Addition Of Vinylene Carbonate Research Articles

Influence of Vinylene Carbonate and Fluoroethylene Carbonate on Open Circuit and Floating SoC Calendar Aging of Lithium-Ion Batteries

The purpose of this study was to investigate the calendar aging of lithium-ion batteries by using both open circuit and floating current measurements. Existing degradation studies usually focus on commercial cells. The initial electrolyte composition and formation protocol for these cells is often unknown. This study investigates the role of electrolyte additives, specifically, vinylene carbonate (VC) and fluoroethylene carbonate (FEC), in the aging process of lithium-ion batteries. The results showed that self-discharge plays a significant role in determining the severity of aging for cells without additives. Interestingly, the aging was less severe for the cells without additives as they deviated more from their original storage state of charge. It was also observed that the addition of VC and FEC had an effect on the formation and stability of the solid electrolyte interphase (SEI) layer on the surface of the carbonaceous anode. By gaining a better understanding of the aging processes and the effects of different electrolyte additives, we can improve the safety and durability of lithium-ion batteries, which is critical for their widespread adoption in various applications.

Single Versus Blended Electrolyte Additives: Impact of a Sulfur‐Based Electrolyte Additive on Electrode Cross‐Talk and Electrochemical Performance of LiNiO2||Graphite Cells

AbstractLithium nickel oxide (LNO) is an attractive positive electrode active material for lithium ion batteries (LIBs) due to its high reversible specific capacity and absence of cobalt. Nevertheless, it is prone to structural instabilities that lead to rapid capacity fading, safety concerns and shows in average a lower voltage than mixtures with cobalt, limiting its applicability to date. Herein this study introduces the sulfur‐based electrolyte additive, benzo[d][1,3,2]dioxathiole 2,2‐dioxide (DTDPh), to stabilize the LNO electrode and study its effects on interphase compositions by means of complementary electrochemical and spectroscopic techniques. Obtained results demonstrate an improved galvanostatic cycling performance in terms of cycle life and achievable specific discharge capacity that significantly outperform the common film‐forming additive vinylene carbonate (VC). The cycle life is increased from 102 to 147 cycles compared to the baseline electrolyte and the accumulated discharge energy until end of life is increased by 45%. This study furthermore provides strong evidence of a significant cross‐talk and negative interplay between DTDPh and VC when both are present in the electrolyte formulation. Mechanistic consideration based on density functional theory (DFT) calculations suggest the formation of mobile poly(VC) species, which is supported by the results of post mortem analysis of the resulting interphases.

IDENTIFYING THE ROLE OF ELECTROLYTE ADDITIVES FOR LITHIUM PLATING ON GRAPHITE ELECTRODE BY OPERANDO X‐RAY TOMOGRAPHY

The plating of lithium on the graphite electrode is a major degradation mechanism in lithium‐ion batteries (LIBs) and brings safety concerns and leads to short cycle life. Understanding how and when plating occurs is crucial for the development of mitigation strategies, e.g. tuning the electrolyte composition. We present an operando X‐ray tomographic microscopy study to monitor the plating of lithium on a graphite electrode. XTM enables non‐destructive, quantitative operando characterization of lithium deposition and allows us to probe the role of the electrolyte additives vinylene carbonate and lithium bis(fluorosulfonyl)imide in the standard electrolyte LP57. The additives show a better performances in terms of delayed onset of lithium plating, important to utilise the full capacity of the graphite, since once lithium plating is initiated this rapidly becomes dominating and hinders further intercalation. For the base electrolyte a homogeneous and dense morphology of plated lithium is found, whereas a more dendritic morphology is observed in the presence of additives. During delithiation, there is a rapid stripping of some of the plated lithium followed by deintercalation. In addition, our work provides a general methodology to track the morphology of plated lithium, which is crucial for fundamental research about battery safety.

