Stable Solid Electrolyte Interphase Research Articles

Recent Progress of Advanced Functional Separators in Lithium Metal Batteries.

As a representative in the post-lithium-ion batteries (LIBs) landscape, lithium metal batteries (LMBs) exhibit high-energy densities but suffer from low coulombic efficiencies and short cycling lifetimes due to dendrite formation and complex side reactions. Separator modification holds the most promise in overcoming these challenges because it utilizes the original elements of LMBs. In this review, separators designed to address critical issues in LMBs that are fatal to their destiny according to the target electrodes are focused on. On the lithium anode side, functional separators reduce dendrite propagation with a conductive lithiophilic layer and a uniform Li-ion channel or form a stable solid electrolyte interphase layer through the continuous release of active agents. The classification of functional separators solving the degradation stemming from the cathodes, which has often been overlooked, is summarized. Structural deterioration and the resulting leakage from cathode materials are suppressed by acidic impurity scavenging, transition metal ion capture, and polysulfide shuttle effect inhibition from functional separators. Furthermore, flame-retardant separators for preventing LMB safety issues and multifunctional separators are discussed. Further expansion of functional separators can be effectively utilized in other types of batteries, indicating that intensive and extensive research on functional separators is expected to continue in LIBs.

High ionic conducting lithium fluoride rich solid electrolyte interphase induced by polysulfide for carbon-based dual ion batteries

Carbon-based dual ion batteries (DIBs) promise a high working voltage, ease of production, low cost and low environmental impact, yet they suffer from poor electrochemical performances ascribed predominantly to electrolyte decomposition, consequently impacting the stability of solid electrolyte interphase (SEI) formation in the negative electrode. Herein, we report a facile pre-formation of lithium fluoride (LiF)-rich SEI derived from lithium polysulfide (LiPS) added lithium bis(trifluoromethane)sulfonimide (LiTFSI)-based electrolyte. A pre-formed lithium sulfide (Li2S) as the inner passivation layer effectively facilitates the growth of LiF on carbon anode, which greatly enhances the ionic conductivity of SEI and prevents the formation of Li dendrites. The designed electrolyte consisting of 3.4 M LiTFSI in the mixture of ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) (1:1 by vol.) with the addition of 0.1 M LiPS achieves excellent compatibility with activated carbon, delivered an initial specific capacity of 408 mAh g−1 with coulombic efficiency ∼100% at 1 A g−1 over 150 cycles. With an in-depth analysis of compositions and the distribution of decomposition products at the interface, the critical impact of Li2S on SEI formation is revealed. DIB full cells assembled using the carbon anodes with a pre-formed SEI layer delivered an initial discharge capacity of 57.2 mAh g−1 and average voltage of 4.35 V. The above-mentioned findings shed new light on SEI pre-forming technique for high-performance DIB based on the rational design of electrolytes.

Stoichiometric Ti3C2Tx Coating for Inhibiting Dendrite Growth in Anode‐Free Lithium Metal Batteries

Lithium metal batteries (LMBs) and anode‐free LMBs (AFLMBs) present a solution to the need for batteries with a significantly superior theoretical energy density. However, their adoption is hindered by low Coulombic efficiency (CE) and rapid capacity fading, primarily due to the formation of unstable solid electrolyte interphase (SEI) layer and Li dendrite growth as a result of uneven Li plating. Here, we report on the use of a stoichiometric Ti3C2Tx (S‐Ti3C2Tx) MXene coating on the copper current collector to enhance the cyclic stability of an anode‐free lithium metal battery. The S‐Ti3C2Tx coating provides abundant nucleation sites, thereby lowering the overpotential for Li nucleation, and promoting uniform Li plating. Additionally, the fluorine (−F) termination of S‐Ti3C2Tx participates in the SEI formation, producing a LiF‐rich SEI layer, vital for stabilizing the SEI and improving cycle life. Batteries equipped with S‐Ti3C2Tx@Cu current collectors displayed reduced Li consumption during stable SEI formation, resulting in a significant decrease in capacity loss. AFLMBs with S‐Ti3C2Tx@Cu current collectors achieved a high initial capacity density of 4.2 mAh cm−2, 70.9% capacity retention after 50 cycles, and an average CE of 98.19% in 100 cycles. This innovative application of MXenes in the energy field offers a promising strategy to enhance the performance of AFLMBs and could potentially accelerate their commercial adoption.

