Modification Of Solid Electrolyte Interphase Research Articles

Visualizing and Regulating Dynamic Evolution of Interfacial Electrolyte Configuration during De‐solvation Process on Lithium‐Metal Anode

AbstractActing as a passive protective layer, solid‐electrolyte interphase (SEI) plays a crucial role in maintaining the stability of the Li‐metal anode. Derived from the reductive decomposition of electrolytes (e.g., anion and solvent), the SEI construction presents as an interfacial process accompanied by the dynamic de‐solvation process during Li‐metal plating. However, typical electrolyte engineering and related SEI modification strategies always ignore the dynamic evolution of electrolyte configuration at the Li/electrolyte interface, which essentially determines the SEI architecture. Herein, by employing advanced electrochemical in situ FT‐IR and MRI technologies, we directly visualize the dynamic variations of solvation environments involving Li+‐solvent/anion. Remarkably, a weakened Li+‐solvent interaction and anion‐lean interfacial electrolyte configuration have been synchronously revealed, which is difficult for the fabrication of anion‐derived SEI layer. Moreover, as a simple electrochemical regulation strategy, pulse protocol was introduced to effectively restore the interfacial anion concentration, resulting in an enhanced LiF‐rich SEI layer and improved Li‐metal plating/stripping reversibility.

Visualizing and Regulating Dynamic Evolution of Interfacial Electrolyte Configuration during De-solvation Process on Lithium-Metal Anode.

Acting as a passive protective layer, solid-electrolyte interphase (SEI) plays a crucial role in maintaining the stability of the Li-metal anode. Derived from the reductive decomposition of electrolytes (e.g., anion and solvent), the SEI construction presents as an interfacial process accompanied by the dynamic de-solvation process during Li-metal plating. However, typical electrolyte engineering and related SEI modification strategies always ignore the dynamic evolution of electrolyte configuration at the Li/electrolyte interface, which essentially determines the SEI architecture. Herein, by employing advanced electrochemical in situ FT-IR and MRI technologies, we directly visualize the dynamic variations of solvation environments involving Li+-solvent/anion. Remarkably, a weakened Li+-solvent interaction and anion-lean interfacial electrolyte configuration have been synchronously revealed, which is difficult for the fabrication of anion-derived SEI layer. Moreover, as a simple electrochemical regulation strategy, pulse protocol was introduced to effectively restore the interfacial anion concentration, resulting in an enhanced LiF-rich SEI layer and improved Li-metal plating/stripping reversibility.

Progress on Designing Artificial Solid Electrolyte Interphases for Dendrite-Free Sodium Metal Anodes

Nature-abundant sodium metal is regarded as ideal anode material for advanced batteries due to its high specific capacity of 1166 mAh g−1 and low redox potential of −2.71 V. However, the uncontrollable dendritic Na formation and low coulombic efficiency remain major obstacles to its application. Notably, the unstable and inhomogeneous solid electrolyte interphase (SEI) is recognized to be the root cause. As the SEI layer plays a critical role in regulating uniform Na deposition and improving cycling stability, SEI modification, especially artificial SEI modification, has been extensively investigated recently. In this regard, we discuss the advances in artificial interface engineering from the aspects of inorganic, organic and hybrid inorganic/organic protective layers. We also highlight key prospects for further investigations.

Interfacial Issues and Modification of Solid Electrolyte Interphase for Li Metal Anode in Liquid and Solid Electrolytes

AbstractThe high energy density required for the next generation of lithium batteries will likely be enabled by a shift toward lithium metal anode from the conventional intercalation‐based anode such as graphite. However, several critical challenges for Li metal originate from its highly reactive nature and the hostless reaction of deposition and stripping impede the practical use of Li metal as an anode. The role of the solid electrolyte interphase (SEI) is very important for the Li metal anode where the SEI must protect the dynamically changing surface of the Li metal. Since the SEI‐generating reaction mechanisms for the two different electrolyte systems, liquid and solid, are considerably different, the SEI layers formed between the Li metal and the electrolytes in the two electrolyte systems have substantially different properties, causing different interfacial issues. Inhibition of the interfacial problems requires different strategies to reinforce the SEI layer for each of the electrolyte systems. However, the differences in the two electrolyte systems have not been clearly compared in the prior literature. In this report, the interfacial issues for the two different electrolyte systems are compared and different strategies for SEI modification are provided to overcome the issues.

Interface Engineering with Nonsacrificial Perfluorinated-Anion Additives for Boosting the Kinetics of Lithium-Ion Batteries.