Solid Electrolyte Interphase Formation at the Ionic Liquid Electrolyte—Lithium-Metal Interface Using an Ab Initio Molecular Dynamics Approach

An interfacial study is performed using ab initio molecular dynamics (AIMD) simulations to elucidate the electrochemical interfacial stability of an ionic liquid (IL) as component of an electrolyte in contact with a Li-metal anode when an additive, vinylene carbonate (VC), is added to the electrolyte. The IL electrolyte is composed of 1-butyl-1-methylpyrrolidinium bis(fluoro-sulfonyl)-imide (PYR14+FSI−) with lithium bis(trifluoromethane-sulfonyl)imide salt (Li+TFSI−) in a 8:2 concentration ratio. Reactions observed at the interface electrolyte/Li-metal during the AIMD simulations are verified by electronic structure calculations using density functional theory calculations considering a continuum solvent model. We found that the addition of VC to the IL prevents further reduction of the counter-ion TFSI− and retards reduction of FSI− in comparison to the case when the additive VC is absent. The PYR14+ reduction is never observed with or without the additive. The 1st, 2nd, and 3rd electron affinities of the PYR14+ are −0.08, −0.36 and −3.65 eV, indicating little to large repulsive behavior against electrons. The opposite is observed for the two negative ions, FSI− and TFSI−, which yield 1st electron affinities of 1.73 and 1.83 eV, respectively. Reactions obtained under open circuit conditions. Dissociation mechanisms are presented for all IL components reduced at the IL/Li-metal interface.

Blended Salt Electrolyte Design for Enhanced NMC811||Graphite Cell Performance

The high energy density, nickel‐rich layered cathode material LiNi0.8Mn0.1Co0.1O2 (NMC811) is recognized as a promising candidate for next‐generation battery chemistries. However, due to their structural and interfacial instability, nickel‐rich NMC cathodes still face a number of challenges in practical application. For this reason, the design and development of novel electrolyte formulations, able to stabilize the nickel‐rich cathode|electrolyte interface, are highly demanded. In this work, a novel electrolyte is developed using lithium (difluoromethanesulfonyl) (trifluoromethanesulfonyl)imide (LiDFTFSI) and lithium hexafluorophosphate (LiPF6) as salt blend in an organic carbonate‐solvent based solvent mixture. The presence of LiDFTFSI notably enhances the electrochemical performance of the resulting NMC811||graphite cells. Further advancement of the considered cell chemistry is achieved by introducing the well‐known functional electrolyte additive vinylene carbonate (VC), which was found to feature a synergistic effect with LiDFTFSI. The formation of a homogenous, effective, and robust solid electrolyte interphase (SEI) as well as cathode electrolyte interphase (CEI) on the corresponding electrodes resulted in superior electrochemical performance.

Investigating the Reaction Mechanism of Vinylene Carbonate Additive in Lithium Ion Batteries Using X-Ray Photoelectron Spectroscopy