Correlation between surface/bulk properties and electrochemical cycling performance of pure silicon anode materials

State-of-the-art lithium-ion batteries (LIBs) employ silicon (Si)-graphite composite anode with just a few percentages of Si active material, whose cycle-life relies on a stable solid electrolyte interphase (SEI) layer. As a number of various types of industrial Si active materials are currently available, an informative guideline based on the material properties and resultant cycling performance of different pure Si (i.e., without graphite) anode materials is strongly needed for material selection. The present study provides for the first time the correlation among material's surface and bulk properties, the SEI formation behavior, and cycling behavior of highly loaded pure Si anodes (2.3 mAh cm−2) prepared from four different industrial active materials, which are SiOx, carbon-coated Si, and bare Si with submicron and micron sizes. Commercial electrolyte with 10 wt% fluoroethylene carbonate additive is used for electrochemical performance evaluation. Based on solid-state NMR, XPS, and electrochemical analysis results, SiOx is determined to be relatively beneficial for practical applications beyond Si materials, in the aspects of high structural and particle morphology stability, cycling stability and suppressed interfacial resistance. This is mainly because of more effective accommodation of volume change of Si and oxygen-enriched surface (SEI) stability. The data give insight into the rational design of well-working Si-dominant or pure Si anodes for high energy density LIBs.

Unraveling the incompatibility mechanism of ethylene carbonate-based electrolytes in sodium metal anodes

Ethylene carbonate (EC) is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity, relatively stable solid electrolyte interphase (SEI), and wide electrochemical window. EC is also the most widely used electrolyte solvent in sodium ion batteries. However, compared to lithium metal, sodium metal (Na) shows higher activity and reacts violently with EC-based electrolyte (NaPF6 as solute), which leads to the failure of sodium metal batteries (SMBs). Herein, we reveal the electrochemical instability mechanism of EC on sodium metal battery, and find that the combination of EC and NaPF6 is electrically reduced in sodium metal anode during charging, resulting in the reduction of the first coulombic efficiency, and the continuous consumption of electrolyte leads to the cell failure. To address the above issues, an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes. Specifically, ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) as solvents and fluoroethylene carbonate (FEC) as SEI-forming additive have been identified as the optimal solvent for NaFP6 based electrolyte and used in Na4Fe3(PO4)2(P2O7)||Na batteries. The batteries exhibit excellent capacity retention rate of about 80% over 1000 cycles at a cut-off voltage of 4.3 V.

Enabling Uniform and Stable Lithium-Ion Diffusion at the Ultrathin Artificial Solid-Electrolyte Interface in Siloxene Anodes.

Constructing a stable and robust solid electrolyte interphase (SEI) has a decisive influence on the charge/discharge kinetics of lithium-ion batteries (LIBs), especially for silicon-based anodes which generate repeated destruction and regeneration of unstable SEI films. Herein, a facile way is proposed to fabricate an artificial SEI layer composed of lithiophilic chitosan on the surface of two-dimensional siloxene, which has aroused wide attention as an advanced anode for LIBs due to its special characteristics. The optimized chitosan-modified siloxene anode exhibits an excellent reversible cyclic stability of about 672.6 mAh g-1 at a current density of 1000mA g-1 after 200 cycles and 139.9 mAh g-1 at 6000mA g-1 for 1200 cycles. Further investigation shows that a stable and LiF-rich SEI film is formed and can effectively adhere to the surface during cycling, redistribute lithium-ion flux, and enable a relatively homogenous lithium-ion diffusion. This work provides constructive guidance for interface engineering strategy of nano-structured silicon anodes.

High-Safety Electrolytes with an Anion-Rich Solvation Structure Tuned by Difluorinated Cations for High-Voltage Lithium Metal Batteries.

