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Silicon (Si)-based anodes offer high theoretical capacity for lithium-ion batteries but suffer from severe volume changes and continuous solid electrolyte interphase (SEI) degradation. Here, we address these challenges by selective methylation of 1,3-dioxolane (DOL), thus shifting the unstable bulk polymerization to controlled interfacial reactions and resulting in a highly elastic SEI. Comparative studies of 2-methyl-1,3-dioxolane (2MDOL) and 4-methyl-1,3-dioxolane (4MDOL) reveal that 4MDOL, with its larger ring strain and more stable radical intermediates due to hyperconjugation effect, promotes the formation of high-molecular-weight polymeric species at the electrode-electrolyte interface. This elastic, polymer-rich SEI effectively accommodates volume changes of Si and inhibits continuous side reactions. Our designed electrolyte enables Si-based anode to achieve 85.4% capacity retention after 400 cycles at 0.5 C without additives, significantly outperforming conventional carbonate-based electrolytes. Full cells also demonstrate stable long-term cycling. This work provides new insights into molecular-level electrolyte design for high-performance Si anodes, offering a promising pathway toward next-generation lithium-ion batteries with enhanced energy density and longevity.
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Lithium (Li) metal batteries hold significant promise in elevating energy density, yet their performance at ultralow temperatures remains constrained by sluggish charge transport kinetics and the formation of unstable interphases. In conventional electrolyte systems, lithium ions are tightly locked in the solvation structure, thereby engendering difficulty in the desolvation process and further exacerbating solvent decomposition. Herein, we propose a new push-pull electrolyte design strategy, utilizing molecular electrostatic potential (ESP) screening to identify 2,2-difluoroethyl trifluoromethanesulfonate (DTF) as an optimal cosolvent. Importantly, DTF exhibits a moderate ESP minimum (-21.0 kcal mol-1) to strike a balance between overly strong and overly weak Li ion affinity, which allows the sulfonyl group to effectively pull Li ions without disrupting the anion-rich solvation structure. Simultaneously, the difluoromethyl group, with a high ESP maximum (37.3 kcal mol-1), pushes solvent molecules via competitive hydrogen bonding. This design reconstructs existing solvation structures and expedites Li ion desolvation. Furthermore, fluorinated DTF demonstrates excellent stability at elevated voltage and facilitates the formation of robust inorganic-rich interphases. Impressively, rapid charge transfer kinetics can be achieved employing designed electrolyte, and the LiNi0.8Mn0.1Co0.1O2 (NMC811)||Li cells demonstrate excellent charge-discharge cycling stability with a high capacity exceeding 153 mAh g-1 even at -40 °C, retaining over 93% of initial capacity after 100 cycles under a 4.8 V charging cutoff. This work provides insights into the design of low-temperature electrolytes with a wide electrochemical window, advancing the development of batteries for extreme conditions.
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Ru-based electrocatalysts hold great promise for developing affordable proton exchange membrane (PEM) electrolyzers. However, the harsh acidic oxidative environment of the acidic oxygen evolution reaction (OER) often causes undesirable overoxidation of Ru active sites and subsequent serious activity loss. Here, we present an ultrathin and conformal depletion layer attached to the Schottky heterojunction of core/shell RuCo/RuCoOx that not only maximizes the availability of active sites but also improves its durability and intrinsic activity for acidic OER. Operando synchrotron characterizations combined with theoretical calculations elucidate that the lattice strain and charge transfer induced by Schottky heterojunction substantially regulate the electronic structures of active sites, which modulates the OER pathway and suppresses the overoxidation of Ru species. Significantly, the closed core/shell architecture of the RuCo/RuCoOx ensures the structure integrity of the Schottky heterojunction under acidic OER conditions. As a result, the core/shell RuCo/RuCoOx Schottky heterojunction exhibits an unprecedented durability up to 250 0 h at 10 mA cm-2 with an ultralow overpotential of â¼170 mV at 10 mA cm-2 in 0.5 M H2SO4. The RuCo/RuCoOx catalyst also demonstrates superior durability in a proton exchange membrane (PEM) electrolyzer, showcasing the potential for practical applications.