The rechargeable Li-ion battery is an enabling technology which facilitates the electrification of the automotive industry and reduces the demand for fossil fuels. During the charge and discharge of a battery, a solid-electrolyte interphase (SEI) forms between the liquid electrolyte and the solid negative electrode as a result of electrolyte degradation. The chemical and physical stability and the functionality of the SEI is a key determining factor of battery performance. The chemical composition of the SEI is mainly controlled by the choice of solvent and salt used, but can be manipulated by the addition of electrolyte additives that influence the electrolyte degradation process.Vinylene carbonate (VC) is an additive used in many commercial Li-ion battery configurations. The addition of a small amount of VC to ethylene carbonate (EC) containing electrolytes has been demonstrated to drastically improve several performance metrics for batteries including cycle life, coulombic efficiencies, capacity retention and thermal stability. The success of VC is widely attributed to its ability to form a thinner, denser and more robust SEI, which better protects the electrode surface and prevents further electrolyte consumption. This improvement in stability has been linked to the presence of poly(VC) in the SEI, but the mechanism by which VC reacts in EC-containing electrolytes is still an area of ongoing study. Whilst computational methods have suggested several potential decomposition pathways of electrolytes containing VC, it is yet to be convincingly demonstrated experimentally. Whilst there is a general consensus about ‘What?’ forms in the SEI on the addition of VC to EC-containing solvent, this work aims to confirm ‘Where?’ these components are in the interface and the currently unanswered questions of ‘How?’ and ‘Why?’ they form.Using highly surface sensitive photoelectron spectroscopy (PES) measurements of the SEI deposited at various potentials, we identify the differences in composition and structure that result from the addition of VC additive to EC-containing electrolytes. The SEI formation is studied using a smooth Au surface as the model working electrode and a fluorine free EC:diethyl carbonate (DEC) (1:9) 1 M LiClO4 electrolyte in an attempt to isolate the impact of VC on the SEI. A potential step procedure allows analysis of the working electrode surface by PES at several progressively more negative potentials on the first charge. Through systematic variation of components such as the concentration of VC, the ratio of EC:DEC and swapping Au for other electrode materials such as Cu or Si, the interaction between VC, EC and the electrode surface is revealed. The differences in SEI composition and structure formed in each environment and at each potential step are correlated to quartz crystal microbalance (QCM) data in order to identify potential reaction mechanisms and formation processes. The results play a key role in understanding the reaction pathway of VC-containing electrolytes and will accelerate development of more efficient electrolyte additives.

Visualization of Lithium Plating Morphologies on Graphite Electrode By O perando X-Ray Tomography

The plating of lithium metal on graphite electrodes in Li-ion batteries is a major factor limiting the fast charging of electric vehicles. Lithium metal plating leads to the growth of dendritic structures that can pierce through the battery’s separator resulting in an internal short circuit and catastrophic failure of the battery. Moreover, the plating of lithium metal on graphite is not reversible, manifesting in poor Coulombic efficiency, severe reduction of the battery’s life expectancy, and safety issues. Understanding how and when plating occurs in Li-ion batteries is crucial in the development of strategies to prevent plating under fast charging conditions. Thus, we have conducted an operando X-ray tomographic microscopy experiment to directly monitor the plating of lithium metal in a Li/Graphite cell when applying electrolytes with the additives vinylene carbonate (VC) and Lithium bis(fluorosulfonyl)imide (LiFSI). The experiment was performed at the ID19 beamline (ESRF, France) where tomographic scans, linked with the lithiation state of graphite, made it possible to gain a strong understanding of the mechanisms behind Li-deposition and stripping at high current rates in addition to understand the effect of the VC and LiFSI additives.

In Situ Electron Paramagnetic Resonance Monitoring of Predegradation Radical Generation in a Lithium Electrolyte.

Herein we present an innovative in situ EPR spectroscopy approach complemented with computational modeling as a methodology for assessing a nonaqueous electrolyte behavior just before its massive degradation. As a proof of concept, we use the conventional lithium electrolyte (1 M LiPF6 in EC/DMC), which is utilized in current lithium-ion batteries. Through in situ EPR, long-lived EC•- associates in amounts of 10-250 ppm were detected in a broad potential window (>2.0 V) prior to the electrolyte oxidation or reduction. The pathways of radical formation are discussed in terms of the imperfection in the electron flow across the electrolyte-electrode interface and of the strong affinity of EC to electron trapping. The radical amount could be amplified markedly (above 1000 ppm) by addition of vinylene carbonate (VC) to the electrolyte, while the added CeO2 has a moderate effect. The proposed in situ EPR methodology could be transferred to other electrolyte solutions to become a universal approach.

