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Metallic Zn is considered as a promising anode material because of its abundance, eco-friendliness, and high theoretical capacity. However, the uncontrolled dendrite growth and side reactions restrict its further practical application. Herein, we proposed a ß-cyclodextrin-modified multiwalled carbon nanotube (CD-MWCNT) layer for Zn metal anodes. The obtained CD-MWCNT layer with high affinity to Zn can significantly reduce the transfer barrier of Zn2+ at the electrode/electrolyte interface, facilitating the uniform deposition of Zn2+ and suppressing water-caused side reactions. Consequently, the Zn||Zn symmetric cell assembled with CD-MWCNT shows a significantly enhanced cycling durability, maintaining a cycling life exceeding 1000 h even under a high current density of 5 mA cm-2. Furthermore, the full battery equipped with a V2O5 cathode displays an unparalleled long life. This work unveils a promising avenue toward the achievement of high-performance Zn metal anodes.
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The challenge of constructing a mechanically robust yet lightweight artificial solid-electrolyte interphase layer on lithium (Li) anodes highlights a trade-off between high battery safety and high energy density. Inspired by the intricate microstructure of the white sea urchin, we first develop a polyvinyl fluoride-hexafluoropropylene (PVDF-HFP) interfacial layer with a triple periodic minimal surface structure (TPMS) that could offer maximal modulus with minimal weight. This design endows high mechanical strength to an ordered porous structure, effectively reduces local current density, polarization, and internal resistance, and stabilizes the anode interface. At a low N/P ratio of ~3, using LiFePO4 as the cathode, Li anodes protected by TPMS-structured PVDF-HFP achieve an extremely low capacity-fading-rate of approximately 0.002 % per cycle over 200 cycles at 1â C, with an average discharge capacity of 142â mAh g-1. Meanwhile, the TPMS porous structure saves 50â wt % of the interfacial layer mass, thereby enhancing the energy density of the battery. The TPMS structure is conducive to large-scale additive manufacturing, which will provide a reference for the future development of lightweight, high-energy-density secondary batteries.
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Aqueous rechargeable zinc-based batteries (ZBBs) are emerging as desirable energy storage systems because of their high capacity, low cost, and inherent safety. However, the further application of ZBBs still faces many challenges, such as the issues of uncontrolled dendrite growth and severe parasitic reactions occurring at the Zn anode. Herein, an amino-grafted bacterial cellulose (NBC) film is prepared as artificial solid electrolyte interphase (SEI) for the Zn metal anodes, which can significantly reduce zinc nucleation overpotential and lead to the dendrite-free deposition of Zn metal along the (002) crystal plane more easily without any external stimulus. More importantly, the chelation between the modified amino groups and zinc ions can promote the formation of an ultra-even amorphous SEI upon cycling, reducing the activity of hydrate ions, and inhibiting the water-induced side reactions. As a result, the Zn||Zn symmetric cell with NBC film exhibits lower overpotential and higher cyclic stability. When coupled with the V2 O5 cathode, the practical pouch cell achieves superior electrochemical performance over 1000 cycles.
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Sodium (Na) metal is able to directly use as a battery anode but have a highly reductive ability of unavoidably occurring side reactions with organic electrolytes, resulting in interfacial instability as a primary factor in performance decay. Therefore, building stable Na metal anode is of utmost significance for both identifying the electrochemical performance of laboratory half-cells employed for quantifying samples and securing the success of room-temperature Na metal batteries. In this work, we propose an NaF-rich interface rapidly prepared by pressure and diglyme-induced defluorination reaction for stable Na metal anode. Once the electrolyte is dropped into the coin-type cells followed by a slight squeeze, the Na metal surface immediately forms a protective layer consisting of amorphous carbon and NaF, effectively inhibiting the dendrite growth and dead Na. The resultant Na metal anode exhibits a long-term cycling lifespan over 1800 h even under the area capacity of 3.0 mAh cm-2 . Furthermore, such a universal and facile method is readily applied in daily battery assembly regarding Na metal anode.