As next-generation energy storage devices, lithium metal batteries (LMBs) must offer high safety, high-voltage resistance, and a long life span. Electrolyte engineering is a facile strategy to tailor the interfacial chemistry of LMBs. In particular, the solvation structure and derived solid electrolyte interphase (SEI) are crucial for a satisfactory battery performance. Herein, a novel middle-concentrated ionic liquid electrolyte (MCILE) with an anion-rich solvation structure tuned by difluorinated cations is demonstrated to achieve ultrahigh safety, high-voltage stability, and excellent ternary-cathode compatibility. Novel gem-difluorinated cations first synthesized for prestoring fluorine on positively charged species, not only preferentially adsorb in the inner-Helmholtz layers, but also participate in regulating the Li+ solvation structure, resulting in a robust interphase. Moreover, these weak interactions in the Li+ solvation structure including anion-solvent and ionic liquid (IL) cation-solvent pairs are first revealed, which are beneficial for promoting an anion-dominated solvation structure and the desolvation process. Benefiting from the unique anion-rich solvation structure, a stable hetero-SEI structure is obtained. The designed MCILE exhibits compatibility with Li metal anode and the high-voltage ternary cathode at high temperatures (60°C). This work provides a new approach for regulating the solvation structure and electrode interphase chemistry of LMBs via difluorinated IL cations.

Enhancing low-temperature electrolyte performance through intermittent discharge for improved LiODFB additive film formation

The challenge of improving low-temperature performance in lithium-ion batteries (LIBs) is attributed to the formation of an unstable solid electrolyte interphase (SEI) film. Lithium difluoro(oxalate)borate (LiODFB) has demonstrated potential in enhancing capacity retention and reducing impedance at low temperatures by establishing a high ion conductivity and stable SEI layer. Previous research indicates that the BOF2− anion, a soluble product of film formation additive of LiODFB hinder salt decomposition by aggregating on the electrode surface. This study presents a strategy to intensify the film formation process of LiODFB additives by introducing an optimal standing time during intermittent discharge processes. Three specific stages of soluble product diffusion are discussed. Diffusion starts from the outer layer of adsorption composed of soluble substances, gradually extends to the inner layer of adsorption, and finally establishes a new connection with the electrode. A brief standing time proves insufficient for inner adsorption layer diffusion, while excessively extended standing time fails to accelerate LiODFB decomposition. A standing time of 2300 s is selected to promote a stable SEI layer. This strategy elevates the capacity retention rate of cells at –20 °C from 66.59 % to 84.44 %. The study offers a method to address battery performance degradation in low-temperature conditions.

Design Principles of Mediation Layer for Current Collectors Toward High‐Performance Anode‐Free Potassium‐Metal Batteries: A Case Study of Cu6Sn5 on Copper

AbstractAnode‐free potassium (K) metal batteries are promising candidates in high‐energy‐density batteries. Nevertheless, the notorious potassium dendrite growth and poor K plating/stripping efficiency originating from the potassiophobicity of conventional Cu current collectors impede their practical applications. Herein, by means of systematically multi‐scale theoretical simulations, the correlations among K deposition morphology, nucleation sites, and potassiophilicity of mediation layers are well illuminated from thermodynamics and dynamics perspectives. As a proof of concept, a potassiophilic alloy Cu6Sn5 layer is constructed on commercial Cu foils via a facile electroless plating approach. The designed Cu6Sn5@Cu can guide the homogeneous distribution of K+ flux and regulate the electronic field, promoting uniform K+ plating and stripping. Meanwhile, a KF‐rich solid electrolyte interphase (SEI) layer with high mechanical strength is electrochemically induced and formed, facilitating the transport of K+ through SEI and enhancing the stability of SEI. Consequently, Cu6Sn5@Cu delivers great performance with durable stability of up to 600 h (1 mA cm−2 and 1 mAh cm−2) in no‐reservoir half‐cells. Benefiting from the unique mediation layer design, a novel anode‐free K‐metal full‐cell prototype demonstrates ameliorative cyclic stability. This work advances a fundamental understanding and establishes the bridge between the potassium deposition morphology and mediation layer properties for anode‐free potassium‐metal batteries.

Highly Stable Lithium Metal Batteries Enabled by Tuning the Molecular Polarity of Diluents in Localized High-Concentration Electrolytes.