Abnormal electrode behavior of graphite anode operating with the electrolyte containing vinylene carbonate and ethylene sulfite additives

Supplementing additives into the electrolyte is a simple and effective approach to improve the electrode performance of lithium-ion batteries (LIBs). Although vinylene carbonate (VC) and ethylene sulfite (ES) additives have been studied to improve the performance of LIBs with graphite anode, the abnormal electrode behavior of graphite anodes operating with the electrolyte containing VC and ES additives has never been reported. In this paper, we report on the discovery and interpretation of the room-temperature capacity anomaly of graphite anodes operating with the VC-ES electrolyte at relatively high C rates (≥ 0.5 C). A dynamic evolution mechanism of SEI is proposed on the basis of electrochemical analysis and surface examination of graphite anodes at different charge/discharge states. The merit of the VC-ES electrolyte over the VC electrolyte is found for graphite anodes operating at 55 ºC. The VC-ES electrolyte provided here holds great potential for application in LIBs with graphite anode operating at high temperatures.

Solid–Electrolyte Interface Formation on Si Nanowires in Li-Ion Batteries: The Impact of Electrolyte Additives

The morphological changes of Si nanowires (Si NWs) cycled in 1:1 ethylene–carbonate (EC)/diethyl–carbonate (DEC) with or without different additives, fluoroethylene carbonate (FEC) or vinylene carbonate (VC), as well as the composition of the deposited solid–electrolyte interphase layer, are investigated by a combination of experimental microscopic and spectroscopic techniques. Scanning electron microscopy and optical spectroscopy highlight that the NW morphology is better preserved in samples cycled in the presence of FEC and VC additives compared to the additive-free electrolyte. However, only the use of FEC is capable of slightly mitigating the amorphization of silicon upon cycling. The solid electrolyte interphase (SEI) formed over the Si NWs cycled in the additive-free electrolyte is richer in organic and inorganic carbonates compared to the SEI grown in the presence of the VC and FEC additives. Furthermore, both additives are able to remarkably limit the degradation of the LiPF6 salt. Overall, the use of the FEC-additive in the carbonate-based electrolyte promotes both morphological and structural resilience of the Si NWs upon cycling thanks to the optimal composition of the SEI layer.

Redox of anionic and cationic radical intermediates in a bipolar polyimide COF for high-performance dual-ion organic batteries

Bipolar organic materials for dual-ion batteries have attracted immense attention due to the low cost, high theoretical capacity, and potential sustainability. However, the bipolar organic batteries are plagued by low reversible capacity and poor stability. Herein, a novel bipolar polyimide COF with n-type imide units and p-type quaternary nitrogen centers exhibits unique topology structure and is used for dual-ion organic batteries. Detailed analyses reveal that the redox of anionic imide radicals and cationic nitrogen-center radicals was triggered to store the Li+ ions and PF6− anions, respectively, during the charge/discharge processes. Electrolyte engineering demonstrates that the electrolyte additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) would inactivate the imide units and result in low capacities and poor reversibility of the COF electrodes. With the unique structure and optimized electrolyte, the bipolar COF exhibits high capacity of 165 mAh/g at 30 mA/g and high capacity retention of 91 % after 4000 cycles at 1 A/g, surpassing most of the bipolar electrodes. This work not only expands the palette to design bipolar materials for rechargeable batteries but also emphasizes the importance of the matching strategy of electrolytes and organic electrodes.

Towards a Better Understanding of Redox Shuttle Generation in Lfp/Graphite and NMC811/Graphite Cells By Systematic Investigation of Different Electrolyte Additives

