Carbonate-Based Liquid Electrolyte

The development of high performance electrolytes is an important task in the production of devices for electric energy storage and delivery such as lithium ion batteries, capacitors, and electrochromic devices. Carbonate-based materials are one of the liquid electrolytes. Carbonate-based liquid electrolytes are now commonly used for the economical lithium ion batteries [31]. The solution of carbonate and lithium salts exhibits high ionic conductivity, on the order of 10-3 S cm-1 at ambient temperature. 

Mizuno, R Nakanishi, S. Kotam, Y. Yokoishi, S. Iba, H., Rechargeable Li-air batteries with carbonate-based liquid electrolytes.. Electrochemistry, 2010,78,403 05. 

Mizuno F, Nakanishi S, Kotani Y, Yokoishi S, Iba H (2010) Rechargeable li-air batteries with carbonate-based liquid electrolytes (E). Electrochem 78 403 105... 

In fact, conductivity due to the Li" cation transport only in [pyri3][TFSI] + 0.25 LiTFSI was found to be somewhat greater than that for a model poly(ethylene oxide)(PEO-based)/LiTFSI polymer electrolyte but 1-2 orders of magnitude lower than conductivity of ethylene carbonate/LiTFSI liquid electrolyte depending on temperature [86]. 

An atomistic simulation MD simulation of a common carbonate-based organic electrolyte, ethylene carbonate dimethyl carbonate (EC DMC = 3 7) with approximately 1 mol/kg LiPFs, referred to as the organic liquid electrolyte or OLE, and an ionic liquid-based electrolyte (ILE), 1-ethyl 3-methyl-imidazolium bis (fluorosulfonyl)imide (EMIM iFSE) with 1 mol/kg LiFSI, in contact with LiFeP04 has been carried out [107]. Simulations were carried out using quantum chemistry-based polarizable force at 363 K on a 3-D periodic orthorhombic... 

The preparation and properties of a novel, commercially viable Li-ion battery based on a gel electrolyte has recently been disclosed by Bellcore (USA) [124]. The technology has, to date, been licensed to six companies and full commercial production is imminent. The polymer membrane is a copolymer based on PVdF copolymerized with hexafluoropropylene (HFP). HFP helps to decrease the crystallinity of the PVdF component, enhancing its ability to absorb liquid. Optimizing the liquid absorption ability, mechanical strength, and processability requires optimized amorphous/crystalline-phase distribution. The PVdF-HFP membrane can absorb plasticizer up to 200 percent of its original volume, especially when a pore former (fumed silica) is added. The liquid electrolyte is typically a solution of LiPF6 in 2 1 ethylene carbonate dimethyl car-... 

In the last paper, A. Lewandowski et al. of Poland, examines the role of ionic liquids as new electrolytes for carbon-based supercapacitors. Although not directly addressing the role of new carbon materials (the area of major focus of this book), this interesting theoretical work seeks to optimize electrolyte media, which is in contact with carbon electrodes. 

GENERAL PROPERTIES OF IONIC LIQUIDS AS ELECTROLYTES FOR CARBON-BASED DOUBLE LAYER CAPACITORS... 

The general aim of this work is to show the properties of activated carbon-ionic liquid interface (AC-IL) as well as performance of capacitors based on activated carbons as electrode materials and ionic liquids as electrolytes. 

Besides silicon, other materials have also been used in micro fuel cells. Cha et al. [79] made micro-FF channels on SU8 sheets—a photosensitive polymer that is flexible, easy to fabricate, thin, and cheaper than silicon wafers. On top of fhe flow channels, for both the anode and cathode, a paste of carbon black and PTFE is deposited in order to form the actual diffusion layers of the fuel cell. Mifrovski, Elliott, and Nuzzo [80] used a gas-permeable elastomer, such as poly(dimethylsiloxane) (PDMS), as a diffusion layer (with platinum electrodes embedded in it) for liquid-electrolyte-based micro-PEM fuel cells. 

Choquette et al. investigated the possibilities of using a series of substituted sulfamides as possible electrolyte solvents (Table 12). These compounds are polar but viscous liquids at ambient temperature, with viscosities and dielectric constants ranging between 3 and 5 mPa s and 30 and 60, respectively, depending on the alkyl substituents on amide nitrogens. The ion conductivities that could be achieved from the neat solutions of Lilm in these sulfamides are similar to that for BEG, that is, in the vicinity of 10 S cm Like BEG, it should be suitable as a polar cosolvent used in a mixed solvent system, though the less-than-satisfactory anodic stability of the sulfamide family might become a drawback that prevents their application as electrolyte solvents, because usually the polar components in an electrolyte system are responsible for the stabilization of the cathode material surface. As measured on a GC electrode, the oxidative decomposition of these compounds occurs around 4.3—4.6 V when 100 fik cm was used as the cutoff criterion, far below that for cyclic carbonate-based solvents. 

Lewandowski, A. and Galmski, M., General Properties Of Ionic Liquids As Electrolytes For Carbon-based Double Layer Capacitors, New Carbon Based Materials for Electrochemical Energy Storage Systems, Barsukov et al. (Eds), Springer, The Netherlands, 2006, 73-83. 

A solid-state solar cell was assembled with an ionic liquid—l-ethyl-3-methylimidazolium bis(trifluoromethanesulfone)amide (EMITFSA) containing 0.2 M lithium bis(trifluoromethanesulfone)amide and 0.2 M 4-tert-butylpyridine—as the electrolyte and Au or Pt sputtered film as the cathode.51,52 The in situ PEP of polypyrrole and PEDOT allows efficient hole transport between the ruthenium dye and the hole conducting polymer, which was facilitated by the improved electronic interaction of the HOMO of the ruthenium dye and the conduction band of the hole transport material. The best photovoltaic result ( 7p=0.62 %, 7SC=104 pA/cm2, FOC=0.716 V, and FF=0.78) was obtained from the ruthenium dye 5 with polypyrrole as the hole transport layer and the carbon-based counterelectrode under 10 mW/cm2 illumination. The use of carbon-based materials has improved the electric connectivity between the hole transport layer and the electrode.51... 

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