Electrolyte plays a crucial role in ensuring stable operation of lithium metal batteries (LMBs). Localized high-concentration electrolytes (LHCEs) have the potential to form a robust solid-electrolyte interphase (SEI) and mitigate Li dendrite growth, making them a highly promising electrolyte option. However, the principles governing the selection of diluents, a crucial component in LHCE, have not been clearly determined, hampering the advancement of such a type of electrolyte systems. Herein, the diluents from the perspective of molecular polarity are rationally designed and developed. A moderately fluorinated solvent, 1-(1,1,2,2-tetrafluoroethoxy)propane (TNE), is employed as a diluent to create a novel LHCE. The unique molecular structure of TNE enhances the intrinsic dipole moment, thereby altering solvent interactions and the coordination environment of Li-ions in LHCE. The achieved solvation structure not only enhances the bulk properties of LHCE, but also facilitates the formation of more stable anion-derived SEIs featured with a higher proportion of inorganic species. Consequently, the corresponding full cells of both Li||LiFePO4 and Li||LiNi0.8Co0.1Mn0.1O2 cells utilizing Li thin-film anodes exhibit extended long-term stability with significantly improved average Coulombic efficiency. This work offers new insights into the functions of diluents in LHCEs and provides direction for further optimizing the LHCEs for LMBs.

MOF-Derived Bimetallic Selenide CoNiSe2 Nanododecahedrons Encapsulated in Porous Carbon Matrix as Advanced Anodes for Lithium-Ion Batteries.

Transition metal selenides have received considerable attention as promising candidates for lithium-ion battery (LIB) anode materials due to their high theoretical capacity and safety characteristics. However, their commercial viability is hampered by insufficient conductivity and volumetric fluctuations during cycling. To address these issues, we have utilized bimetallic metal-organic frameworks to fabricate CoNiSe2/C nanodecahedral composites with a high specific surface area, abundant pore structures, and a surface-coated layer of the carbon-based matrix. The optimized material, CoNiSe2/C-700, exhibited impressive Li+ storage performance with an initial discharge specific capacity of 2125.5 mA h g-1 at 0.1 A g-1 and a Coulombic efficiency of 98% over cycles. Even after 1000 cycles at 1.0 A g-1, a reversible discharge specific capacity of 549.9 mA h g-1 was achieved. The research highlights the synergistic effect of bimetallic selenides, well-defined nanodecahedral structures, stable carbon networks, and the formation of smaller particles during initial cycling, all of which contribute to improved electronic performance, reduced volume change, increased Li+ storage active sites, and shorter Li+ diffusion paths. In addition, the pseudocapacitance behavior contributes significantly to the high energy storage of Li+. These features facilitate rapid charge transfer and help maintain a stable solid-electrolyte interphase layer, which ultimately leads to an excellent electrochemical performance. This work provides a viable approach for fabricating bimetallic selenides as anode materials for high-performance LIBs through architectural engineering and compositional tailoring.

High-Rate SiO Lithium-Ion Battery Anode Enabled by Rationally Interfacial Hybrid Encapsulation Engineering.

The development of a high-rate SiO lithium-ion battery anode is seriously limited by its low intrinsic conductivity, sluggish interfacial charge transfer (ICT), and unstable dynamic interface. To tackle the above issues, interfacial encapsulation engineering for effectively regulating the interfacial reaction and thus realizing a stable solid electrolyte interphase is significantly important. Hybrid coating, which aims to enhance the coupled e-/Li+ transport via the employment of dual layers, has emerged as a promising strategy. Herein, we construct a hybrid MXene-graphene oxide (GO) coating layer on the SiO microparticles. In the design, Ti3C2Tx MXene acts as a "bridge", which forms a close covalent connection with SiO and GO through Ti-O-Si and Ti-O-C bonds, respectively, thus greatly reducing the ICT resistance. Moreover, the Ti3C2Tx with rich surface groups (e.g., -OH, -F) and GO outer layers with an intertwined porous framework synergistically enable the pseudocapacitance dominated behavior, which is beneficial for fast lithium-ion storage. Accordingly, the as-made Si@MXene@GO anode exhibits considerably reinforced lithium-ion storage performance in terms of superior rate performance (1175.9 mA h g-1 at 5 A g-1) and long cycling stability (1087.6 mA h g-1 capacity retained after 1000 cycles at 2.0 A g-1). In-depth interfacial chemical composition analysis further reveals that an inorganically rich interphase with a gradient distribution of LiF and Li2O formed at the electrolyte/anode interface ensures mechanical stability during repeated cycles. This work paves a feasible way for maximizing the potential of SiO anodes toward fast-charging lithium-ion batteries.

