke electrode materials are of great importance for the advancement of sodium ion batteries (SIBs). Graphene‐based nanocomposites are regarded as one ...of the most promising electrode materials for SIBs due to the outstanding physicochemical properties of graphene and positive synergetic effects between graphene and the introduced active phase. In this review, the recent progress in graphene‐based electrode materials for SIBs with an emphasis on the electrode design principle, different preparation methods, and mechanism, characterization, synergistic effects, and their detailed electrochemical performance is summarized. General design rules for fabrication of advanced SIB materials are also proposed. Additionally, the merits and drawbacks of different fabrication methods for graphene‐based materials are briefly discussed and summarized. Furthermore, multiscale forms of graphene are evaluated to optimize electrochemical performance of SIBs, ranging from 0D graphene quantum dots, 2D vertical graphene and reduced graphene oxide sheets, to 3D graphene aerogel and graphene foam networks. To conclude, the challenges and future perspectives on the development of graphene‐based materials for SIBs are also presented.
The recent progress of multiscale graphene‐based electrode materials for application in sodium ion batteries in respect of electrode design principle, preparation methods, characterization, synergistic effects, and electrochemical performance is reviewed, and future challenges and prospects of the field are presented.
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Exploring advanced battery materials with fast charging/discharging capability is of great significance to the development of modern electric transportation. Herein we report a powerful synergistic ...engineering of carbon and deficiency to construct high-quality three/two-dimensional cross-linked Ti
Nb
O
@C composites at primary grain level with conformal and thickness-adjustable boundary carbon. Such exquisite boundary architecture is demonstrated to be capable of regulating the mechanical stress and concentration of oxygen deficiency for desired performance. Consequently, significantly improved electronic conductivity and enlarged lithium ion diffusion path, shortened activation process and better structural stability are realized in the designed Ti
Nb
O
@C composites. The optimized Ti
Nb
O
@C composite electrode shows fast charging/discharging capability with a high capacity of 197 mA h g
at 20 C (∼3 min) and excellent long-term durability with 98.7% electron and Li capacity retention over 500 cycles. Most importantly, the greatest applicability of our approach has been demonstrated by various other metal oxides, with tunable morphology, structure and composition.
In carbonate electrolytes, the organic–inorganic solid electrolyte interphase (SEI) formed on the Li‐metal anode surface is strongly bonded to Li and experiences the same volume change as Li, thus it ...undergoes continuous cracking/reformation during plating/stripping cycles. Here, an inorganic‐rich SEI is designed on a Li‐metal surface to reduce its bonding energy with Li metal by dissolving 4m concentrated LiNO3 in dimethyl sulfoxide (DMSO) as an additive for a fluoroethylene‐carbonate (FEC)‐based electrolyte. Due to the aggregate structure of NO3− ions and their participation in the primary Li+ solvation sheath, abundant Li2O, Li3N, and LiNxOy grains are formed in the resulting SEI, in addition to the uniform LiF distribution from the reduction of PF6− ions. The weak bonding of the SEI (high interface energy) to Li can effectively promote Li diffusion along the SEI/Li interface and prevent Li dendrite penetration into the SEI. As a result, our designed carbonate electrolyte enables a Li anode to achieve a high Li plating/stripping Coulombic efficiency of 99.55 % (1 mA cm−2, 1.0 mAh cm−2) and the electrolyte also enables a Li||LiNi0.8Co0.1Mn0.1O2 (NMC811) full cell (2.5 mAh cm−2) to retain 75 % of its initial capacity after 200 cycles with an outstanding CE of 99.83 %.
An inorganic‐rich solid electrolyte interphase (SEI) has been constructed on Li metal to promote dense Li growth with a Coulombic efficiency of 99.55 % in the carbonate electrolyte. It was synthesized on the surface of the Li‐metal anode using concentrated LiNO3 in dimethyl sulfoxide (DMSO) as an additive in the FEC‐based electrolyte, which participates in the primary Li+ solvation shell and promotes the reduction of NO3− ions to form the inorganic‐rich SEI.
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The high performance of a pseudocapacitor electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. We present a powerful two-step ...solution-based method for the fabrication of transition metal oxide core/shell nanostructure arrays on various conductive substrates. Demonstrated examples include Co3O4 or ZnO nanowire core and NiO nanoflake shells with a hierarchical and porous morphology. The “oriented attachment” and “self-assembly” crystal growth mechanisms are proposed to explain the formation of the NiO nanoflake shell. Supercapacitor electrodes based on the Co3O4/NiO nanowire arrays on 3D macroporous nickel foam are thoroughly characterized. The electrodes exhibit a high specific capacitance of 853 F/g at 2 A/g after 6000 cycles and an excellent cycling stability, owing to the unique porous core/shell nanowire array architecture, and a rational combination of two electrochemically active materials. Our growth approach offers a new technique for the design and synthesis of transition metal oxide or hydroxide hierarchical nanoarrays that are promising for electrochemical energy storage, catalysis, and gas sensing applications.
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Engineering a stable solid electrolyte interphase (SEI) is critical for suppression of lithium dendrites. However, the formation of a desired SEI by formulating electrolyte composition is very ...difficult due to complex electrochemical reduction reactions. Here, instead of trial-and-error of electrolyte composition, we design a Li-11 wt % Sr alloy anode to form a SrF2-rich SEI in fluorinated electrolytes. Density functional theory (DFT) calculation and experimental characterization demonstrate that a SrF2-rich SEI has a large interfacial energy with Li metal and a high mechanical strength, which can effectively suppress the Li dendrite growth by simultaneously promoting the lateral growth of deposited Li metal and the SEI stability. The Li–Sr/Cu cells in 2 M LiFSI-DME show an outstanding Li plating/stripping Coulombic efficiency of 99.42% at 1 mA cm–2 with a capacity of 1 mAh cm–2 and 98.95% at 3 mA cm–2 with a capacity of 2 mAh cm–2, respectively. The symmetric Li–Sr/Li–Sr cells also achieve a stable electrochemical performance of 180 cycles at an extremely high current density of 30 mA cm–2 with a capacity of 1 mAh cm–2. When paired with LiFePO4 (LFP) and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes, Li–Sr/LFP cells in 2 M LiFSI-DME electrolytes and Li–Sr/NMC811 cells in 1 M LiPF6 in FEC:FEMC:HFE electrolytes also maintain excellent capacity retention. Designing SEIs by regulating Li-metal anode composition opens up a new and rational avenue to suppress Li dendrites.
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We report a procedure to fabricate nanostructured Ni films via programmed electrochemical deposition from a choline-chloride-based ionic liquid at a high temperature of 90 °C. Three electrodeposition ...modes using constant voltage, pulse voltage, and reverse pulse voltage produce a variety of nanostructured Ni films with micro/nanobinary surface architectures, such as nanosheets, aligned nanostrips, and hierarchical flowers. The nanostructured Ni films possess face-centered cubic crystal structure. Amazingly, it is found that the electrodeposited Ni films deliver the superhydrophobic surfaces without any further modifications by low surface-energy materials, which might be attributed to the vigorous micro/nanobinary architectures and the surface chemical composition. The electrochemical measurements reveal that the superhydrophobic Ni film exhibit an obvious passivation phenomenon, which could provide enhanced corrosion resistance for the substrate in the aqueous solutions.
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