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In consideration of high specific capacity and low redox potential, lithium metal anodes have attracted extensive attention. However, the cycling performance of lithium metal batteries generally deteriorates significantly under the stringent conditions of high temperature due to inferior heat tolerance of the solid electrolyte interphase (SEI). Herein, controllable SEI nanostructures with excellent thermal stability are established by the (trifluoromethyl)trimethylsilane (TMSCF3 )-induced interface engineering. First, the TMSCF3 regulates the electrolyte decomposition, thus generating an SEI with a large amount of LiF, Li3 N, and Li2 S nanocrystals incorporated. More importantly, the uniform distributed nanocrystals have endowed the SEI with enhanced thermostability according to the density functional theory simulations. Particularly, the sub-angstrom visualization on SEI through a conventional transmission electron microscope (TEM) is realized for the first time and the enhanced tolerance to the heat damage originating from TEM imaging demonstrates the ultrahigh thermostability of SEI. As a result, the highly thermostable interphase facilitates a substantially prolonged lifespan of full cells at a high temperature of 70 °C. As such, this work might inspire the universal interphase design for high-energy alkali-metal-based batteries applicated in a high-temperature environment.
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The integration of ultrathin two-dimensional (2D) semiconductors with other conductive 2D materials to form hybrid electrocatalysts with abundant heterointerfaces can enhance the electrocatalytic activity by facilitating interfacial charge transfer. However, the hybrid electrocatalysts with weak interfacial bonding have limited effect on the electrocatalytic performance because the intrinsic activity of interfacial sites cannot be altered by weak interfacial interactions. As a proof-of-concept, we design ultrathin 2D-2D heterostructures with bridge-bonded Ni-O-Ti ligands based on single-layered Ti3C2TxMXene and metal hydroxides, and further reveal the structure-activity correlation between interfacial bonding and electrocatalytic oxygen evolution reaction by combining theoretical and experimental studies. Density functional theory calculations reveal the modulation of the electronic structure of interfacial metal sites after the formation of bridged interfacial Ni-O-Ti bonding. Compared with the hydrogen-bond-linked heterostructure, the ultrathin 2D-2D heterostructure with bridge-bonded Ni-O-Ti ligands shows enhanced intrinsic activity and stability towards electrocatalytic oxygen evolution with a very low overpotential of 205 mV at 10 mA cm-2and the long-term durability. This work provides a new understanding and approach for the design and development of 2D hybrid catalysts with highly efficient electrocatalytic activity.
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The proliferation of lithium (Li) dendrites stemming from uncontrollable Li deposition seriously limits the practical application of Li metal batteries. The regulation of uniform Li deposition is thus a prerequisite for promoting a stable Li metal anode. Herein, a commercial lithiophilic skeleton of soybean protein fiber (SPF) is introduced to homogenize the Li-ion flux and induce the biomimetic Li growth behavior. Especially, the SPF can promote the formation of a LiF-nanocrystal-enriched interface upon cycling, resulting in low interfacial impedance and rapid charge transfer kinetics. Finally, the SPF-mediated Li metal anode can achieve high Coulombic efficiency of 98.7% more than 550 cycles and a long-term lifespan over 3400 h (â¼8500 cycles) in symmetric tests. Furthermore, the practical pouch cell modified with SPF can maintain superior electrochemical performance over 170 cycles under a low N/P ratio and high mass loading of the cathode.
Assuntos
Fontes de Energia Elétrica , Lítio , Nanopartículas , Proteínas de Soja , Eletrodos , Lítio/química , Proteínas de Soja/químicaRESUMO
Sulfide electrolytes promise superior ion conduction in all-solid-state lithium (Li) metal batteries, while suffering harsh hurdles including interior dendrite growth and instability against Li and moist air. A prerequisite for solving such issues is to uncover the nature of the Li/sulfide interface. Herein, air-stable Li4SnS4 (LSS) as a prototypical sulfide electrolyte is selected to visualize the dynamic evolution and failure of the Li/sulfide interface by cryo-electron microscopy. The interfacial parasitic reaction (2Li + 2Li4SnS4 = 5Li2S + Sn2S3) is validated by direct detection of randomly distributed Li2S and Sn2S3 crystals. A bifunctional buffering layer is consequently introduced by self-diffusion of halide into LSS. Both the interface and the grain boundaries in LSS have been stabilized, eliminating the growing path of Li dendrites. The buffering layer enables the durability of Li symmetric cell (1500 h) and high-capacity retention of the LiFePO4 full-cell (95%). This work provides new insights into the hierarchical design of sulfide electrolytes.
