Lithium-Metal Batteries

Secondary lithium-metal batteries which have a lithium-metal anode are attractive because their energy density is theoretically higher than that of lithium-ion batteries. Lithium-molybdenum disulfide batteries were the world s first secondary cylindrical lithium—metal batteries. However, the batteries were recalled in 1989 because of an overheating defect. Lithium-manganese dioxide batteries are the only secondary cylindrical lithium—metal batteries which are manufactured at present. Lithium-vanadium oxide batteries are being researched and developed. Furthermore, electrolytes, electrolyte additives and lithium surface treatments are being studied to improve safety and recharge-ability. 

One of the most important factors determining whether or not secondary lithium metal batteries become commercially viable is battery safety, which is affected many factors insufficient information is available about safety of practical secondary lithium metal batteries [91]. Vanadium compounds dissolve electrochemi-cally and are deposited on the lithium anode during charge-discharge cycle. The... 

Films on lithium play an important part in secondary lithium metal batteries. Electrolytes, electrolyte additives, and lithium surface treatments modify the lithium surface and change the morphology of the lithium and its current efficiency [93],... 

Various cyclic ethers are reported to be superior solvents for secondary lithium metal batteries. 1,3-Dioxolane [94, 95] and... 

LiAsF6 Used commonly in lithium metal batteries because of good cycle life predicated on beneficial film formed on lithium and high solution conductivity. 

The cell, and the electrode and cell reactions, for the lithium-metal battery are ... 

This section will provide a general description of the lithium-metal battery, especially with regard to the problems arising from the use of lithium metal, and introduce the lithium-polymer batteries as a reliable solution to problems deriving from the use of the lithium-metal electrode. The lithium-ion battery will then be taken up and particular emphasis will be given to the insertion electrode materials used in both the lithium-metal and the lithium-ion batteries. 

The substitution of the liquid electrolyte with the less reactive polymer electrolyte has led to lithium-polymer batteries, among the most likely to be commercialized for electric vehicles [89]. It must be stressed that the lithium-polymer battery is still a lithium-metal battery and not a lithium-ion one. Lithium-polymer batteries are solid-state, in that their electrolyte is a solid. A great safety advantage of this type of battery is that the electrolyte will not leak out if there is a rupture in the battery case. Furthermore, it can be assembled in any size and shape, allowing manufacturers considerable flexibility in cell design for electric vehicle or electronic equipment. 

The strategy of hybrid and gel electrolytes is very promising for lithium-ion batteries, but it seems less viable for lithium-metal batteries due to the reactivity of lithium metal with the encapsulated solvent. In fact, high conductivity is not the only parameter in selecting a successful polymer electrolyte for the development of lithium batteries a low interface resistance and a high interface stability over time are also required to assure good cyclability and long life. 

Aurbach, D., Zinigrad, E., Teller, H., and Dan, R, Factors which limit the cycle life of rechargeable lithium (metal) batteries, J. Electrochem. Soc., 147, 1274,... 

Byme N, Hewlett PC, MacFarlane DR et al (2005) The zwitterion effect in ionic liquids towards practical rechargeable lithium-metal batteries. Adv Mater 17 2497-2505... 

Gurevitch, I., Buonsanti, R., Teran, A. A., Gludovatz, B., Ritchie, R. 0., Cabana, J., et al. (2013). Nanocomposites of titanium dioxide and polystyrene-poly(ethylene oxide) block copolymer as solid-state electrol3Aes for lithium metal batteries, /. Eiectrochem.. Soc.. 160(9), A1611-A1617. 

The LUMO/HOMO relationship of solvents for 3-V hthium metal battery and 4-V LIB for anode and cathode additives is shown in Fig. 19.7. Solvents for a lithium metal battery - which are mostly ethers - should be stable against lithium metal anode and therefore their LUMO values should be high. The solvents - mainly cyclic and chain carbonates - for 4-V LIB have lower HOMO values, which means they are strong against oxidation. A modified version of the software was used for MO calculation, so the data for additives may differ from values from the usual commercial software. The relation between HOMO and LUMO values for first-generation additives (candidate for anode additives) and second-generation additives for candidate of cathode were calculated using the modified MO theory and are shown in Fig. 19.7. These calculations were used to SCTeen the candidates to identify additives. 

Fig. 19.7 Classification of solvents for lithium-metal battery, for 4-V LIB, for anode and cathode additives by the MO theory...

Table 1 Various rechargeable lithium metal battery systems developed...

Lithium-metal batteries exhibit a very flat discharge profile that ensures reliable device operation throughout the battery discharge, although the shape of the discharge curve can make it more difficult for some devices to reliably judge the remaining run time. 

Recent developments also include in situ NMR spectroscopy of lithium battery cycling [66] and electrophoretic PFG-NMR [67, 68]. In the li um battery study, a static solids probe contained a small lithium battery pouch cell that was connected to an external potentiostat by shielded wires. Monitoring the Li spectrum while cycling the battery sees a shoulder on the lithium metal resonance appear when dendritic lithium deposits form This unique approach allows the real-time, non-invasive monitoring of the performance of lithium metal batteries at a... 

Lane, G. H., Bayley, R M., Clare, B. R., Best, A. S., MacFarlane, D. R., Forsyth, M. and Hollenkanp, A. R, Ionic liquid electrolyte for lithium metal batteries physical, electrochemical, and interfacial studies of iV-methyl-lV-butylmorpholinium bis(fluorosulfonyl)iinide, J. Phys. Chem. C114, 21775-21785 (2010). 

TABLE 34.10 aassification of Rechargeable Lithium Metal Batteries (Ambient Temperature)... 

The different types of rechargeable lithium metal batteries operating at ambient temperature are classified in four categories (see Table 34.10). 

CHARACTERISTICS OF SPECIFIC RECHARGEABLE LITHIUM METAL BATTERIES... 

Watarai, A., Kubota, K., Yamagata, M. et al. (2008) A rechargeable lithium metal battery operating at intermediate temperatures using molten alkali bis(trifluoromethylsulfonyl)amide mixture as an electrolyte. J. Power Sources, 183, 724-729. 

Molten (Li,K,Cs)TFSA (TFSA bis(trifluoromethylsulfonyl)amide, Li K Cs = 20 10 70 in molar ratio) was selected as an electrolyte of a rechargeable lithium metal battery taking account of the melting temperature [1] and physical properties. The viscosity, conductivity, and electrochemical window of this salt mixture at 170 °C are 36.5 cP, 22.5 mS cm , and 5.0 V, respectively [2]. The transport number of the lithium ion is 0.15 at this temperature [3]. 

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