The decomposition of state‐of‐the‐art lithium ion battery (LIB) electrolytes leads to a highly complex mixture during battery cell operation. Furthermore, thermal strain by e.g., fast charging can initiate the degradation and generate various compounds. The correlation of electrolyte decomposition products and LIB performance fading over life‐time is mainly unknown. The thermal and electrochemical degradation in electrolytes comprising 1 m LiPF6 dissolved in 13C3‐labeled ethylene carbonate (EC) and unlabeled diethyl carbonate is investigated and the corresponding reaction pathways are postulated. Furthermore, a fragmentation mechanism assumption for oligomeric compounds is depicted. Soluble decomposition products classes are examined and evaluated with liquid chromatography‐high resolution mass spectrometry. This study proposes a formation scheme for oligo phosphates as well as contradictory findings regarding phosphate‐carbonates, disproving monoglycolate methyl/ethyl carbonate as the central reactive species. 相似文献
Solid‐state electrolytes have emerged as a promising alternative to existing liquid electrolytes for next generation Li‐ion batteries for better safety and stability. Of various types of solid electrolytes, composite polymer electrolytes exhibit acceptable Li‐ion conductivity due to the interaction between nanofillers and polymer. Nevertheless, the agglomeration of nanofillers at high concentration has been a major obstacle for improving Li‐ion conductivity. In this study, we designed a three‐dimensional (3D) nanostructured hydrogel‐derived Li0.35La0.55TiO3 (LLTO) framework, which was used as a 3D nanofiller for high‐performance composite polymer Li‐ion electrolyte. The systematic percolation study revealed that the pre‐percolating structure of LLTO framework improved Li‐ion conductivity to 8.8×10?5 S cm?1 at room temperature. 相似文献
New polymer gel electrolytes based on polyester diacrylates and LiClO4 salt solutions in organic solvents are developed for lithium ion and lithium polymer batteries with a high ionic conductivity up to 2.7 × 10?3 Ohm?1cm?1 at the room temperature. To choose the optimum liquid electrolyte composition, the dependence is studied of physico-chemical parameters of new gel electrolytes on the composition of the mixture of aprotic organic solvents: ethylene carbonate, propylene carbonate, and λ-butyrolacton. The bulk conductivity of gel electrolytes and exchange currents at the gel electrolyte/Li interface are studied using the electrochemical impedance method in symmetrical cells with two Li electrodes. The glass transition temperature and gel homogeneity are determined using the method of differential scanning calorimetry. It is found that the optimum mixture is that of propylene carbonate and λ-butyrolacton, in which a homogeneous polymer gel is formed in a wide temperature range of ?150 to +50°C. 相似文献
A new super‐concentrated aqueous electrolyte is proposed by introducing a second lithium salt. The resultant ultra‐high concentration of 28 m led to more effective formation of a protective interphase on the anode along with further suppression of water activities at both anode and cathode surfaces. The improved electrochemical stability allows the use of TiO2 as the anode material, and a 2.5 V aqueous Li‐ion cell based on LiMn2O4 and carbon‐coated TiO2 delivered the unprecedented energy density of 100 Wh kg?1 for rechargeable aqueous Li‐ion cells, along with excellent cycling stability and high coulombic efficiency. It has been demonstrated that the introduction of a second salts into the “water‐in‐salt” electrolyte further pushed the energy densities of aqueous Li‐ion cells closer to those of the state‐of‐the‐art Li‐ion batteries. 相似文献
The resurgence of the lithium metal battery requires innovations in technology, including the use of non‐conventional liquid electrolytes. The inherent electrochemical potential of lithium metal (?3.04 V vs. SHE) inevitably limits its use in many solvents, such as acetonitrile, which could provide electrolytes with increased conductivity. The aim of this work is to produce an artificial passivation layer at the lithium metal/electrolyte interface that is electrochemically stable in acetonitrile‐based electrolytes. To produce such a stable interface, the lithium metal was immersed in fluoroethylene carbonate (FEC) to generate a passivation layer via the spontaneous decomposition of the solvent. With this passivation layer, the chemical stability of lithium metal is shown for the first time in 1 m LiPF6 in acetonitrile. 相似文献
A random copolymer of ethylene oxide with CO2, namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm−1 and a Li transference number (t +) of 0.66 at 60 °C. To study ion‐conductive behavior of P(EC/EO)‐based electrolytes, the Fourier transform infrared (FT‐IR) technique is used to analyze the interactions between Li+ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li+ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t + for polymer electrolytes. High‐performance P(EC/EO) electrolyte is expected to be a candidate material for use in all‐solid‐state batteries.
Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) gel electrolytes comprising a combination of plasticizers, ethylene carbonate (EC) and propylene carbonate (PC) and lithium salt LiX have been prepared using the solution casting technique in an argon atmosphere. The prepared electrolytes were subjected to ionic conductivity, compatibility with lithium metal anode and thermogravimetric (TG)/differential thermal analysis (DTA). The membranes, which possess lithium salt, LiBF4 exhibited maximum conductivity and on contrary it undergoes severe passivation with lithium metal. All these membranes are found to be stable thermally about 70 °C. 相似文献
Titanium dioxide (TiO2) is considered a promising anode material for high‐power lithium ion batteries (LIBs) because of its low cost, high thermal/chemical stability, and good safety performance without solid electrolyte interface formation. However, the poor electronic conductivity and low lithium ion diffusivity of TiO2 result in poor cyclability and lithium ion depletion at high current rates, which hinder them from practical applications. Herein we demonstrate that hierarchically structured TiO2 microboxes with controlled internal porosity can address the aforementioned problems for high‐power, long‐life LIB anodes. A self‐templating method for the synthesis of mesoporous microboxes was developed through Na2EDTA‐assisted ion exchange of CaTiO3 microcubes. The resulting TiO2 nanorods were organized into microboxes that resemble the microcube precursors. This nanostructured TiO2 material has superior lithium storage properties with a capacity of 187 mAh g−1 after 300 cycles at 1 C and good rate capabilities up to 20 C. 相似文献
Plasticized polymer electrolytes were prepared using poly(ethylene oxide)(PEO)/poly(vinylidene fluoridehexafluoro propylene)(PVd F-HFP) with lithium perchlorate(Li Cl O4) and different plasticizers. XRD and FTIR spectroscopic techniques were used to characterize the structure and the complexation of plasticizer with the host polymer matrix. The role of interaction between polymer hosts and plasticizer on conductivity is discussed using the results of alternating current(a.c.) impedance studies. TG-DTA and SEM were used for thermal and physical characterizations. Maximum ionic conductivity(3.26 × 10~(-4) S·cm~(-1)) has been observed for ethylene carbonate(EC)-based polymer electrolytes. Electrochemical performance of the plasticized polymer electrolyte is evaluated in LiFePO_4/plasticized polymer electrolytes(PPEs)/Li coin cell. Good performance with low capacity fading on charge discharge cycling is demonstrated. 相似文献
A strategy is described to increase charge storage in a dual electrolyte Na‐ion battery (DESIB) by combining the redox chemistry of the electrolyte with a Na+ ion de‐insertion/insertion cathode. Conventional electrolytes do not contribute to charge storage in battery systems, but redox‐active electrolytes augment this property via charge transfer reactions at the electrode–electrolyte interface. The capacity of the cathode combined with that provided by the electrolyte redox reaction thus increases overall charge storage. An aqueous sodium hexacyanoferrate (Na4Fe(CN)6) solution is employed as the redox‐active electrolyte (Na‐FC) and sodium nickel Prussian blue (Nax‐NiBP) as the Na+ ion insertion/de‐insertion cathode. The capacity of DESIB with Na‐FC electrolyte is twice that of a battery using a conventional (Na2SO4) electrolyte. The use of redox‐active electrolytes in batteries of any kind is an efficient and scalable approach to develop advanced high‐energy‐density storage systems. 相似文献