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Lithium (Li)-metal batteries are one of the most promising candidates for the next-generation energy storage devices due to their ultrahigh theoretical capacity. The realistic development of a Li metal battery is greatly impeded by the uncontrollable dendrite proliferation upon the chemically active metallic Li. To visualize the micromorphology or even the atomic structure of Li deposits is undoubtedly crucial, while imaging the sensitive Li still faces a huge challenge technically.Cryogenic electron microscopy (cryo-EM), an emerging imagery technology renowned for structural elucidation of biomaterials, is offering increased possibilities for analyzing sensitive battery materials reaching subangstrom resolution. Particularly for revealing metallic Li, cryo-EM exhibits remarkable superiority compared with the conventional electron imaging technique. On the one hand, cryo-EM could prevent the low melting-point Li metal from being damaged by the high electron dose induced thermal effect. On the other hand, the extremely low temperature immensely retards the rate of the side reaction where the Li reacts with the atmosphere or water vapor before the vacuum state. Consequently, the cryo-EM could acquire a high-resolution image of electron-beam sensitive Li in its native state at the nano- or even atomic scale, thus benefiting the fundamental perception and rational design of Li metal anodes.Thus, in this Account, we aim to highlight the significance of cryo-EM in analyzing metallic Li and developing a high-performance Li metal battery. We focus on how highly resolved cryo-EM realizes the breakthrough in detecting the crucial evolution during battery cycling, e.g., lattice ordering of Li, nanostructures of the solid electrolyte interphase (SEI), nucleation sites, and interface between the solid electrolyte and the Li anode. First, we briefly summarize the progress of Li metal imaging by cryo-EM in a timed sequence. In particular, the recent studies from our group are classified in order to systematically delineate the advantages that cryo-transmission electron microscopy (cryo-TEM) addressed on understanding and developing the Li metal battery. Second, the efforts of exhibiting the long-range ordering Li lattice are described to cognize the crystal orientation of both Li dendrites and uniform spheres. Subsequently, the nanostructures of SEI detected by cryo-TEM, maybe the most key information during Li plating/stripping, are systematically summarized. Benefitting from the subangstrom visualization on the newly formed and the particular inactive SEI after long-term cycling, we emphasize cryo-TEM's guidance in designing a robust, highly Li+ conductive, and Li-restoration facilitated SEI. We then propose the strategy of introducing a nucleation-site to enable uniform Li deposition by showing the evidence of Li nucleation atomically monitored through cryo-TEM. Moreover, the series of the work of atomic imagery and corresponding optimization of the interfaces between the polymer-based solid electrolyte and the Li anode are concluded. Finally, critical perspectives about the further step of cryo-TEM in the realistic development of high-energy density battery systems are also succinctly reviewed.
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Silver nanowires are susceptible to degradation under ultraviolet (UV) light illumination. Encapsulating silver nanowire transparent conductive films (AgNW TCFs) with UV shielding materials usually result in the increasing of the sheet resistance or the decrease of the visible light transparency. Herein, we combine a reducing species (FeSO4) and a thin layer (overcoating) of UV shielding material to solve the stability and the optical performance issues simultaneously. The AgNW TCFs show excellent stability under continuous UV light illumination for 14 h, and their sheet resistance varies only 6%. The dramatic enhancement of the stability against UV light illumination for as-obtained TCFs will make them viable for real-world applications in touch panels and displays.
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The growth of Li dendrites hinders the practical application of lithium metal anodes (LMAs). In this work, a hollow nanostructure, based on hierarchical MoS2 coated hollow carbon particles preloaded with sulfur (C@MoS2 /S), was designed to modify the LMA. The C@MoS2 hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. More importantly, the encapsulated sulfur could gradually release lithium polysulfides during the Li plating/stripping, acting as an effective additive to promote the formation of a mosaic solid electrolyte interphase layer embedded with crystalline hybrid lithium-based components. These two factors together effectively suppress the growth of Li dendrites. The as-modified LMA shows a high Coulombic efficiency of 98 % over 500â cycles at the current density of 1â mA cm-2 . When matched with a LiFePO4 cathode, the assembled full cell displays a highly improved cycle life of 300â cycles, implying the feasibility of the proposed LMA.