Borate-containing triblock copolymer electrolytes for improved lithium-ion transference number and interface stability

The electrolytes with high lithium-ion transference number (tLi+) can reduce the formation of concentration polarization during charge/discharge process and improve the electrochemical performance of lithium-ion batteries (LIBs). Herein, we report triblock copolymer electrolytes (PBOEE) containing borate. The sp2 hybridized boron atoms acting as Lewis acids can anchor the anions of lithium salts, enabling PBOEE to achieve high tLi+ of up to 0.53. Also, the borate groups can promote the formation of stable organic-rich solid electrolyte interphase (SEI) film, which enables the Li symmetric cell to cycle stably at 0.1 mA cm−2/0.1 mAh cm−2 for more than 3100 h with a low overpotential of 0.08 V under 50 °C. The optimized PBOEE_24 has an ionic conductivity of 1.41 × 10−4 S cm−1 and electrochemical stability window of 4.8 V vs. Li+/Li at 50 °C. Combining these advantages, the LiFePO4/PBOEE_24/Li cell exhibits an initial discharge specific capacity of 157.3 mA h g−1 at 0.5C with a capacity retention of 85 % after 600 cycles under 50 °C. At a higher current density of 1C, the discharge capacity maintains at 128.0 mA h g−1 after 400 cycles with a capacity retention of 84.88 %. These results suggest that block copolymer containing sp2 hybridized boron atoms is a promising all-solid-state polymer electrolyte.

Reliable Organic Carbonyl Electrode Materials Enabled by Electrolyte and Interfacial Chemistry Regulation.

ConspectusLithium-ion batteries (LIBs) have achieved great success and dominated the market of portable electronics and electric vehicles owing to their high energy density and long-term cyclability. However, if applying LIBs for large-scale energy storage scenarios, such as regulating the output of electricity generated by sustainable energy in the future age of carbon neutrality, the current electrochemistry of LIBs based on Li-ion interaction/deinteraction between a transition-metal oxide cathode and graphite anode will suffer from problems of scarce natural resources (e.g., Li, Co, and Ni) and high energy consumption/CO2 emission involved in the production of electrodes. Similarly, other commercial batteries such as lead-acid batteries and nickel-metal hydride batteries are also plagued by these issues.In contrast, organic electrode materials, especially carbonyl materials, exhibit advantages of abundant resources, renewability, high capacity, environmental friendliness, and structural designability and have shown great promise for various rechargeable batteries in recent years. However, organic carbonyl electrode materials generally exhibit unsatisfactory cycling stability and rate performance, which are highly dependent on the electrolyte and interfacial chemistry. Appropriate electrolytes and a stable electrode/electrolyte interface would be beneficial for preventing the dissolution of organic carbonyl electrode materials and/or their redox intermediates in electrolytes and promoting fast ion transport between the electrode and electrolyte. In this regard, designing an appropriate electrolyte and constructing a stable electrode/electrolyte interface are the keys to enhancing the comprehensive performance of organic carbonyl electrode materials.In this Account, on the basis of our progress and related works from other groups in the past decade, we afford an overview of understanding the effects of electrolyte and interfacial chemistry on the electrochemical performance of organic carbonyl electrode materials. We will start by briefly introducing the basic properties, working mechanisms, and issues of organic carbonyl electrode materials. Then, the implications of electrolyte and electrode/electrolyte interfacial chemistry on electrochemical performance will be summarized and highlighted through discussing the performance of organic carbonyl electrodes in different types of electrolytes (organic liquid and aqueous and solid-state electrolytes). Meanwhile, the design principles of electrolytes and interfacial chemistry for organic carbonyl electrodes are also discussed. A representative example is that organic carbonyl electrode materials often exhibit better electrochemical performance in ether-based electrolytes than in ester-based electrolytes, which could be mainly attributed to the stable and robust solid electrolyte interphase (SEI) formed on carbonyl electrodes in the ether-based electrolyte. This example demonstrates the importance of investigating the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials. Finally, future perspectives on designing appropriate electrolytes and understanding electrode/electrolyte interfacial chemistry will also be discussed. It is meaningful to thoroughly reveal the dynamic evolution of the electrode/electrolyte interface during discharge/charge processes and evaluate the compatibility between electrolytes and organic carbonyl electrode materials under practical conditions using limited quantities of electrolytes and high areal-specific-capacity electrodes in the future. This Account could attract more attention to electrolytes and the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials and finally promote their future commercial applications.