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High-voltage Li metal batteries (LMBs) based on ether electrolytes hold potential for achieving high energy densities exceeding 500 Wh kg-1, but face challenges with electrolyte oxidative stability, particularly concerning aluminum (Al) current collector corrosion. However, the specific chemistry behind Al corrosion and its effect on electrolyte components remains unexplored. Here, our study delves into Al corrosion in the representative LiFSI-DME electrolyte system, revealing that low-concentration electrolytes exacerbate Al current collector corrosion and solvent decomposition. In contrast, high-concentration electrolytes mitigate these issues, enhancing long-term stability. Remarkably, LiFSI-0.7DME electrolyte demonstrates exceptional stability with up to 1000 cycles at high voltage without significant capacity decay. These findings offer crucial insights into Al corrosion mechanisms in ether-based electrolytes, advancing our comprehension of high-voltage LMBs and facilitating their development for practical applications.
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Metallene is considered as an emerging family of electrocatalysts due to its atomically layered structure and unique surface stress. Here we propose a strategy to modulate the Bader charge transfer (BCT) between Pd surface and oxygenated intermediates via p-d electronic interaction by introducing single-atom p-block metal (M=In, Sn, Pb, Bi) into Pd metallene nanosheets towards efficient oxygen reduction reaction (ORR). X-ray absorption and photoelectron spectroscopy suggests that doping p-block metals could facilitate electron transfer to Pd sites and thus downshift the d-band center of Pd and weaken the adsorption energy of O intermediates. Among them, the developed Bi-Pd metallene shows extraordinarily high ORR mass activity of 11.34â A mgPd -1 and 0.86â A mgPd -1 at 0.9â V and 0.95â V in alkaline solution, respectively, representing the best Pd-based ORR electrocatalysts ever reported. In the cathode of a Zinc-air battery, Bi-Pd metallene could achieve an open-circuit voltage of 1.546â V and keep stable for 760â h at 10â mA cm-2. Theoretical calculations suggest that the BCT between Pd surface and *OO intermediates greatly affects the bond length between them (dPd-*OO) and Bi doping could appropriately reduce the amount of BCT and stretch the dPd-*OO, thus enhancing the ORR activity.
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The development of low-temperature lithium metal batteries (LMBs) encounters significant challenges because of severe dendritic lithium growth during the charging/discharging processes. To date, the precise origin of lithium dendrite formation still remains elusive due to the intricate interplay between the highly reactive lithium metal anode and organic electrolytes. Herein, we unveil the critical role of interfacial defluorination kinetics of localized high-concentration electrolytes (LHCEs) in regulating lithium dendrite formation, thereby determining the performance of low-temperature LMBs. We investigate the impact of solvation structures of LHCEs on low-temperature LMBs by employing tetrahydrofuran (THF) and 2-methyltetrahydrofuran (2-MeTHF) as comparative solvents. The combination of comprehensive characterizations and theoretical simulations reveals that the THF-based LHCE featured with a strong solvation strength exhibits fast interfacial defluorination reaction kinetics, thus leading to the formation of an amorphous and inorganic-rich solid-electrolyte interphase (SEI) that can effectively suppress the growth of lithium dendrites. As a result, the highly reversible Li metal anode achieves an exceptional Coulombic efficiency (CE) of up to â¼99.63% at a low temperature of -30 °C, thereby enabling stable cycling of low-temperature LMB full cells. These findings underscore the crucial role of electrolyte interfacial reaction kinetics in shaping SEI formation and provide valuable insights into the fundamental understanding of electrolyte chemistry in LMBs.
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Lithium (Li) metal batteries (LMBs) are the "holy grail" in the energy storage field due to their high energy density (theoretically >500â Wh kg-1 ). Recently, tremendous efforts have been made to promote the research & development (R&D) of pouch-type LMBs toward practical application. This article aims to provide a comprehensive and in-depth review of recent progress on pouch-type LMBs from full cell aspect, and to offer insights to guide its future development. It will review pouch-type LMBs using both liquid and solid-state electrolytes, and cover topics related to both Li and cathode (including LiNix Coy Mn1-x-y O2 , S and O2 ) as both electrodes impact the battery performance. The key performance criteria of pouch-type LMBs and their relationship in between are introduced first, then the major challenges facing the development of pouch-type LMBs are discussed in detail, especially those severely aggravated in pouch cells compared with coin cells. Subsequently, the recent progress on mechanistic understandings of the degradation of pouch-type LMBs is summarized, followed with the practical strategies that have been utilized to address these issues and to improve the key performance criteria of pouch-type LMBs. In the end, it provides perspectives on advancing the R&Ds of pouch-type LMBs towards their application in practice.
