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The corrosion property of aluminum by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is investigated in liquid and gel electrolytes consisting of ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20, vol %) with vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %) using conductivity measu...
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... foil (40 mm thick, purity > 99%) and lithium foil (purity > 99.9%) were supplied from Aldrich Chemicals. As a base electrolyte solution, 1 M LiTFSI dissolved in ethylene carbonate/propylene carbonate/ethylmethyl carbon- ate/diethyl carbonate (20:5:55:20, vol %) was used with additives of vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %). Three species of fumed silica with the average surface area of 100-260 ± 30 m 2 g −1 , designated as A200, R812, and R805 (Aerosil ® , Degussa), were used. The chemical structures of the silica particles are shown in Figure 1. The A200 is hydrophilic while the R812 and R805 are hydrophobic. According to the data of Aerosil ® , 22 the R812 and R805 are fumed silica powders after-treated from the A200 with a trimethylsiloxane and an octylsilane, respectively, to allow the carbon content of about 2.0-6.5 wt %. Preparation of electrolytes and cell assembly were done in a glove box under an argon gas ...
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... For the inorganic compounds additives, one is HF. A little of HF was added into LiCF 3 SO 3 /PC electrolyte, the anodic current was deceased without obvious pitting corrosion on Al. 109 The reason is that the HF helps Al to form a stable passivation layer with new composition. Fumed silica was another inorganic additive. ...
Aluminum (Al) current collector, an important component of lithium-ion batteries (LIBs), plays a crucial role in affecting electrochemical performance of LIBs. In both working and calendar aging of LIBs, Al suffers from severe corrosion issue, resulting in the decay of electrochemical performance. However, few efforts are devoted to the research of Al compared to anode and cathode materials, electrolyte, and even separators in LIBs. Here, the recent research advance in Al corrosion and protection is reviewed. We first briefly overview Al corrosion mechanism and its affecting factors. Then, the advanced technologies used to evaluate the electrochemical, morphology and chemical properties of Al are summarized in order to uncover the Al corrosion mechanism in LIBs. Next, we review the Al protection strategies in Al, electrolyte, and inhibitors with function mechanism, materials selection and their structural design. Finally, we outlook the future research direction in Al corrosion and protection. This review provides experimental and theoretical supports in understanding Al corrosion and development of Al anticorrosion, which will be beneficial to the research communities including corrosions, advanced materials, and energy storage devices.
... The first strategy is using suitable additives to electrolyte to inhibit the Al corrosion. Louis et al. 12 used fumed silica as electrolyte additive to suppress the Al corrosion in LIB. They indicated that silica particles form gel layer on the Al surface and this prevents the corrosive action of electrolyte. ...
... Fig. 2). The corrosion steps can be represented in the scheme 1 12 : As shown in the Fig. 2, the corrosion inhibition of coated Al foil with pristine PANI was achieved. The CV of the pristine PANI coated Al foil, on the other hand, shows an unstable pattern, suggesting that the permeated aggressive ions have started the corrosion process. ...
In electrochemical energy storage systems, Li-ion batteries have drawn considerable interest. However, the corrosion of the aluminum current collector in the LiN(SO 2 CF 3 ) 2 electrolyte has a major effect on battery efficiency. To protect the current collector from the corrosive action of the LiN(SO 2 CF 3 ) 2 electrolyte, new nanocomposites based on Ni(II)tetrakis[4-(2,4-bis-(1,1-dimethyl-propyl)-phenoxy)]phthalocyanine (Ni-Pc) and polyaniline matrix (PANI) (i.e. PANI@Ni-Pc composites) are coated on the aluminum current. SEM, XRD, and EDS were used to characterize the PANI@Ni-Pc composite. This method represents a novel approach to the production of Li-ion batteries. Electrochemical tests show that the PANI@Ni-Pc composites can protect aluminum from corrosion in LiN(SO 2 CF 3 ) 2 . The output of PANI@Ni-Pc composites is influenced by the Ni-Pc concentration. The composite PANI@Ni-Pc is a promising way forward to build high-stability Li-Ion batteries.
... Yang et al. associated the Al instability with LiTFSI to the reaction between this salt and the Al 2 O 3 passivation layer of the current collector, forming Al[N(CF 3 SO 2 ) 2 ] 3 and exposing the metallic Al to degradation [443]. Anti-corrosion strategies such as increasing the salt concentration in the electrolyte [444,445], using additives such as Pyr 14 TFSI [446] or fumed silica [447], or adding artificial coatings like carbon [448] or polymeric layers [449] have been proposed. ...