Recent observations by our group show the creation of a reversible shuttle species in LFP/graphite and NMC811/graphite cells with 3:7 ethylene carbonate:dimethyl carbonate (EC:DMC) based electrolytes. This is indicated by a high reversible self-discharge of these cells in the absence of electrolyte additives. Electrolyte extraction from pouch cells after formation allowed to directly investigate the electrolytes for redox shuttle currents. For this purpose, the extracted electrolytes were inserted into coin cells with an Al foil as the working electrode (WE) and a Li foil as the counter electrode (CE). The measured cyclic voltammetry (CV) of the coin cells show a clear relationship between high formation temperature and high shuttle currents. Interestingly, the addition of vinylene carbonate (VC) to the electrolyte completely prevents the shuttle current, even at elevated formation temperatures. [1]In this study, we systematically investigate the effect of various electrolyte additives on the generation of shuttle molecules. LFP/graphite and NMC811/graphite pouch cells were filled with electrolyte consisting of 3:7 EC:DMC with 1.5 M lithium hexafluorophosphate (LiPF6) and different additives. The pouch cells were formed at different temperatures, TF. The electrolytes were then extracted and inserted into the aforementioned coin cell setup for CV measurements.We have found that additives such as VC, fluoroethylene carbonate (FEC), ethylene sulfate (DTD), prop-1-ene-1,3-sultone (PES), and triallyl phosphate (TAP), which are known to create a stable solid electrolyte interphase (SEI), [2-4] prevent shuttle current in the CV. On the other hand, additives such as succinonitrile (SN) and trimethylsilyl isothiocyanate (TMSNCS), which do not contribute to the formation of a better SEI, [5,6] cannot prevent the shuttle current. This suggests that the formation of the shuttles is due to a poor SEI and therefore occurs at the interface between electrolyte and graphite anode.Analogue experiments with DMC as only solvent instead of 3:7 EC:DMC show similar shuttle currents in CVs, which suggests that linear carbonates such as DMC are required to form the shuttle.Figure 1 shows CVs for 1.5 M LiPF6 DMC electrolyte. The shuttle current appears to be the same for electrolyte extracted from LFP/graphite and NMC811/graphite cells ranging up to 6 μA in both cases. This indicates that the shuttle is formed independently of the cathode material, and therefore gives rise to the hypothesis that it is formed at the anode-electrolyte interface. Figure 1 also shows that the shuttle current increases with higher formation temperatures TF.

Back to the basics: Advanced understanding of the as-defined solid electrolyte interphase on lithium metal electrodes

The design and control of the solid electrolyte interphase (SEI) is essential for the implementation of rechargeable lithium metal based batteries and has been a major research theme of lithium metal electrodes for over 50 years. However, research on an as-defined SEI is challenging due to the inevitable presence of a native passivation layer (NPL), commonly contaminating an in situ formed SEI and its characteristics. Herein we present an original study on an uncontaminated SEI being an exclusive reaction product of lithium and a liquid aprotic electrolyte, highlighting the largely negative influence of the NPL on different SEI characteristics and functional additive evaluation. A preformed as-defined SEI (pSEI) was generated by an in-house designed advanced pre-treatment method, ensuring high reproducibility and exclusion of the NPL by cutting and pressing lithium metal in solution/electrolyte. The implementation of a pSEI allows for a systematic study and an unclouded comparison of the two common functional additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in an equal molar setting. The introduction of an as-defined SEI allowed to clearly distinguish between enhancing influence on the SEI characteristics and full cell performance by FEC and the largely negative effect of VC on different SEI characteristics.

Effect of Vinylene Carbonate Electrolyte Additive on the Process of Insertion/Extraction of Na into Ge Microrods Formed by Electrodeposition

Layers of germanium (Ge) microrods with a core–shell structure on titanium foils were grown by a metal-assisted electrochemical reduction of germanium oxide in aqueous electrolytes. The structural properties and composition of the germanium microrods were studied by means of scanning and transmission electron microscopy. Electrochemical studies of germanium nanowires were carried out by impedance spectroscopy and cyclic voltammetry. The results showed that the addition of vinylene carbonate (VC) in the electrolyte significantly reduced the irreversible capacity during the first charge/discharge cycles and increased the long-term cycling stability of the Ge microrods. The obtained results will benefit the further design of Ge microrods-based anodes that are formed by simple electrochemical deposition.