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Solid electrolytes (SEs) are central components that enable high-performance, all-solid-state lithium batteries (ASSLBs). Amorphous SEs hold great potential for ASSLBs because their grain-boundary-free characteristics facilitate intact solid-solid contact and uniform Li-ion conduction for high-performance cathodes. However, amorphous oxide SEs with limited ionic conductivities and glassy sulfide SEs with narrow electrochemical windows cannot sustain high-nickel cathodes. Herein, we report a class of amorphous Li-Ta-Cl-based chloride SEs possessing high Li-ion conductivity (up to 7.16 mS cm-1) and low Young's modulus (approximately 3 GPa) to enable excellent Li-ion conduction and intact physical contact among rigid components in ASSLBs. We reveal that the amorphous Li-Ta-Cl matrix is composed of LiCl43-, LiCl54-, LiCl65- polyhedra, and TaCl6- octahedra via machine-learning simulation, solid-state 7Li nuclear magnetic resonance, and X-ray absorption analysis. Attractively, our amorphous chloride SEs exhibit excellent compatibility with high-nickel cathodes. We demonstrate that ASSLBs comprising amorphous chloride SEs and high-nickel single-crystal cathodes (LiNi0.88Co0.07Mn0.05O2) exhibit â¼99% capacity retention after 800 cycles at â¼3 C under 1 mA h cm-2 and â¼80% capacity retention after 75 cycles at 0.2 C under a high areal capacity of 5 mA h cm-2. Most importantly, a stable operation of up to 9800 cycles with a capacity retention of â¼77% at a high rate of 3.4 C can be achieved in a freezing environment of -10 °C. Our amorphous chloride SEs will pave the way to realize high-performance high-nickel cathodes for high-energy-density ASSLBs.
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Ether-based electrolytes are considered as an ideal electrolyte system for sodium metal batteries (SMBs) due to their superior compatibility with the sodium metal anode (SMA). However, the selection principle of ether solvents and the impact on solid electrolyte interphase formation are still unclear. Herein, we systematically compare the chain ether-based electrolyte and understand the relationship between the solvation structure and the interphasial properties. The linear ether solvent molecules with different terminal group lengths demonstrate remarkably distinct solvation effects, thus leading to different electrochemical performance as well as deposition morphologies for SMBs. Computational calculations and comprehensive characterizations indicate that the terminal group length significantly regulates the electrolyte solvation structure and consequently influences the interfacial reaction mechanism of electrolytes on SMA. Cryogenic electron microscopy clearly reveals the difference in solid electrolyte interphase in various ether-based electrolytes. As a result, the 1,2-diethoxyethane-based electrolyte enables a high Coulombic efficiency of 99.9 %, which also realizes the stable cycling of Na||Na3 V2 (PO4 )3 full cell with a mass loading of ≈9â mg cm-2 over 500â cycles.
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The stable cycling of Mg-metal anodes is limited by several problems, including sluggish electrochemical kinetics and passivation at the Mg surface. In this study, we present a high-entropy electrolyte composed of lithium triflate (LiOTf) and trimethyl phosphate (TMP) co-added to magnesium bis(trifluoromethane sulfonyl)imide (Mg(TFSI)2 /1,2-dimethoxyethane (DME) to significantly improve the electrochemical performance of Mg-metal anodes. The as-formed high-entropy Mg2+ -2DME-OTf- -Li+ -DME-TMP solvation structure effectively reduced the Mg2+ -DME interaction in comparison with that observed in traditional Mg(TFSI)2 /DME electrolytes, thereby preventing the formation of insulating components on the Mg-metal anode and promoting its electrochemical kinetics and cycling stability. Comprehensive characterization revealed that the high-entropy solvation structure brought OTf- and TMP to the surface of the Mg-metal anode and promoted the formation of a Mg3 (PO4 )2 -rich interfacial layer, which is beneficial for enhancing Mg2+ conductivity. Consequently, the Mg-metal anode achieved excellent reversibility with a high Coulombic efficiency of 98 % and low voltage hysteresis. This study provides new insights into the design of electrolytes for Mg-metal batteries.