Though lithium-ion batteries (LIBs) have seen a meteoric rise in worldwide deployment over the last decade, they should be further advanced in constant demand of higher rate capability and wider temperature adaptability. A solid electrolyte interphase (SEI) is the essential part of LIBs, determining the charge-discharge performance and degradation behavior. Herein, improvement of the SEI properties is achieved by regulating the electrochemical double layer structure with a nonsacrificial electrolyte additive, that is, lithium nonafluoro-1-butanesulfonate. The anion adsorption of the additive affects the decomposition behavior of other additive and solvent species, and the generated SEI at the graphite electrode becomes thinner and more uniform, leading to decreased impedance and finally resulting in improved energy efficiency, power capability, and fast charging performance of the graphite/NCM811 cell. Furthermore, the low-temperature cycleability at -20 °C is considerably enhanced with no dendritic Li metal deposition at the negative electrode surface. A mechanistic study on the interfacial phenomena and the effect is carried out by using various theoretical and experimental methods, such as density functional theory calculations, electrochemical quartz crystal microbalance, and transmission electron microscopy. Consequently, the approach of SEI modification with the nonsacrificial electrolyte additive can be one of the effective ways to advance LIB technology in future.

Advances in functional organic material-based interfacial engineering on metal anodes for rechargeable secondary batteries.

Metal anodes with the merits of high theoretical capacity and low electrochemical potential are promising candidates for the construction of high-energy-density rechargeable secondary batteries. However, metal anodes with high chemical reactivity are likely to react with traditional liquid electrolytes, leading to the growth of dendrites, side reactions, and even safety issues. In this case, metal plating/stripping electrochemistry is associated with an enhanced ion transfer rate and homogeneous ion distribution on the metal surface. Herein, functional organic material (FOM)-based interfacial engineering on metal anodes is systematically presented, focusing on the effects of forming uniform solid electrolyte interphase (SEI) layer, homogenizing ion flux, accelerating ion transport, etc. This main content addresses the advances of FOMs in terms of SEI modification, 3D skeleton construction, and gel/solid-state electrolytes in multiple metal batteries, providing in-depth insights into the exploration of high-performance metal batteries. Moreover, other applications and outlooks for FOMs are further summarized, paying potential ways for the practical applications of FOM-based rechargeable secondary batteries.

Three-dimensional SEI framework induced by ion regulation in toroidal magnetic field for lithium metal battery

Lithium metal batteries are considered to have great potential as rechargeable batteries in next-generation energy storage devices. However, the generation of dead lithium and lithium dendrites caused by the rupture of the solid-electrolyte interphase (SEI) during cycling limits the application of lithium metal batteries. While tremendous efforts have been devoted to modification of SEI, the long-term and stable use of residual SEI has rarely been studied. Herein, we design a LiF-rich three-dimensional SEI framework (3DSF) formed in a toroidal magnetic field. This 3DSF can induce the uniform bottom-up deposition of lithium metal in the channel structure and realize 1,300 cycles at a high current density of 50 mA/cm2. The capacity of the battery paired with a high mass-loading LiFePO4 cathode (18.3 mg/cm2) maintains 98.2% at 1 C after 150 cycles. This work provides a simple and practical strategy for the additive free development of lithium metal battery technology.

Modification of solid electrolyte interphase on deposited lithium metal by large separation between the electrodes in ether-based electrolytes

Modification of solid electrolyte interphase on deposited lithium metal by large separation between the electrodes in ether-based electrolytes

Eliminating Graphite Exfoliation with an Artificial Solid Electrolyte Interphase for Stable Lithium-Ion Batteries.

Although graphite materials with desirable comprehensive properties dominate the anode market of commercial lithium-ion batteries (LIBs), their low capacity during fast charging precludes further commercialization. In the present work, natural graphite (G) is reported not only to suffer from low capacity during fast charging, but also from charge failure after many charging cycles. Using different characterization techniques, severe graphite exfoliation, and continuously increasing solid electrolyte interphase (SEI) are demonstrated as reasons for the failure of G samples. An ultrathin artificial SEI is proposed, addressing these problems effectively and ensuring extremely stable operation of the graphite anode, with a capacity retention of ≈97.5% after 400 cycles at 1 C. Such an artificial SEI modification strategy provides a universal approach to tailoring and designing better anode materials for next-generation LIBs with high energy densities.

Leveraging Cation Identity to Engineer Solid Electrolyte Interphases for Rechargeable Lithium Metal Anodes

Summary Engineering the solid electrolyte interphase (SEI) is a promising approach to improving Li metal battery performance. Recent work has shown that alkali metal additives can lead to smooth Li deposits, yet the underlying mechanisms are not understood. In this work, we demonstrate that alkali metal additives (here, K+) alter SEI composition, thickness, and solubility. Through post-mortem elemental analyses, we find that K+ ions do not deposit, but instead modify the reactivity of the electrode-electrolyte interface. Using quantitative nuclear magnetic resonance (NMR) and density functional theory (DFT), we show that K+ mitigates solvent decomposition at the Li metal surface. These findings suggest that alkali metal additives can be leveraged to suppress the formation of undesired SEI components (e.g., Li2CO3, soluble organic species), serving as an alternative approach for SEI modification compared to sacrificial additives. We believe that our work will spur further interest in the underexplored area of cation engineering.

