Solid Electrolyte Interface Film Research Articles

Engineering the solid electrolyte interphase for enhancing high-rate cycling and temperature adaptability of lithium-ion batteries.

In overcoming the barrier of rapid Li+ transfer in lithium-ion batteries at extreme temperatures, the desolvation process and interfacial charge transport play critical roles. However, tuning the solvation structure and designing a kinetically stable electrode-electrolyte interface to achieve high-rate charging and discharging remain a challenge. Here, a lithium nonafluoro-1-butanesulfonate (NFSALi) additive is introduced to optimize stability and the robust solid electrolyte interface film (SEI), realizing a rapid Li+ transfer process and the structural integrity of electrode materials. The NFSALi-derived thinner, fluorine-rich, and sulfur-containing SEI in nitrile-assisted carbonate electrolytes effectively suppresses the decomposition of valeronitrile solvent during high-rate cycling and wide-temperature operation (-40-55 °C). More importantly, the graphite‖LiNi0.5Co0.2Mn0.3O2 pouch cell demonstrates a capacity retention of 66.88% after 200 high-rate cycles with 3C charging and 5C discharging under a high-temperature condition of 55 °C. This work provides significant guidance to develop inorganic-rich interfacial chemistry for lithium-ion batteries under extreme operating conditions.

Generation of solid electrolyte interface (SEI) film on graphite negative electrode surface in calcium-ion secondary batteries and its dependence on electrolyte

Generation of solid electrolyte interface (SEI) film on graphite negative electrode surface in calcium-ion secondary batteries and its dependence on electrolyte

Fabrication of CoSe2/FeSe2 heterostructures with stable solid electrolyte interface film and low surface activation energy for Na-ion batteries

The abundant availability and potential cost benefits of sodium-ion batteries (SIBs) have generated increasing interest as viable alternatives to lithium-ion batteries (LIBs). However, the development of SIBs is considerably hindered...

Advances in the application of silicon-based materials in anodes for lithium-ion batteries

Lithium-ion batteries (LIBs) are a vital energy storage technology being utilized increasingly in electric cars, portable electronics, energy storage systems, and other industries as the world focuses more on clean energy and sustainable development. Notwithstanding, the constraints associated with conventional graphite anode materials concerning energy density and cycle stability provide a challenge in fulfilling the forthcoming demand for high-performance batteries. Because silicon compounds offer a substantially greater theoretical specific capacity than conventional graphite anodes, they have gained popularity as research targets for anode materials for next-generation high-performance lithium-ion batteries. However, silicon materials still face many challenges in commercial applications. It has a low first-time coulombic efficiency, which increases the cost of the battery and reduces its actual usable capacity. Its solid electrolyte interface (SEI) film formed during charging and discharging is less stable, which can easily lead to battery performance degradation. To overcome the challenges of silicon materials in LIBs cell applications, this paper summarises the application of silicon nanostructures, silicon/carbon composites, and silicon/metal composites in LIBs. It aims to broaden its application in LIBs further.

2,2-Dimethylvinylboronic acid as an effective solid electrolyte interface formation additive for high performance sodium ion batteries

The main challenges brought by the unstable solid electrolyte interface (SEI) film seriously hinder the practical application of sodium ion batteries (SIBs). Herein, 2,2-dimethylvinylboronic acid (DEBA) is used as a film-forming electrolyte additive to improve the stability of the interface between the hard carbon (HC) and electrolyte for SIBs, naming the resulting electrode HCD-DEBA. DEBA is preferentially decomposed before the electrolyte and involved in forming SEI. Besides, in the cycling process, the C=C bonds in DEBA undergo the in-situ polymerization to construct the polymer skeleton of the SEI, inducing forming a thinner solid electrolyte interface layer with lower interface impedance, thus enhancing cycling stability. The optimized HCD-2%DEBA exhibits a first-cycle discharge specific capacity of 332.5 mAh g−1 at 0.1 C, while the HCD is 329.6 mAh g−1. HCD-2% DEBA was able to cycle 5000 times at a high rate of 5 C with capacities ranging from 195.7 mAh g−1 to 110.4 mAh g−1, however, the one without DEBA died after about 2000 cycles with an initial discharge capacity of 83.6 mAh g−1. This work provides a simple strategy for improving the cycle capacity of hard carbon half-cells and constructing the solid electrolyte interphase.

