Lithium aqueous electrolyte-based

Fig. 7.1 Comparison of gravimetric and volumetric energy density of lithium secondary cells with aqueous electrolyte-based systems...

As shown in Figure 22.1b, the reaction products in a Li-air battery using a nonaqueous electrolyte are accumulated in the air electrode or cathode side instead of in the anode side. In this case, if the reaction product cannot be easily dissolved in the electrolyte, the air electrode will eventually be blocked, especially at higher discharge rates. For an aqueous electrolyte-based, lithium-air battery, although the LiOH discharge product is soluble, the solubility is limited to 5 rnolL therefore, the discharge capacity will be limited if precipitation is to be avoided. 

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. 

Primary and secondary lithium batteries using a nonaqueous electrolyte, exhibit higher energy density than aqueous electrolyte-based batteries due to the cell potential higher than 1.23 V, the thermodynamic limitation of water at 25 °C. The excellent performances of nonaqueous lithium batteries may meet the need for high power batteries in micro-devices, portable equipment, and even electrical vehicles. 

Initial development of ambient secondary lithium batteries was based on the primary lithium systems described in Chapter 4, consisting of a lithium metal negative, a non-aqueous lithium ion conducting electrolyte and a positive electrode material which could undergo a reversible electrochemical reaction with lithium ions ... 

Shembel EM, Maksyuta IM, Neduzhko LI, Belosokhov AI, Naumenko AF, Rozhkov VV. Influence of the composition of lithium-based alloys, non-aqueous electrolytes and cycling conditions on the anode properties. J Power Sources 1995 54 416-420. 

Koch et al. disclosed DEE-based electrolyte solution, 2.5 M LiAsFg in DEE/THF (9 1), which enables bright lithium deposits up to lOC/cm by plating. This non-aqueous electrolyte solution exhibits the best < ling efficiency (>98%)... 

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. 

Eurukawa and co-workers [81] state that PANI is an interesting material because it is not only an ECP but is also a good material to use as an electrode of a secondary battery with aqueous or non-aqueous electrolytes. PANI polymerised from aniline in an aqueous acid solution is converted to several forms with different electrical properties by acid/base treatments and oxidation/reduction. The as-polymerised form gives high electrical conductivity ( 5 S/cm). It becomes insulating when treated with an aqueous alkaline solution or is reduced electrochemically in an aqneons acid solution. Reduced-alkali-treated PANI is also insulating and is unstable in air its colour changes from white to blue upon exposure to air. PANI doped with electrolyte anions is obtained by electrochemical oxidation [82]. It was found in this work to be a new conductivity form (o = 5.8 S/cm). Recently, a secondary lithium battery with a reduced alkali pellet as the cathode, and non-aqueous electrolytes has been developed as a power source of memory back up and a maintenance-free power source combined with a solar battery. 

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]. 

Figure 15. Charge/discharge capacity of a Lii i[Mhi/3Nii/3Coi/3]o,902/graphite lithium-ion cell using a Li2Bi2p9H3 based non-aqueous electrolyte. The cell had a nominal capacity of 1.6 mAh, and was charged for 3.2 mAh for each cycle to apply about 100% overcharge on the cell. The current used for overcharge test was 0.5 mA (C/3).

Commercial lithium-ion batteries based on flammable non-aqueous electrolytes and layered oxides such as LiCo02 and LiNiosCoo202 are inherently unsafe. Thermal reactions in such cells can be triggered by the... 

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