Lithium solid-state batteries (SSBs) are considered as a promising solution to the safety issues and energy density limitations of state-of-the-art lithium-ion batteries. Recently, the possibility of developing practical SSBs has emerged thanks to striking advances at the level of materials; such as the discovery of new highly-conductive solid-state electrolytes. Consequently, the focus in research has progressively shifted towards the integration of the various components, the battery's functionality at full cell level, and the scalability of the fabrication processes. Considering these points, the development of SSBs still faces formidable challenges. This review covers the recent advances in SSB development, stressing the importance of full cell integration. The most relevant materials and fabrication processes are briefly summarized and their potential applications in SSBs are examined. The main challenges and strategies for full cell integration are then discussed highlighting the most promising materials and the best suited processing techniques. Particular attention is paid on the mutual compatibility of the cell components, the properties of the interfaces within the cell (anode-electrolyte, cathode-electrolyte, intra-electrolyte) and the strategies applied to stabilize and minimize the resistance of these interfaces via compatible processing.
... This research utilizes Hydroxyl terminated Poly(dimethylsiloxane) (PDMS-HT), which consists of an -OH group at the end of each polymer chain as shown in Fig. 1, as an electrolyte additive for lithium ion batteries. The hydroxyl group has a low hindrance to bond rotation, can donate lone electron pairs for coordinating with cations, and has the ability to form hydrogen bonds in a liquid media to form networks that can facilitate Li + ion movement through the electrolyte medium leading to an improved ionic conductivity [10][11][12][13]. The -OH groups also have the ability to interact with electrolyte components such as EC leading to their decomposition that generates an SEI layer [10][11][12]. ...
... Ionic conductivities of 10.813; 11.913 and 11.375 mS cm − 1 were obtained for the pure electrolyte, with 0.2 wt% PDMS-HT, and 0.5 wt% PDMS-HT, respectively ( Table 1). The increase in ionic conductivity of the electrolytes with additives is partly attributed to the polar -OH groups that lead enhanced lithium salt dissociation and also formation of networks that enable Li + ion migration within the electrolyte [10][11][12][13][15][16][17]. Increasing the amount of additive beyond 0.5 wt% led to a decrease in ionic conductivity which could be as a result of bulky nature of the PDMS-HT (viscosity = 25 cSt) polymer chains leading to increased viscosity of the electrolytes [18]. ...
Hydroxyl terminated poly(dimethylsiloxane) (PDMS-HT) is used as an electrolyte additive in electrolyte systems containing 1 M LiPF6 in EC:DMC (ratios 1:9; 3:7; 4:6 and 1:1 v/v) to enhance the cycle performance of lithium-ion batteries. Adding a small amount of PDMS-HT to the standard LIB electrolyte leads to improved specific capacity as well as improved capacity retention over prolonged cycles. There is also a slight increase in Li⁺ ion conductivity when PDMS-HT is added. Also, the PDMS-HT additive allows the formation of a more stable solid electrolyte interface (SEI) layer that enables the LIB cells to be cycled for longer cycles with minimal capacity fading. This combination of improved ionic conductivity and stable SEI layer formation due to the PDMS-HT additive, makes it an excellent candidate for an electrolyte additive for lithium ion batteries.
... In lithium ion batteries the electrolyte can move freely within the cell and thus lead to unwanted side reactions. A common example is the reactions of the aluminum current collector with bis(trifluoromethanesulfonyl)imide (TFSI) containing ionic liquids [9]. This type of degradation mechanism can be avoided if the electrolyte is fixed between the electrodes. ...
Eight new polymerizable ammonium-TFSI ionic liquids were synthesized and characterized with respect to an application in energy storage devices. The ionic liquids feature methacrylate or acrylate termination as polymerizable groups. The preparation was optimized to obtain the precursors and ionic liquids in high yield. All products were characterized by NMR and IR spectroscopy. Phase transition temperatures were obtained by DSC analysis. Density, viscosity and ionic conductivity of the ionic liquids were compared and discussed. The results reveal that the length of attached alkyl groups as well as the methyl group at the polymerizable function have significant influences on the ionic liquids physicochemical properties. Ionic conductivity values vary between 0.264 mS cm−1 for [C2NA,22]TFSI and 0.080 mS cm−1 for [C8NMA,22]TFSI at 25 °C. Viscosity values are within a range of 0.762 Pa s for [C2NA,22]TFSI and 1.522 Pa s for [C6NMA,22]TFSI at 25 °C.
... 15,16 Combining LiPF 6 with lithium salts, such as LiTFSI, prevents Al dissolution in proportion to the fraction of LiPF 6 in the electrolyte. 11,12 Addition of certain retarding agents, such as C 4 F 9 SO 2 F 15 and fumed silica, 17 impedes this corrosion/dissolution but does not prevent it entirely. Growing a thick oxide layer on aluminum also slows down the corrosion but avoiding cracks in such coating during cell assembly becomes a technological challenge. ...
Presently, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, light-weight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X=TFSI) and lithium bis(fluorosulfonyl)imide (X=FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V vs. Li/Li+. For LiBF4 and LiPF6, the release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V vs. Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.
... No current was observed in our cells without LiTFSI. The shape of the voltammogram is similar to that reported in literature with liquid electrolyte containing LiTFSI (Krause et al., 1997;Louis et al., 2013;Wang et al., 2000). However, there are several distinct differences between our results with PEO-based polymer electrolyte and experiments with liquid electrolyte containing ethylene carbonate. ...