Carbon-Coated Coaxial Cable-like ZnO@SiO2@C for High-Performance Lithium-Ion Battery Anode Materials.

The practical applications of SiO2 anode material are limited by large volume changes and poor electronic conductivity. To reduce the effects of these problems, a carbon-coated coaxial cable-like ZnO@SiO2@C composite material was prepared. ZnO has a certian electronic conductivity and an electrochemical activity, and the carbon layer can alleviate the volume variation of SiO2, effectively improving the electronic conductivity and structural stability. At the same time, the carbon layer acts as a barrier to prevent direct contact between SiO2 and the electrolyte, thus promoting the formation of stable solid electrolyte interface films. Carbon-coated coaxial cable-like ZnO@SiO2@C exhibits excellent electrochemical properties, with a discharge specific capacity of 480.3 mAh g-1 after 500 cycles at a current density of 1 A g-1. The carbon-coated coaxial cable-like structure presents a potential application for alloying anode materials.

Fluorine-Doping Carbon-Modified Si/SiOx to Effectively Achieve High-Performance Anode.

To address the significant challenges encountered by silicon-based anodes in high-performance lithium-ion batteries (LIBs), including poor cycling stability, low initial coulombic efficiency (ICE), and insufficient interface compatibility, this work innovatively prepares high-performance Si/SiOx@F-C composites via in situ coating fluorine-doping carbon layer on Si/SiOx surface through high-temperature pyrolysis. The Si/SiOx@F-C electrodes exhibit superior LIB performance with a high ICE of 79%, exceeding the 71% and 43% demonstrated by Si/SiOx@C and Si/SiOx, respectively. These electrodes also show excellent rate performance, maintaining a capacity of 603 mAhg-1 even under a high current density of 5000 mAg-1. Notably, the Si/SiOx@F-C electrode sustains a high reversible capacity of 829 mAh g-1 at 1000mA g-1 over 1400 cycles, and 588 mAhg-1 at 3000 mAg-1 even over 2400 cycles, capacity retention of up to 82.12%. Comprehensive characterization and analysis of the fluorine-doped carbon layer reveal its role in enhancing electrical conductivity and preventing structural degradation of the material. The abundant fluorine in the coating layer significantly increases the LiF concentration in the solid electrolyte interface (SEI) film, improving interfacial compatibility and overall lithium storage performance. This method is both straightforward and effective, providing a promising blueprint for the broader application of Si-based anodes in advanced lithium batteries.

LiF-induced in-situ engineering of a dense inorganic SEI for superior lithium storage in black phosphorus anode

Black phosphorus (BP) has been highly regarded as a favourable candidate for fast-charging anode applications owing to its high theoretical capacity and advantageous charge–discharge platform. However, BP faces challenges related to compromised electrochemical performance resulting from an unstable solid-electrolyte interface (SEI) and substantial volumetric expansion. This study proposes the engineering of an inorganic-dense SEI on the surface of BP-C through the strategic incorporation of lithium fluoride (LiF). The presence of LiF in the system preferentially promotes LiPF6 adsorption from the electrolyte, facilitating the in-situ formation of a lithium-enriched inorganic SEI film on the BP-C particulate surfaces. This strategic formation effectively mitigates subsequent electrolytic decomposition, accommodates volumetric expansion, and substantially improves the rate capability and cycling stability of the system. Consequently, the BP-LiF-C electrode demonstrates high initial coulombic efficiency of 86.8 % and maintains a steady capacity of 926.1 mAh g−1 over 700 cycles at 2000 mA g−1. Moreover, when paired with a LiFePO4 cathode, the full cell exhibits long cycling stability, retaining 98.6 % of its capacity after 500 cycles at 2000 mA g−1, and performs at high rate. Therefore, utilising LiF to modulate the interfacial architecture of BP-based electrode composites provide notable guidance to enhance energy storage systems.