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The electrolyte solvation structure and the solid-electrolyte interphase (SEI) formation are critical to dictate the morphology of lithium deposition in organic electrolytes. However, the link between the electrolyte solvation structure and SEI composition and its implications on lithium morphology evolution are poorly understood. Herein, we use a single-salt and single-solvent model electrolyte system to systematically study the correlation between the electrolyte solvation structure, SEI formation process and lithium deposition morphology. The mechanism of lithium deposition is thoroughly investigated using cryo-electron microscopy characterizations and computational simulations. It is observed that, in the high concentration electrolytes, concentrated Li+ and anion-dominated solvation structure initiate the uniform Li nucleation kinetically and favor the decomposition of anions rather than solvents, resulting in inorganic-rich amorphous SEI with high interface energy, which thermodynamically facilitates the formation of granular Li. On the contrary, solvent-dominated solvation structure in the low concentration electrolytes tends to exacerbate the solvolysis process, forming organic-rich mosaic SEI with low interface energy, which leads to aggregated whisker-like nucleation and growth. These results are helpful to tackle the long-standing question on the origin of lithium dendrite formation and guide the rational design of high-performance electrolytes for advanced lithium metal batteries.
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Producing hydrogen via electrochemical water splitting with minimum environmental harm can help resolve the energy crisis in a sustainable way. Here, this work fabricates the pure nickel nanopyramid arrays (NNAs) with dense high-index crystalline steps as the cata electrode via a screw dislocation-dominated growth kinetic for long-term durable and large current density hydrogen evolution reaction. Such a monolithic NNAs electrode offers an ultralow overpotential of 469 mV at a current density of 5000 mA cm-2 in 1.0 m KOH electrolyte and shows a high stability up to 7000 h at a current density of 1000 mA cm-2 , which outperforms the reported catas and even the commercial platinum cata for long-term services under high current densities. Its unique structure can substantially stabilize the high-density surface crystalline steps on the catalytic electrode, which significantly elevates the catalytic activity and durability of nickel in an alkaline medium. In a typical commercial hydrogen gas generator, the total energy conversion rate of NNAs reaches 84.5% of that of a commercial Pt/Ti cata during a 60-day test of hydrogen production. This work approach can provide insights into the development of industry-compatible long-term durable, and high-performance non-noble metal catas for various applications.
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Hydrogen evolution reaction (HER) plays a key role in electrochemical water splitting, which is a sustainable way for hydrogen production. The kinetics of HER is sluggish in neutral media that requires noble metal catalysts to alleviate energy consumption during the HER process. Here, we present a catalyst comprising a ruthenium single atom (Ru1) and nanoparticle (Run) loaded on the nitrogen-doped carbon substrate (Ru1-Run/CN), which exhibits excellent activity and superior durability for neutral HER. Benefiting from the synergistic effect between single atoms and nanoparticles in the Ru1-Run/CN, the catalyst exhibits a very low overpotential down to 32 mV at a current density of 10 mA cm-2 while maintaining excellent stability up to 700 h at a current density of 20 mA cm-2 during the long-term test. Computational calculations reveal that, in the Ru1-Run/CN catalyst, the existence of Ru nanoparticles affects the interactions between Ru single-atom sites and reactants and thus improves the catalytic activity of HER. This work highlights the ensemble effect of electrocatalysts for HER and could shed light on the rational design of efficient catalysts for other multistep electrochemical reactions.
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Unstable cathode-electrolyte and/or anode-electrolyte interface in polymer-based sodium-ion batteries (SIBs) will deteriorate their cycle performance. Herein, a unique solvated double-layer quasi-solid polymer electrolyte (SDL-QSPE) with high Na+ ion conductivity is designed to simultaneously improve stability on both cathode and anode sides. Different functional fillers are solvated with plasticizers to improve Na+ conductivity and thermal stability. The SDL-QSPE is laminated by cathode- and anode-facing polymer electrolyte to meet the independent interfacial requirements of the two electrodes. The interfacial evolution is elucidated by theoretical calculations and 3D X-ray microtomography analysis. The Na0.67 Mn2/3 Ni1/3 O2 |SDL-QSPE|Na batteries exhibit 80.4â mAh g-1 after 400â cycles at 1â C with the Coulombic efficiency close to 100 %, which significantly outperforms those batteries using the monolayer-structured QSPE.
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Sodium metal batteries (SMBs) have been widely studied owing to their relatively high energy density and abundant resources. However, they still need systematic improvement to fulfill the harsh operating conditions for their commercialization. In this review, we summarize the recent progress in SMBs in terms of sodium anode modification, electrolyte exploration, and cathode design. Firstly, we give an overview of the current challenges facing Na metal anodes and the corresponding solutions. Then, the traditional liquid electrolytes and the prospective solid electrolytes for SMBs are summarized. In addition, insertion- and conversion-type cathode materials are introduced. Finally, an outlook for the future of practical SMBs is provided.