Re-evaluating common electrolyte additives for high-voltage lithium ion batteries

Further increase in the specific energy/energy density of lithium ion batteries can be achieved via further increase of charge cell voltage. However, an enhanced electrode cross-talk, i.e., transition metal (TM) dissolution from cathode and deposition on the anode, drastically limits the cycle life, even leading to rollover failure. In this work, the commonly used film-forming electrolyte additives vinylene carbonate (VC), fluoroethylene carbonate (FEC), and lithium difluorophosphate (LiDFP) are thoroughly evaluated regarding their ability to suppress the issues originating from electrode cross-talk. Neither the VC- nor the FEC-containing electrolytes can suppress it, as evidenced by the presence of Ni, Co, and Mn on the graphite anode; although different for the FEC, the deposited TMs and intertwined Li deposits are homogeneously distributed in the presence of VC. Despite suppression of rollover failure in this manner, VC still cannot compete with LiDFP because LiDFP is able to complex TMs and provide TM-scavenging agents, i.e., PO 3 F − and PO 4 2− , thus, effectively suppressing electrode cross-talk in the first place and effectively preventing the concomitant failure cascade. TM-based electrode cross-talk causes Li dendrites and rollover failure Neither VC nor FEC can suppress electrode cross-talk At a minimum, VC promotes homogeneous TM deposition and suppresses rollover failure LiDFP is most effective because it suppresses electrode cross-talk via scavenging Further increases in energy density of Li-ion batteries can be realized by increasing the charge voltage. However, the enhanced transition-metal dissolution from the cathode and deposition on the anode causes severe safety and performance issues. Klein et al. show that scavenging of transition metals can ameliorate those issues.

Lithiation/Delithiation Properties of Lithium Silicide Electrodes in Ionic-Liquid Electrolytes.

We investigated the impact of electrolyte difference on lithiation and delithiation properties of a Li1.00Si electrode to improve the Coulombic efficiency (CE) of Si-based electrodes. The results of X-ray diffraction, Raman spectroscopy, and soft X-ray emission spectroscopy demonstrated that a portion of the Li in Li1.00Si desorbed by simply immersing the electrode in an ionic-liquid electrolyte, that is, the phase transition of Li1.00Si to Si occurred. In contrast, this phenomenon was not confirmed in an organic-liquid electrolyte. Instead, the desorbed Li was consumed for the formation of a surface film; thus, the Li in Li1.00Si did not elute into the electrolyte. The addition of vinylene carbonate (VC) to the ionic-liquid electrolyte suppressed the phase transition of Li1.00Si to Si. Although the Li1.00Si electrode showed a low initial CE and poor cycling performance in a VC-free electrolyte, the electrode exhibited a high CE and a remarkable cycle life in the VC-added electrolyte. It was considered that no desorption of the mechanically added Li in Li1.00Si contributed to the superior cycle life; thus, the characteristic ductility, malleability, and high electrical conductivity of lithium silicide should improve the electrochemical performance.

Effect of fluoroethylene carbonate and vinylene carbonate additives on full-cell optimization of Li-ion capacitors

Lithium-ion capacitors (LICs) operate by two mechanisms, namely a double-layer mechanism based on a capacitor-like positive electrode and the intercalation mechanism of a battery-like negative electrode. Hence, well-designed reaction kinetics between the positive electrode and negative electrode are essential for optimizing LIC full-cell configurations. In this study, we investigated the influences of fluoroethylene carbonate (FEC) or vinylene carbonate (VC) as electrolyte additives on full-cell performance of LICs. We confirmed that the internal resistance of graphite increased with the use of FEC, which degraded the cyclability of the LIC full-cell. Conversely, LICs consisting of the VC additive had good cyclability over 4000 cycles owing to the solid electrolyte interphase (SEI) containing polymeric species. This detailed investigation into the function of SEI compounds derived from VC additives and their effect on cyclability will provide new insights into optimization of LIC full-cell configurations with appropriate electrolyte additives.