Enhancing Li+ Transportation at Graphite‐Low Concentration Electrolyte Interface Via Interphase Modulation of LiNO3 and Vinylene Carbonate

ABSTRACTThe solvent‐rich solvent sheath in low‐concentration electrolytes (LCEs) not only results in high desolvation energy of Li+, but also forms organic‐rich solid electrolyte interface film (SEI) with poor Li+ conductivity, which hinders Li+ transport at the electrode‐electrolyte interface and greatly limits the application of LCEs. Here, the electrochemical performance of the LCEs is enhanced by dual interfacial modification with LiNO3 and vinylene carbonate (VC) additives. Results show that LiNO3 is preferentially reduced at about 1.65 V to form an inorganic‐rich but incomplete SEI inner layer. The formation of Li3N and LiNxOy inorganic components helps to achieve rapid Li+ transport in the SEI film, and the bare electrode surface caused by the incomplete SEI inner layer provides a place for the subsequent decomposition of VC. Then, at a lower potential of about 0.73 V, VC is reduced to generate the poly(VC)‐rich SEI outer layer, which provides lithium‐philic sites and greatly weakens the interaction between Li+ and ethylene carbonate (EC). The interaction modulates the Li+ solvation structure at the interface and reduces the desolvation energy of Li+. This ingenious design of the bilayer SEI film greatly enhances Li+ transport and inhibits the decomposition of traditional carbonate solvents and the swelling of graphite. As a result, the electrochemical performance of the battery using 0.5 M LiPF6 EC/diethyl carbonate (DEC) + 0.012 M LiNO3 + 0.5 vt% VC is improved to a higher level than the one using 1.0 M LiPF6 EC/DEC electrolyte. This research expands the design strategy and promising applications of LCEs by constructing a favorable SEI to enhance Li+ transport at the electrode‐electrolyte interface.

Weakly solvated electrolyte enables the robust solid electrolyte interface on SiOx anodes for lithium-ion battery

Silicon oxide (SiOx) anodes are considered to be the promising alternative to graphite anodes for lithium-ion batteries. However, the traditional carbonate electrolyte fails to generate the effective solid electrolyte interface (SEI) on SiOx anodes to well adapt the large volume expansion of SiOx particles. Herein, a weakly solvated perfluorinated electrolyte with dual lithium salts was designed to match SiOx anodes. The perfluorinated solvent with weakened solvation ability and the strong coordination of Li+-DFOB− and Li+-TFSI− lead to an anion-dominated solvated shell, which induces the formation of inorganics-rich SEI. The high-strength bonds (Li-F, B-F, B-O, B-N et al.) enable high mechanical strength and rapid ion migration of the SEI film, thereby effectively accommodating the volume expansion of SiOx and avoiding continuous decomposition of the electrolyte. Furthermore, as designed electrolyte also shows excellent flame retardancy and high voltage stability. Consequently, the SiOx anode exhibits remarkably improved cycling performance in contrast to that in traditional carbonate electrolyte, maintaining 1073.7 mAh/g after 300 cycles at 1.0 A/g when paired with metal Li, and presents excellent compatibility with commercial cathodes including LiFePO4 and LiNi0.8Co0.1Mn0.1O2. This work provides a new inspiration and path for the design of electrolyte highly matched with silicon oxide anodes.