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Structural flexibility can be a desirable trait of an operating catalyst because it adapts itself to a given catalytic process for enhanced activity. Here, amorphous cobalt hydroxide nanocages are demonstrated to be a promising electrocatalyst with an overpotential of 0.28 V at 10 mA cm-2 , far outperforming the crystalline counterparts and being in the top rank of the catalysts of their kind, under the condition of electrocatalytic oxygen evolution reaction. From the direct experimental in situ and ex situ results, this enhanced activity is attributed to its high structural flexibility in terms of 1) facile and holistic transformation into catalytic active phase; 2) hosting oxygen vacancies; and 3) structure self-regulation in a real-time process. Significantly, based on plausible catalytic mechanism and computational simulation results, it is disclosed how this structural flexibility facilitates the kinetics of oxygen evolution reaction. This work deepens the understanding of the structure-activity relationship of the Co-based catalysts in electrochemical catalysis, and it inspires more applications that require flexible structures enabled by such amorphous nanomaterials.
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Complex nanostructures with multi-components and intricate architectures hold great potential in developing high-performance electrode materials for lithium-ion batteries (LIBs). Herein, we demonstrate a facile self-templating strategy for the synthesis of metal vanadate nanomaterials with complex chemical composition of NiCo2 V2 O8 and a unique yolk-double shell structure. Starting with the Ni-Co glycerate spheres, NiCo2 V2 O8 yolk-double shell spheres are synthesized through an anion-exchange reaction of Ni-Co glycerate templates with VO3- ions, followed by an annealing treatment. By virtue of compositional and structural advantages, these NiCo2 V2 O8 yolk-double shell spheres manifest outstanding lithium storage properties when evaluated as anodes for LIBs. Impressively, an extra-high reversible capacity of 1228â mAh g-1 can be retained after 500 cycles at a high current density of 1.0â Ag-1 .
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Lithium-sulfur (Li-S) batteries, operated through the interconversion between sulfur and solid-state lithium sulfide, are regarded as next-generation energy storage systems. However, the sluggish kinetics of lithium sulfide deposition/dissolution, caused by its insoluble and insulated nature, hampers the practical use of Li-S batteries. Herein, leaf-like carbon scaffold (LCS) with the modification of Mo2C clusters (Mo2C@LCS) is reported as host material of sulfur powder. During cycles, the dissociative Mo ions at the Mo2C@LCS/electrolyte interface are detected to exhibit competitive binding energy with Li ions for lithium sulfide anions, which disrupts the deposition behavior of crystalline lithium sulfide and trends a shift in the configuration of lithium sulfide toward an amorphous structure. Combining the related electrochemical study and first-principle calculation, it is revealed that the formation of amorphous lithium sulfides shows significantly improved kinetics for lithium sulfide deposition and decomposition. As a result, the obtained Mo2C@LCS/S cathode shows an ultralow capacity decay rate of 0.015% per cycle at a high mass loading of 9.5 mg cm-2 after 700 cycles. More strikingly, an ultrahigh sulfur loading of 61.2 mg cm-2 can also be achieved. This work defines an efficacious strategy to advance the commercialization of Mo2C@LCS host for Li-S batteries.
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Recently emerging lithium ternary chlorides have attracted increasing attention for solid-state electrolytes (SSEs) due to their favorable combination between ionic conductivity and electrochemical stability. However, a noticeable discrepancy in Li-ion conductivity persists between chloride SSEs and organic liquid electrolytes, underscoring the need for designing novel chloride SSEs with enhanced Li-ion conductivity. Herein, an intriguing trigonal structure (i.e., Li3SmCl6 with space group P3112) is identified using the global structure searching method in conjunction with first-principles calculations, and its potential for SSEs is systematically evaluated. Importantly, the structure of Li3SmCl6 exhibits a high ionic conductivity of 15.46 mS cm-1 at room temperature due to the 3D lithium percolation framework distinct from previous proposals, associated with the unique in-plane cation ordering and stacking sequences. Furthermore, it is unveiled that Li3SmCl6 possesses a wide electrochemical window of 0.73-4.30 V vs Li+/Li and excellent chemical interface stability with high-voltage cathodes. Several other Li3MCl6 (M = Er, and In) materials with isomorphic structures to Li3SmCl6 are also found to be potential chloride SSEs, suggesting the broader applicability of this structure. This work reveals a new class of ternary chloride SSEs and sheds light on strategy for structure searching in the design of high-performance SSEs.