Facile Fabrication of Polymer Electrolytes with Branched Structure via Deep Eutectic Electrolyte-Enabled In Situ Polymerizations.

The demand for higher energy density in energy storage devices drives further research on lithium metal batteries (LMBs) because of the high theoretical capacity and low voltage of lithium metal anode. Polymer electrolytes (PEs) exhibit obvious advantages in combating volatilization and leakage compared with liquid electrolytes, which improves the safety of LMBs. However, it is still difficult to construct PEs with a stable electrolyte-electrode interface for high-performance and long-term life LMBs. Herein, the gel polymer electrolyte (GPE-SL) containing deep eutectic electrolyte (DEE) and branchlike polymer skeleton are designed and prepared by the DEE-induced in situ cationic and radical polymerizations. The DEE provides a smooth Li+ migration pathway to ensure the electrochemical properties, and the multibrominated polymer matrix formed in situ enables a LiBr-rich solid electrolyte interphase (SEI) layer on lithium metal anode and prolongs the life span of LMBs. Hence, the Li|GPE-SL|LiFePO4 battery displays an excellent cycling stability with 84% capacity retention after 1200 cycles at 1C. This simple deep eutectic electrolyte-induced polymerization method provides a promising direction for high-performance LMBs with improved anode-electrolyte compatibility through the construction of a stable SEI layer in situ.

Interfacial solvation-structure regulation for stable Li metal anode by a desolvation coating technique

Rechargeable lithium (Li) metal batteries face challenges in achieving stable cycling due to the instability of the solid electrolyte interphase (SEI). The Li-ion solvation structure and its desolvation process are crucial for the formation of a stable SEI on Li metal anodes and improving Li plating/stripping kinetics. This research introduces an interfacial desolvation coating technique to actively modulate the Li-ion solvation structure at the Li metal interface and regulate the participation of the electrolyte solvent in SEI formation. Through experimental investigations conducted using a carbonate electrolyte with limited compatibility to Li metal, the optimized desolvation coating layer, composed of 12-crown-4 ether-modified silica materials, selectively displaces strongly coordinating solvents while simultaneously enriching weakly coordinating fluorinated solvents at the Li metal/electrolyte interface. This selective desolvation and enrichment effect reduce solvent participation to SEI and thus facilitate the formation of a LiF-dominant SEI with greatly reduced organic species on the Li metal surface, as conclusively verified through various characterization techniques including XPS, quantitative NMR, operando NMR, cryo-TEM, EELS, and EDS. The interfacial desolvation coating technique enables excellent rate cycling stability (i.e., 1C) of the Li metal anode and prolonged cycling life of the Li||LiCoO2 pouch cell in the conventional carbonate electrolyte (E/C 2.6 g/Ah), with 80% capacity retention after 333 cycles.

Enhancing Zn‐Metal Anode Stability: Key Effects of Electrolyte Additives on Ion‐Shield‐Like Electrical Double Layer and Stable Solid Electrolyte Interphase

AbstractOwing to zinc dendrites and parasitic reactions, aqueous Zn‐metal batteries often suffer from poor reversibility and cyclability. Electrolyte additives present a promising strategy to improve Zn anode stability. However, the ever‐evolving perspectives and mechanisms, paradoxically, complicate battery design, causing a scenario where any electrolyte additive seems to be effective. Herein, it is taken ionic liquid (IL) additives as an example and detailed explored the impact of three typical IL anions, namely OTF−, TFA−, and BF4−. It is identified that the primary determinant of electrolyte additives as their electrical double layer (EDL) structures and their subsequent solid‐electrolyte interface (SEI) composition. An advantageous EDL structure, akin to an ion‐shield, can reduce the absorption of H2O molecules, which further enrich the SEI with zincophilic and hydrophobic components, thereby mitigating parasitic reactions and Zn dendrite formation. As a result, the Zn||Zn cell with optimal [EMIM]OTF additives demonstrates an exceptional cycling life under challenging conditions, its cumulative plated capacity surpasses most previously reported results by utilizing different IL additives. This work extends beyond performance enhancements, representing a valuable exploration of key criteria for electrolyte additives is believed. These insights are expected to offer fundamental guidance for future research and electrolyte design.