Manipulating Electrolyte Interface Chemistry Enables High-Performance TiO2 Anode for Sodium-Ion Batteries

Titanium dioxide (TiO2) has emerged as a candidate anode material for sodium-ion batteries (SIBs). However, their applications still face challenges of poor rate performance and low initial coulomb efficiency (ICE), which are induced by the unstable solid-electrolyte interface (SEI) and sluggish Na+ diffusion kinetics in conventional ester-based electrolytes. Herein, inspired by the electrode/electrolyte interfacial chemistry, tetrahydrofuran (THF) is exploited to construct an advanced electrolyte and reveal the relationship between the improved electrochemical performance and the derived SEI film on TiO2 anode. The robust and homogeneously distributed F-rich SEI film formed in THF electrolyte favors fast interfacial charge transfer dynamics and excellent interfacial stability. As a result, the THF electrolyte endows the TiO2 anode with greatly improved ICE (64.5%), exceptional rate capabilities (186 mAh g−1 at 5.0 A g−1), and remarkable cycling stability. This study elucidates the control of interfacial chemistry by rational electrolyte design and offers insights into the development of high-performance and long-lifetime TiO2 anode.

The effect of low-temperature starting on the thermal safety of lithium-ion batteries

With the widespread application of lithium-ion batteries (LIBs) in the field of energy equipment, their probability of starting or operating in low-temperature environments is also increasing. However, there is currently a lack of research on the changes in thermal safety of batteries after use in corresponding environments. In this work, the thermal safety performance, degradation mechanisms and evaluation method of LIBs at low-temperature start-up conditions are studied. The results show that starting at low temperature leads to the decrease of cell capacity. Electrochemical characterization and cell disassembly analysis indicate that the loss of active lithium ions is mainly caused by the evolution of lithium and the growth of solid electrolyte interface films. In addition, the low-temperature startup results in the decrease of thermal runaway (TR) onset temperature and the advance of TR time. In order to quantitatively evaluate the safety state of the LIBs, an evaluation model based on Informer algorithm is established. The model extracts the discharge capacity, discharge energy and dV/dQ as aging characteristic parameters, and extracts TR temperature as thermal safety characteristic parameters. The data set is processed by cubic spline interpolation. After training and verification, the accuracy of the model reaches 80 %.

Thermo-electric behavior analysis and coupled model characterization of 21,700 cylindrical ternary lithium batteries affected by cyclic aging

In order to achieve a balance between the precision of thermal behavior simulation of lithium batteries affected by cyclic aging and the practicality of engineering popularization and application, a simple degraded battery thermal model needs to be constructed. In this article, a characterization approach for the coupled battery thermo-electric model affected by cyclic aging is designed. This method is suitable for simulating the thermal behavior of lithium degraded batteries with different materials and shapes under different environmental temperatures. This paper introduces the idea by taking the 21,700 cylindrical ternary lithium batteries as an example. Firstly, based on the interaction mechanism between the growth of the solid electrolyte interface film on the battery negative electrode surface at the microscopic level and the battery thermoelectric coupling characteristics at the macro level, the paper constructs a theoretical model of the degraded battery. Further, it conducts experiments to analyze the battery charging and discharging behaviors in the process of cyclic aging. Based on experimental data, this paper conducts multiple fitting calculations to extract essential modeling parameters. Subsequently, this paper builds the battery physical model in the simulation software based on the above modeling parameters. It applies the battery physical model to simulate the thermal characteristics and temperature field. Then, it conducts experiments to demonstrate the precision of the model. This paper uses the infrared imaging technique to visualize and analyze temperature field variations on the battery surface. And it uses thermocouple temperature sensors to capture the battery surface temperature changes. The simulation results are compared with the experimental data, the errors are less than 5 %. Compared with other existing battery thermal models, the model of this paper is more suitable for engineering popularization and application of thermal behavior simulation of lithium batteries affected by cyclic aging.