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Modifying the interface between the lithium metal anode (LMA) and the electrolyte is crucial for achieving high-performance lithium metal batteries (LMBs). Recent research indicates that altering Li-metal interfaces with polymer coatings is an effective approach to extend LMBs' cycling lifespan. However, the physical properties of these polymer-Li interfaces have not yet been fully investigated. Therefore, the structural stability, electronic conductivity, and ionic conductivity of polymer-Li interfaces were examined based on first-principles calculations in this study. Several representative polymer compounds utilized in LMBs were assessed, including polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyethylene oxide (PEO). Our research revealed that lithium fluoride is formed upon fluoropolymer degradation, explaining previously observed experimental results. Polymers containing nitrile groups exhibit strong adhesion to lithium metal, facilitating the formation of the stable interface layer. Regarding electronic conductivity, the fluoropolymers preserve a good insulating property, which diminished marginally in the presence of lithium, but that of PAN and PEO significantly reduces. Additionally, lithium diffusion on PTFE and PEO demonstrates low diffusion barriers and high coefficients, enabling easy transportation. Overall, our investigation reveals that the interfaces formed between various polymers and LMA have distinct characteristics, providing new fundamental insights for designing composites with tailored interface properties.
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The pursuit of high energy density in lithium batteries has driven the development of efficient electrodes with low levels of inactive components. Herein, a facile approach involving the use of π-π stacked nigrosine@carbon nanotube nanocomposites as an all-in-one additive for a LiFePO4 cathode has been developed. This design significantly reduces the proportion of inactive substances within the cathode, resulting in a battery that exhibits a high specific capacity of 143 mAh g-1 at a 1 C rate and shows commendable cyclic performance. Furthermore, the elimination of rigid current collectors endows the electrode with flexibility, offering avenues for future wearable energy storage devices.
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Hybrid materials with a rational organic-inorganic configuration can offer multifunctionality and superior properties. This principle is crucial but challenging to be applied in designing the solid electrolyte interphase (SEI) on lithium metal anodes (LMAs), as it substantially affects Li+ transport from the electrolyte to the anode. Here, an artificial SEI with an ultrahigh fluorine content (as high as 70.12 wt %) can be successfully constructed on the LMA using a high-voltage electrosynthesis strategy. This SEI consists of ultrafine lithium fluoride nanocrystals embedded in a fluorinated organic matrix, exhibiting excellent passivation and mechanical strength. Notably, the organic-inorganic interface demonstrates a high dielectric constant that enables fast Li+ transport throughout the SEI. Consequently, LMA coated with this SEI substantially enhances the cyclability of both half-cells and full cells, even under rigorous conditions. This work demonstrates the potential of rationally designed hybrid materials via a unique electrosynthetic approach for advanced electrochemical systems.
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Designing a general route for rational synthesis of a series or families of nanomaterials for emerging applications has become more and more fascinating and vital in the view of nanoscience and nanotechnology. Herein, we explore a general strategy for fabricating uniform nanocages of metal hydroxides (MHs) and metal oxides (MOs). A template-assisted route inspired by Pearson's hard and soft acid-base (HSAB) principle was employed for synthesizing MH nanocages via meticulous selection of the coordinating etchant as well as optimization of the reaction conditions. The concept of "coordinating etching" is successfully achieved in this work. This unique route shows potential in designing well-defined and high-quality MH nanocages with varying components, shell thicknesses, shapes, and sizes at room temperature. Consequently, porous MO nanocages can be obtained readily just through appropriate thermal treament of the respective MH nanocages. The overall strategy present in this work extends the application of the HSAB principle in nanoscience and offers a unqiue clue for rational fabrication of hollow (porous) and/or amorphous structures on the nanoscale, where these nanocages may present promising potential for various applications.
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Inspired by Pearson's hard and soft acid-base (HSAB) principle, uniform amorphous Ni(OH)2 nanoboxes with intact shell structures and various sizes are quickly fabricated by deliberately selecting S2O3(2-) as the coordinating etchant toward Cu2O templates and optimizing the reaction conditions. It is found that not only the solvent system but also the employing of a surfactant is vital for the fabrication of the nanoboxes. Ni(OH)2 nanoboxes, as an example, demonstrate an improved electrochemical sensing ability for glucose, which might be due to their amorphous and hollow structural features.