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Uniform and compact Zn deposition-dissolution is essential to achieve high Coulombic efficiency and long lifespan for Zn anodes. More attention has been commonly focused on the suppression of macroscopic Zn dendrites in the previous reports. The rational control of the microstructure of Zn deposition to prevent the intrinsic volume expansion and pulverization of Zn metal so as to stabilize Zn anodes is less discussed. Herein, we construct a three-dimensional topological Zn deposition at the nanoscale through an in situ electrochemical process in the optimal hybrid aqueous electrolyte. The topological electrode structure can efficiently accommodate microscopic strain and volume variation and thus largely preserve the macroscopic integrity and electrical contact of Zn anodes, leading to enhanced reversibility and stability. With the unique topological structure of Zn deposition, the Coulombic efficiency of Zn anodes could reach >99.9% with excellent cycling over 1182 h at 2 mA cm-2 and 2 mA h cm-2 (Zn utilization: 11.4%). The evolution of "dead" Zn during repeated cycling is first investigated using a homemade semiquantitative analysis method to determine the critical "short slab" for aqueous Zn batteries under the practical application. This work provides an insightful method to regulate the microscopic morphology of Zn deposition for high-performance Zn batteries.
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Significant challenges remain in developing rechargeable zinc batteries mainly because of reversibility problems on zinc-metal anodes. The dendritic growth and hydrogen evolution on zinc electrodes are major obstacles to overcome in developing practical and safe zinc batteries. Here, a dendrite-free and hydrogen-free Zn-metal anode with high Coulombic efficiency up to 99.6% over 300 cycles is realized in a newly designed nonaqueous electrolyte, which comprises an inexpensive zinc salt, zinc acetate, and a green low-cost solvent, dimethyl sulfoxide. Surface transformation on Cu substrate plays a critical role in facilitating the dendrite-free deposition process, which lowers the diffusion energy barrier of the Zn atoms, leading to a uniform and compact thin film for zinc plating. Furthermore, in situ electrochemical atomic force microscopy reveals the plating process via a layer-by-layer growth mechanism and the stripping process through an edge-dissolution mechanism. In addition, Zn||Mo6 S8 full cells exhibit excellent electrochemical performance in terms of cycling stability and rate capability. This work presents a new opportunity to develop nonaqueous rechargeable zinc batteries.
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There remain significant challenges in developing fast-charging materials for lithium-ion batteries (LIBs) due to sluggish ion diffusion kinetics and unfavorable electrolyte mass transportation in battery electrodes. In this work, a mesoporous single-crystalline lithium titanate (MSC-LTO) microrod that can realize exceptional fast charge/discharge performance and excellent long-term stability in LIBs is reported. The MSC-LTO microrods are featured with a single-crystalline structure and interconnected pores inside the entire single-crystalline body. These features not only shorten the lithium-ion diffusion distance but also allow for the penetration of electrolytes into the single-crystalline interior during battery cycling. Hence, the MSC-LTO microrods exhibit unprecedentedly high rate capability, achieving a specific discharge capacity of ≈174 mAh g-1 at 10 C, which is very close to its theoretical capacity, and ≈169 mAh g-1 at 50 C. More importantly, the porous single-crystalline microrods greatly mitigate the structure degradation during a long-term cycling test, offering ≈92% of the initial capacity after 10 000 cycles at 20 C. This work presents a novel strategy to engineer porous single-crystalline materials and paves a new venue for developing fast-charging materials for LIBs.
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Single-atom catalysts (SACs) have attracted tremendous research interests in various energy-related fields because of their high activity, selectivity and 100% atom utilization. However, it is still a challenge to enhance the intrinsic and specific activity of SACs. Herein, we present an approach to fabricate a high surface distribution density of iridium (Ir) SAC on nickel-iron sulfide nanosheet arrays substrate (Ir1/NFS), which delivers a high water oxidation activity. The Ir1/NFS catalyst offers a low overpotential of ~170 mV at a current density of 10 mA cm-2 and a high turnover frequency of 9.85 s-1 at an overpotential of 300 mV in 1.0 M KOH solution. At the same time, the Ir1/NFS catalyst exhibits a high stability performance, reaching a lifespan up to 350 hours at a current density of 100 mA cm-2. First-principles calculations reveal that the electronic structures of Ir atoms are significantly regulated by the sulfide substrate, endowing an energetically favorable reaction pathway. This work represents a promising strategy to fabricate high surface distribution density single-atom catalysts with high activity and durability for electrochemical water splitting.