4,5-Difluoro-1,3-dioxolan-2-one as a film-forming additive improves the cycling and thermal stability of SiO/C anode Li-ion batteries

SiO/C is currently considered the most favorable anode material for high-energy-density lithium-ion batteries (LIBs). Nevertheless, its potential applications are constrained because of its inherent capacity decay and thermal safety concerns engendered by its volumetric expansion during extended cycling periods. The present study investigated the effectiveness of 4,5-difluoro-1,3-dioxolane-2-one (DFEC) as a film-forming additive to augment the safety and electrochemical efficacy of LIBs. A blank electrolyte (BE) was used as a control. Electrochemical test and characterization results revealed that the capacity retention rate of a battery containing the DFEC additive improved significantly; specifically, it increased from 45.23% (for a battery with the BE) to 73.14%. DFEC also increased the quantity of LiF components on the anode surface, resulting in the formation of a robust and stable solid electrolyte interphase film, which enhanced the battery’s cycling stability. Differential scanning calorimetry, thermogravimetric analysis, and thermokinetic analysis revealed that DFEC inhibited exothermic reactions between the electrolyte and the lithiated anode. Notably, the initial reaction temperature for the electrolyte slowly transitioned from 232.17 to 238.67 °C. The apparent activation energy increased from 439.56 to 506.995 kJ/mol. This study presents a practical approach for the development of safe, high-energy-density batteries by incorporating DFEC as a film-forming additive.

Electrodeposition preparation and electrochemical properties of silicon anode

The theoretical capacity of silicon is about 4200 mA h g−1, so the silicon anode is the most attractive substitute for the graphite anode of lithium-ion battery. In this paper, amorphous silicon thin films is successfully prepared on the surface of 12 µm thick copper foil by pulsed electrodeposition, then the silicon anode is prepared and the electrochemical performance is tested. The research results show that the silicon anode exhibits higher reversible capacity (1200 mA h g−1) compared with the graphite anode, and there is no obvious capacity fade after 100 cycles at the current density of 200 mA g−1. The amorphous silicon can alleviate the cracking of silicon thin films, and form stable Solid Electrolyte Interphase, which can reduce lithium consumption and improve the coulombic efficiency of lithium-ion battery. In addition, the lithium-ion battery with silicon anode exhibits excellent cycle performance and rate capability.

Refining the inner Helmholtz plane adsorption for achieving a stable solid-electrolyte interphase in reversible aqueous Zn-ion pouch cells

The reversibility and stability of aqueous Zn ion batteries (AZIBs) is extremely dependent on inner Helmholtz plane (IHP) structure and properties at the zinc anode/aqueous electrolyte interface. The hydrogen evolution reaction, corrosion, passivation, and uncontrolled growth of Zn dendrites all stem from the abundant presence of active H2O and irregular deposition of Zn within the IHP. In this study, we propose a strategy by using N, N'-Methylenebisacrylamide (MBA) as a bis-zincophilic site additive to effectively regulate molecular distribution within the IHP. This approach can prevent active H2O molecules from decomposing and suppress side reactions, while also can homogenize ion flux to obtain the uniform Zn deposition and stripping. Moreover, the adsorption of MBA onto IHP promotes the formation of a compact and homogeneous solid-electrolyte interphase (SEI). As a result, the utilization of an MBA/ZnSO4 electrolyte resulted in exceptional Coulombic efficiency of 99.7 % for up to 1300 cycles. The Zn//Zn symmetric pouch cell demonstrated an impressively high accumulated capacity exceeding 15,000 mA h. Furthermore, the Zn//NH4V4O10 zinc-ion pouch cell exhibited a capacity retention rate of 85 % after undergoing 1000 cycles at a current density of 1 A g−1. These results highlight the significant potential of incorporating MBA additive into practical applications.