High‐Rate Lithium‐Ion Cycling in Electrodeposited Binder‐Free Thin‐Film Vanadium Oxide Cathodes with Lithium Metal Anodes in Ionic Liquid and Polymer Gel Analogue Electrolytes

AbstractHigh rate and long cycle life performance for electrodeposited, binder‐free V2O5 thin film cathodes and lithium metal anodes is described using liquid and polymer gel electrolytes of the pyrrolidinium based (C4mpyrTFSI) ionic liquid (IL). Sharp well‐defined voltammetric peaks typically seen with nanostructured V2O5 materials in organic electrolytes, support the fast kinetics observed. The addition of vinylene carbonate (VC) stabilises the electrolyte interface leading to higher electrode capacities than for the additive‐free electrolyte, ∼120 versus ∼90 mAh g−1 at 0.75 C. Polymer gel electrolytes based on the IL yield similar electrode capacities, coulombic efficiencies and high rate performances without the VC‐additive. The polymer gel option delivers the better long‐term stability up to 400 cycles with lithium metal anodes with minimal capacity fade at elevated charge and discharge rates up to 5 C.

Machine learning approach in exploring the electrolyte additives effect on cycling performance of LiNi 0 . 5 Mn 1 . 5 O 4 cathode and graphite anode‐based lithium‐ion cell

LiNi0.5Mn1.5O4 (LNMO), a high-voltage spinel, has attracted great attention owing to its low cost and high operating voltage. Many great efforts have been devoted to developing full-cell of LNMO/graphite because of electrolyte oxidation issues at such high voltage. In this work, the effect of additives including vinylene carbonate (VC) and lithium bis(oxalate)borate (LiBOB) in carbonate-based electrolytes was investigated on LNMO/Li and graphite/Li to find out the optimized electrolyte composition. The use of additives in 1.0 M LiPF6 in EC:DMC (1:1 v/v) seemed not to give any improvement on the electrochemical behavior of the cell. In the case of 1.2 M LiPF6 in EC:EMC (3:7 v/v), however, both half-cells of LNMO and graphite exhibited stability of discharge capacity during long cycling with the presence of LiBOB or VC additives. Based on the artificial neural network (ANN) simulation, the best electrochemical performance would obtain for LNMO/Li in the electrolyte of 0.67 M LiPF6 in EC:DMC:EMC (2.9:3.5:3.6 (v/v) with 0.41 wt% LiBOB and 1.17 wt% VC additives cell, which delivered 141.1 mAh.g−1 and remained 90% capacity after 100 cycles when using. Also, it predicted that the graphite/Li in the electrolyte of 1.34 M LiPF6 in EC:DMC:EMC (6.2:1.2:2.6) (v/v) with a 0.08 wt% LiBOB additive would achieve 342.2 mAh.g−1 and 85% of capacity retention after 100 cycles. The machine learning approach is efficient in exploring the effect of additive and simultaneously searching an optimization of many design parameters and thus saving the significant cost of time-consuming experiments.

Achieving long-cycling sodium-ion full cells in ether-based electrolyte with vinylene carbonate additive

The sodium-ion full cell can be employed in the ether-based electrolyte by the addition of VC and exhibits long term cycling stability and high capacity retention. • NaCF 3 SO 3 -DGM + 5wt% VC electrolyte could make sodium-ion full cells applicable. • The sodium-ion full cell with the electrolyte exhibits long term cycling stability. • VC can be synergistically oxidized with DGM to form integrity CEI layers. Application of sodium-ion batteries is suppressed due to the lack of appropriate electrolytes matching cathode and anode simultaneously. Ether-based electrolytes, preference of anode materials, cannot match with high-potential cathodes failing to apply in full cells. Herein, vinylene carbonate (VC) as an additive into NaCF 3 SO 3 -Diglyme (DGM) could make sodium-ion full cells applicable without pre-activation of cathode and anode. The assembled FeS@C || Na 3 V 2 (PO 4 ) 3 @C full cell with this electrolyte exhibits long term cycling stability and high capacity retention. The deduced reason is additive VC, whose HOMO level value is close to that of DGM, not only change the solvent sheath structure of Na + , but also is synergistically oxidized with DGM to form integrity and consecutive cathode electrolyte interphase on Na 3 V 2 (PO 4 ) 3 @C cathode, which could effectively improve the oxidative stability of electrolyte and prevent the electrolyte decomposition. This work displays a new way to optimize the sodium-ion full cells easily with bright practical application potential.