Liquid Nonaqueous Electrolyte

Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries Kang Xu... 

Nonaqueous liquid electrolyte solutions may be divided into subgroups according to several criteria based on the differences among the various polar aprotic solvents. The first division can be between protic or polar aprotic nonaqueous solvents and nonpolar solvents. In polar aprotic and protic nonaqueous systems, conductivity is achieved by the dissolution of the electrolytes and the appropriate charge separation of the dissolved species, allowing for their free migration under the electrical field. In nonpolar systems the conductance mechanism may be more... 

Electrochemical windows of nonaqueous liquid electrolyte solutions and what determines them. 

Nowadays, the most prominent battery technology is based on lithium storage and employs a nonaqueous liquid electrolyte. Before we focus on these systems, we will address selected rechargeable systems based on other elements. 

For commercial double-layer capacitors using activated carbon electrodes, a nonaqueous solution such as 0.5 to 1 mol dm (=M) Et4NBp4 in propylene carbonate (PC) or an aqueous solution such as 3.7 to 4.5 M (30 35 wt%) H2SO4 is used. The advantages of the nonaqueous liquid electrolytes are as follows ... 

Based on these properties, the double-layer capacitor comprising from a pair of the activated carbon electrodes and the nonaqueous liquid electrolyte is the most favorable one from the viewpoint of energy density. Ionic liquids are a kind of nonaqueous liquid electrolytes. 

Solid electrolytes for lithium-ion batteries are expected to offer several advantages over traditional, nonaqueous liquid electrolytes. A solid electrolyte would give a longer shelf life, along with an enhancement in specific energy density. A solid electrolyte may also eliminate the need for a distinct separator material, such as the polypropylene or polyethylene microporous separators commonly used in contemporary liquid electrolyte-based batteries. Solid electrolytes are also desirable over liquid electrolytes in certain specialty applications where bulk lithium-ion batteries as weU as thin-film lithium-ion batteries are needed for primary and backup power supplies for systems, devices, and individual integrated circuit chips. 

Xu, K. 2004. Nonaqueous liquid electrolytes for lithium-based rechargeable batteries. Chemical Reviews 104 4303-4417. 

Microemulsions are composed of two mutually immiscible liquid phases, one spontaneously dispersed in the other with the assistance of one or more surfactants and cosurfactants. While microemulsions of two nonaqueous liquids are theoretically possible (e.g., fluorocarbon-hydrocarbon systems), almost all of the reported work is concerned with at least one aqueous phase. The systems may be water continuous (o/w) or oil continuous (w/o), the result being determined by the variables such as the surfactant systems employed, temperature, electrolyte levels, the chemical nature of the oil phase, and the relative ratios of the components. 

K. Xu, Chem. Rev. 2004, 104, 4303-4417. Nonaqueous liquid electrolytes for hthium-based... 

K. Xu, Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries, Chem. Rev. (Washington, DC, U. S.) 2004, 104,4303-4418. 

Primary lifhium cells use a lithium-metal anode and a nonaqueous electrolyte having a larger window than the 1.23 eV of an aqueous electrolyte. Both liquid and solid Li -ion electrolytes can be used. 

In a series of papers Hachisu. Kobayasi, and Kose (375-379) reviewed the literature and investigated the subject in further detail. The particles can form ordered arrays without being in actual contact. In these arrays particles are all the same size and other sizes are excluded. The phenomenon involves a phase transition when the concentration exceeds a certain volume fraction, usually 0.5 . 0.1, whereby a second more concentrated phase is formed within which the particles are in an ordered arrangment. This is known as the Kirkwood-Alder transition (380-382) and is a purely statistical effect that does not require an attractive potential for its explanation. It is inhibited when ionic repulsion forces exceed a low level. The transition can occur in suspensions in aqueous and nonaqueous liquids. In aqueous systems it will not occur even when the particles are very uniform, unless the system is low in electrolytes. 

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