Unraveling chemical origins of dendrite formation in zinc-ion batteries via in situ/operando X-ray spectroscopy and imaging

To prevent zinc (Zn) dendrite formation and improve electrochemical stability, it is essential to understand Zn dendrite growth, particularly in terms of morphology and relation with the solid electrolyte interface (SEI) film. In this study, we employ in-situ scanning transmission X-ray microscopy (STXM) and spectro-ptychography to monitor the morphology evolution of Zn dendrites and to identify their chemical composition and distribution on the Zn surface during the stripping/plating progress. Our findings reveal that in 50 mM ZnSO4, the initiation of moss/whisker dendrites is chemically controlled, while their continued growth over extended cycles is kinetically governed. The presence of a dense and stable SEI film is critical for inhibiting the formation and growth of Zn dendrites. By adding 50 mM lithium chloride (LiCl) as an electrolyte additive, we successfully construct a dense and stable SEI film composed of Li2S2O7 and Li2CO3, which significantly improves cycling performance. Moreover, the symmetric cell achieves a prolonged cycle life of up to 3900 h with the incorporation of 5% 12-crown-4 additives. This work offers a strategy for in-situ observation and analysis of Zn dendrite formation mechanisms and provides an effective approach for designing high-performance Zn-ion batteries.

Iron-decorated N/S co-doped porous carbon for sodium-ion battery anode to achieve high initial coulombic efficiency

Hard carbon materials are preferred as anode materials for sodium-ion batteries due to their abundance, low price, and environmental friendliness. However, doping-based modification usually induces low initial coulombic efficiency (ICE), which seriously affects the practical application of carbon materials. In this work, Fe-modified N/S co-doped porous carbon is prepared using the salt template method. Fe, N, and S are uniformly distributed on the porous carbon to form an interwoven network structure, providing abundant active sites. Moreover, during the electrochemical reaction, FeNx effectively catalyzes the generation of solid electrolyte interface (SEI) film, which reduces the consumption of Na+ in the side reaction, leading to a high initial coulombic efficiency, and at the same time, the stabilized SEI film accelerates the diffusion of electrons and ions, effectively enhancing the multiplication rate performance. The NFSC exhibits a high specific capacity (371.3 mAh/g) by the co-coordination strategy and a high ICE (85.9 %). This study provides new ideas for research based on the modification of carbon materials.

Degradation mechanism and assessment for different cathode based commercial pouch cells under different pressure boundary conditions

Lithium-ion pouch cell exhibits expansion behavior during cycling, which determines the overall performance and external pressure evolution. It is significant to reveal the impact of pressure boundary conditions on battery degradation. This study investigated the degradation mechanism of different cathode-based pouch cells (LiFePO4 (LFP) and Li(Ni0.6Co0.2Mn0.2)O2 (NCM622)) under four distinct pressure boundary conditions (I-II. clamping with two foam pads having varying compression force deflection (CFD) respectively, III. without foam pad, IV. unpressurized). One hundred of pre-experiment cycles determined the optimal external pressure (12.5 kPa) to slow down the degradation process. Subsequently, multi-cell paralleled cycling experiments were conducted for 1000 cycles. The capacity degradation of LFP and NCM cells with the optimal condition was 6.0 % and 12.6 % less than that of unpressurized cells. The electrochemical tests indicated that unpressurized cells had the fastest rate of lithium-ion loss, which is related to solid electrolyte interface (SEI) film growth and lithium plating. Post-mortem characterization analysis further revealed that the pressure boundary condition is crucial for the electrode morphology, pressure distribution, and gas generation, which affect battery degradation. The pressurized cells’ surface exhibited fewer instances of lithium plating. With the stiff foam clamped, pouch cell swelling can be absorbed while maintaining contact between cell components, resulting in fewer electrode folds and cracks. This study provides valuable insights for designing long-lifespan battery modules or packs.