Progress and Perspective of Constructing Solid Electrolyte Interphase on Stable Lithium Metal Anode

Lithium metal is considered as one of the most promising anode materials for high-energy-density rechargeable batteries. However, uncontrolled dendrite growth, the unstable interface between lithium metal anode and electrolyte, and infinite volume change are major obstacles in their practical applications. Constructing a solid electrolyte interphase (SEI) with high strength, good stability and desirable flexibility is one of the most promising approaches to mitigate the volume expansion of lithium anode and induce the uniform deposition of lithium for dendrite-free anode. Herein, we summarize the advances of SEI modification from the aspects of in-situ (adding electrolyte additives) and ex-situ (constructing artificial SEI) methods. The ideal SEI on lithium anode can effectively suppress the lithium dendrite growth and volume change of lithium metal anode. In the future study, the modification of SEI should focus on the suppression of side reactions between active lithium metal and electrolyte and the formation of dead lithium, which is quite significant to reduce the consumption of active lithium anode and electrolyte for safe and long-life high energy lithium metal batteries. Constructing an excellent SEI is a robust strategy to achieve the highly stable lithium metal anode for practical application of lithium metal batteries.

A Review of Solid Electrolyte Interphases on Lithium Metal Anode.

Lithium metal batteries (LMBs) are among the most promising candidates of high‐energy‐density devices for advanced energy storage. However, the growth of dendrites greatly hinders the practical applications of LMBs in portable electronics and electric vehicles. Constructing stable and efficient solid electrolyte interphase (SEI) is among the most effective strategies to inhibit the dendrite growth and thus to achieve a superior cycling performance. In this review, the mechanisms of SEI formation and models of SEI structure are briefly summarized. The analysis methods to probe the surface chemistry, surface morphology, electrochemical property, dynamic characteristics of SEI layer are emphasized. The critical factors affecting the SEI formation, such as electrolyte component, temperature, current density, are comprehensively debated. The efficient methods to modify SEI layer with the introduction of new electrolyte system and additives, ex‐situ‐formed protective layer, as well as electrode design, are summarized. Although these works afford new insights into SEI research, robust and precise routes for SEI modification with well‐designed structure, as well as understanding of the connection between structure and electrochemical performance, is still inadequate. A multidisciplinary approach is highly required to enable the formation of robust SEI for highly efficient energy storage systems.

Vinylene carbonate–LiNO3: A hybrid additive in carbonic ester electrolytes for SEI modification on Li metal anode

A hybrid solid electrolyte interphase (SEI) formation additive, vinylene carbonate (VC)–LiNO3, was investigated in carbonic ester electrolytes. An efficiency of lithium plating/stripping as high as nearly 100% and spherical Li deposits were obtained. The electrochemical impedance spectroscopy (EIS) results demonstrate that the modified SEI is very stable and of good conductivity. X-ray photoelectron spectroscopy (XPS) results indicate that VC–LiNO3 dominates the surface chemistry of the Li anode. The formation of Li3N in the SEI contributes to the enhancement of the anode performance.

Effect of VC additive on MFA-based electrolyte in Li-ion batteries

Rapid capacity fading of a graphite electrode was obtained with LiPF6/MFA electrolyte due to poor properties of solid electrolyte interphase (SEI). Vinylene carbonate (VC) was therefore applied to the MFA-based electrolyte as an SEI modification additive. The effects of VC concentration on the electrochemical properties of the graphite/Li half-cell were investigated at 25 and 60 °C. At 25 °C, the graphite electrode in MFA + 1% VC-based electrolyte showed good capacity retention of 300 mA h g−1 after 50 cycles, which was comparable with that in EC–DMC-based electrolyte; at 60 °C, the electrode in MFA + 3% VC-based electrolyte showed capacity retention of 240 mA h g−1 after 50 cycles, which was much better than that in EC–DMC-based electrolyte. Overabundant VC additives showed negative effects because of the formation of too-thick and/or too-dense SEI. DSC measurements were carried out to study the thermal behavior of MFA-based electrolyte coexisting with lithiated graphite. VC-containing MFA-based electrolyte still showed much better thermal stability than EC–DMC-based electrolyte. TG–MS analysis was performed on delithiated graphite cycled in MFA-based electrolyte containing different VC concentrations to analyze VC's effect on SEI formation. In summary, VC-added MFA-based electrolyte was a promising electrolyte for the development of safer Li-ion batteries, especially at elevated temperature.

Modification of Solid Electrolyte Interphase by Using Electrolytic Additives for Silicon Anode

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