Polymer electrolytes are an interesting class of electrolytes that hold promise for safer, flexible, high-energy batteries. Block copolymer electrolytes that contain polystyrene, poly(ethylene oxide) (PEO) and lithium bis-trifluoromethanesulfonimide salt (LiTFSI) are compatible with lithium metal. However, the compatibility of PEO-based electrolyte with advanced lithium positive electrodes has not been conclusively demonstrated. Therefore, oxidative stability of PEO + LiTFSI and the block copolymer electrolyte with common current collectors and against inert working electrodes have been investigated electrochemically. The solid nature of these polymer electrolytes is a challenge for electrochemical investigations, since most electrochemical experiments have been designed for liquid electrolyte. In order to quantitatively evaluate polymer electrolyte stability, an electrochemical approach especially designed for solid electrolytes is presented. This approach uses a set of linear sweep voltammograms from different, large overpotentials to open circuit voltage, which the authors term variable reverse linear sweep voltammetry. By allowing the cell to relax between each polarization, the first data points of each voltammogram are not mass transfer limited. This yields current versus overpotential data that can be analyzed with a kinetic model, such as the Butler-Volmer model. The block copolymer electrolyte has been found to be quite stable to electrochemical oxidation, up to 5 V at 40 °C. The degradation reaction has been found to be slow with large thermal activation energy.
... It is well known that OH groups are commonly distributed on the surfaces of hydrophilic fumed silica and they connect with each other in liquid media through hydrogen interactions to form gels [19,22,23]. The porous networks of the gel make lithium ions move across the electrolyte medium, resulting in an increase in the ionic conductivity of LIB electrolytes [19,23e25]. ...
A lithium-modified silica nanosalt (Li–SiO2, coded Li202) of hydrophobic fumed silica (R202) is synthesized to use as an electrolyte additive for lithium-ion batteries (LIBs) under low temperature conditions. The synthesis method consists of reacting the silica nanoparticles with LiH and consequently quickly reacting the conjugate silicate ions with 1,3-propanesultone as a surface stabilizer. The obtained Li202 nanosalt (2.5 wt%) is added into an electrolyte solution of 1.0 M LiPF6 dissolved in ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20 vol%) + 2 wt% vinylene carbonate. The electrolyte solution including the Li202 nanosalt shows higher ionic conductivity and superior electrochemical stability over 5 V, which is due to the stabilized surface group. The high-rate capability at −20 °C of the LiCoO2/graphite cell is particularly enhanced by adding Li202 nanosalt. In addition, excellent cycle performance at −20 °C endorses the use of Li202 nanosalt as a low-temperature electrolyte additive for LIBs.
... With the addition of 5 wt.% of the Li202 into the conventional liquid electrolyte, significant improvements in ionic conductivity could be obtained over a wide temperature range [18]. The silica-based nanoceramic fillers may lead to form porous networks with the liquid electrolytes to yield a gel-state electrolyte [20] that can promote an easy conduction of ions to and from the electrode surfaces. In this study, though not arriving at an electrolyte with a perfect gel-state yet, slightly gelled surface between tiny flocculates are exhibited in the 'Electrolyte' þ Li202 (5 wt.%) electrolyte sample (not shown in the figure). ...
In this work, lithium-modified silica nanosalt (Li202) is solution-synthesized and used as a gel-forming additive in 1.5 M tetraethylammonium tetrafluoroborate (TEABF4)/acetonitrile (ACN) electrolyte solution for the supercapacitor with activated carbon electrode. The electrochemical properties of the supercapacitor adopting the Li202 (5 wt.%) are investigated using linear sweep voltammetry, cyclic voltammetry, and complex impedance spectroscopy. By the addition of the Li202, the electrochemical stability of the electrolyte is improved over 4.0 V (corresponding to the current density below 0.6 mA cm-2) and higher specific capacitances at the scan rates of 10-500 mV s-1 are obtained. Thus, the Li202 can be considered as a promising electrolyte additive to enhance the supercapacitive properties of activated carbon electrode.
Strategies towards inhibition of aluminum current collector corrosion in lithium batteries. Energy Mater 2023;3:300049. https://dx. Abstract Aluminum (Al) foil, serving as the predominant current collector for cathode materials in lithium batteries, is still unsatisfactory in meeting the increasing energy density demand of rechargeable energy storage systems due to its severe corrosion under high voltages. Such Al corrosion may cause delamination of cathodes, increasement of internal resistance, and catalysis of electrolyte decomposition, thus leading to premature failure of batteries. Hence, a systematic understanding of the corrosion mechanisms and effective anticorrosion strategies are necessary to enhance overall performance of lithium batteries. In this review, the corrosive mechanisms related to Al current collectors are systematically summarized and clarified. In addition, an overview on recent progress and advancement of strategies toward inhibiting Al corrosion is presented. In the end, we also provide a perspective with motivation to stimulate new ideas and research directions to further inhibit Al corrosion to achieve high energy density, long cycle life, and high safety of lithium batteries.