Enhancing electric field intensity of interfacial electric double layer to improve properties of solid electrolyte interface for sodium-ion batteries

The electrical double layer (EDL) provides a critical area, where the specific adsorption on the electrode dominates the initial structure and chemical composition of the solid electrolyte interface (SEI) film. Therefore, the SEI can be optimized by adjusting the properties of the EDL. Here, we regulate the properties of EDL to optimize the composition and morphology of the SEI film on the hard carbon anode surface by adding NaF with small molecule structure. The preferential accumulation of NaF additives on the electrode surface enhances the electric field intensity and promotes electrolyte decomposition. That is, the formed SEI film rich in inorganic NaF and B-O components, can significantly improve the storage capacity of sodium ions in the hard carbon anode and accelerate the rapid transport of sodium ions. This strategy enables the cycling capacity to improve by 13.5 %, and maintain a stable capacity retention rate of 86.2 % at the rate of 1C after 500 cycles, thereby extending the lifespan and increasing the capacity of the rechargeable battery. The strategy that utilizing small molecule additives to enhance the electric field intensity of EDL provides a new approach to improve the performances of SEI film and battery performances.

Engineering Moderately Lithiophilic Paper-Based Current Collectors with Variable Solid Electrolyte Interface Films for Anode-Free Lithium Batteries.

Compared to traditional lithium metal batteries, anode-free lithium metal batteries use bare current collectors as an anode instead of Li metal, making them highly promising for mass production and achieving high-energy density. The current collector, as the sole component of the anode, is crucial in lithium deposition-stripping behavior and greatly impacts the rate of Li depletion from the cathode. In this study, to investigate the lithiophilicity effect of the current collector on the solid electrolyte interface (SEI) film construction and cycling performance of anode-free lithium batteries, various lightweight paper-based current collectors were prepared by electroless plating Cu and lipophilic Ag on low-dust paper (LDP). The areal densities of the as-prepared LDP@Cu, LDP@Cu-Ag, and LDP@Ag were approximately 0.33 mg cm-2. The use of lipophilic Ag-coated collectors with varying loadings allowed for the regulation of lipophilicity. The impacts of these collectors on the distribution of SEI components and Li depletion rate in common electrolytes were investigated. The findings suggest that higher loadings of lipophilic materials, such as Ag, on the current collector increase its lipophilicity but also lead to significant Li depletion during the cycling process in full-cell anode-free Li metal batteries. Thus, moderately lithiophilic current collectors, such as LDP@Cu-Ag, show more potential for Li deposition and striping and stable SEI with a low speed of Li depletion.

Electrochemical Performance of Deposited LiPON Film/Lithium Electrode in Lithium-Sulfur Batteries.

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium-sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium-sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium-sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium-sulfur batteries.

Reconstructing Helmholtz Plane Enables Robust F-Rich Interface for Long-Life and High-Safe Sodium-Ion Batteries.

Hard carbon (HC) is the most commonly used anode material in sodium-ion batteries. However, the solid-electrolyte-interface (SEI) layer formed in carbonate ester-based electrolytes has an imperceptible dissolution tendency and a sluggish Na+ diffusion kinetics, resulting in an unsatisfactory performance of HC anode. Given that electrode/electrolyte interface property is highly dependent on the configuration of Helmholtz plane, we filtrated proper solvents by PFBE (PF6 - anion binding energy) and CAE (carbon absorption energy) and disclosed the function of chosen TFEP to reconstruct the Helmholtz plane and regulate the SEI film on HC anode. Benefiting from the preferential adsorption tendency on HC surface and strong anion-dragging interaction of TFEP, a robust and thin anion-derived F-rich SEI film is established, which greatly enhances the mechanical stability and the Na+ ion diffusion kinetics of the electrode/electrolyte interface. The rationally designed TFEP-based electrolyte endows Na||HC half-cell and 2.8 Ah HC||Na4Fe3(PO4)2P2O7 pouch cell with excellent rate capability, long cycle life, high safety and low-temperature adaptability. It is believed that this insightful recognition of tuning interface properties will pave a new avenue in the design of compatible electrolyte for low-cost, long-life, and high-safe sodium-ion batteries.