Lithium nonaqueous electrolyte-based

Figure 9. Schematic illustrations of the surface film formed on lithium in nonaqueous electrolytes based on LiBp4 solutions and the subsequent reactions. (Reproduced with permission from ref 222 (Figure 12). Copyright 1995 The Electrochemical Society.)...

In nonaqueous electrolytes based on some organic solvents metallic lithium is stable and can be used as anodes in batteries. Lithium and other alkali metals have highly negative electrode potentials (see Table 1.1). Thus batteries with lithium anodes have much higher EMF and OCV values than batteries with aqueous electrolytes. 

B. G. Nolan, S. H. Strauss, J. Electrochem. Soc. 2003, 150, A1726-A1734. Nonaqueous lithium battery electrolytes based on bis(polyfluorodiolato)borates. 

Both nonaqueous and aqueous electrolyte-based Hthium-air batteries have similar theoretical specific energies ( 11000 Whkg based on Hthium alone), as shown in Table 22.1. Zheng et al. [39] simulated both aqueous and nonaqueous electrolyte-based Hthium-air batteries where the total weight of the Hthium, the carbon-based air electrode, and the electrolyte were considered. Their analysis showed that the maximum theoretical specific capacities of the cells are 435 and 940 mAh for lithium-air batteries with aqueous- and nonaqueous-based electrolytes, respectively. The main difference between these two kinds of Hthium-air batteries originates from the fact that the solvent is consumed in aqueous electrolyte-based lithium-air batteries, but it is not consumed in the nonaqueous electrolyte-based Hthium-air batteries. 

The organic nonaqueous electrolyte-based Li-air battery has gained a significant amount of attention. The catalytic reduction of oxygen is primarily a two-electron process leading to the formation of lithium peroxide (U2O2) and lithium oxide (IJ2O) as the final products [85,93,94], as expressed below ... 

Room-temperature molten salts are a relatively new subgroup of liquid nonaqueous electrolytes. They share their advantages and disadvantages. Unfortunately, until now, no useful room-temperature molten salt based on lithium cations has been available. 

The available choice of lithium salts for electrolyte application is rather limited when compared to the wide spectrum of aprotic organic compounds that could make possible electrolyte solvents. This difference could be more clearly reflected in a comprehensive report summarizing nonaqueous electrolytes developed for rechargeable lithium cells, in which Dahn and co-workers described over 150 electrolyte solvent compositions that were formulated based on 27 basic solvents but only 5 lithium salts. ... 

As a result, the acid strength of the proton is approximately equivalent to that of sulfuric acid in nonaqueous media. In view of the excellent miscibility of this anion with organic nonpolar materials, Armand et al. proposed using its lithium salt (later nicknamed lithium imide , or Lilm) in solid polymer electrolytes, based mainly on oligomeric or macro-molecular ethers. In no time, researchers adopted its use in liquid electrolytes as well, and initial results with the carbonaceous anode materials seemed promising. The commercialization of this new salt by 3M Corporation in the early 1990s sparked considerable hope that it might replace the poorly... 

All lithium based batteries use nonaqueous electrolytes because of the reactivity of lithium in aqueous solution and because of the electrolyte s stability at high voltage. The majority of these cells use microporous membranes made of polyolefins. In some cases, nonwovens made of polyolefins are either used alone or with microporous separators. This section will mainly focus on separators used in secondary lithium batteries followed by a brief summary of separators used in lithium primary batteries. 

A major part of the work with nonaqueous electrolyte solutions in modern electrochemistry relates to the field of batteries. Many important kinds of novel, high energy density batteries are based on highly reactive anodes, especially lithium, Li alloys, and lithiated carbons, in polar aprotic electrolyte systems. In fact, a great part of the literature related to nonaqueous electrolyte solutions which has appeared during the past two decades is connected to lithium batteries. These facts justify the dedication of a separate chapter in this book to the electrochemical behavior of active metal electrodes. 

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. 

The first rechargeable cells described in 198were based on a doped polyacetylene film serving as a positive electrode coupled with the negative lithium electrode in a nonaqueous electrolyte. Later versions included cells constructed of p- and n-doped polyacetylene films. Since then, several other systems have also been studied for potential battery applications. They include doped... 

Most of the liquid electrolytes used in the commercial lithium-ion cells are the nonaqueous solutions, in which roughly 1 mol (tar (= M) of lithium hexafluoro-phosphate (LiPF ) salt is dissolved in the mixture of carbonate solvents selected from cyclic carbonates - ethylene carbonate (EC), and propylene carbonate (PC) and linear carbonates - dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) -, whose chemical structures are displayed in Fig. 4.2. Recently, another type of liquid electrolyte based on 1.5 M LiBFyy-butyrolactone (GBL) + EC came onto the market for the laminated thin Uthium-ion ceUs with an excellent safety performance. Many other solvents and Uthium salts have limited appUcations, although much effort has been made to develop new materials. Into the above baseline electrolyte solutions, a small amount of the additives are dissolved, which are so-called functional electrolytes. ... 

Abraham and Jiang first reported a Li-air battery using a nonaqueous electrolyte at 1996 [1]. They suggested that lithium peroxide is a discharge product based on 2(Li -i- e ) -i- O2 —> Li202, which resulted in a theoretical voltage of 2.96 V. However, because of low oxygen solubility in a nonaqueous electrolyte, the reported... 

To achieve higher energy density and higher voltage operation than aqueous ECs utilizing the bromide system, nonaqueous electrolyte systems have also been proposed such as an ionic liquid electrolyte-based EC system [47] and lithium-ion capacitor system [48]. 

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