Lithium-sulfur battery system

The lilhium-Uiiouyl chluridc, or die lithium-sulfur dioxide, system is often used in a reserve battery configuration in which the electrolyle is slored in a sealed compartment which upon activation may be forced by a piston or inertial forces into the interelectrode space. Most applications for such batteries arc in mines and fuse applications in military ordnance. 

It was found in these studies that the lithium-sulfur cell system could meet many of the requirements needed to develop a high energy density battery system. Long-term cycling tests showed, however, that... 

Development of lithium ion batteries proved to be a power factor of technical advance. While at present such batteries form the base for portable electronics, in the near future, one could look forward to wide application of larger devices based on lithium ion batteries, including their application in electric transport and smart grids. However, many researchers at present have already started attempting to predict the further development of batteries that fundamentally differ from lithium ion batteries. One can identify three electrochemical systems against various possible new battery variants (i) lithium-air batteries, (ii) lithium-sulfur batteries, and (iii) sodium ion batteries. 

The theoretical energy density of a lithium-sulfur electrochemical system is 2500 Wh/kg or 2800 Wh/1, which makes it immensely attractive for the development of a chemical power source. This attractiveness is also enhanced by the ready availability and cheapness of sulfur and the absence of environmentally harmful components. And, indeed, attempts of developing a battery using this electrochemical system were made yet in the end of the 1960s of the previous century, at the rise of the studies of electrochemical lithium systems. It was suggested in the beginning to use the negative electrode made of metallic lithium and the positive one of elementary sulfur supported directly on the current collector. The characteristics of these first layouts were clearly unsatisfactory, partly, because sulfur is an insulator. Later, the positive electrode came to be made of a mixture of sulfur and a carbon material (carbon black). 

Winston is a Shenzen-based Chinese company producing lithium-yttrium and lithium-sulfur batteries. They offer cells with capacities between 40 and 3000 Ah. Moreover, they offer electric vehicles, energy storage systems and EV charge stations. 

A catalyst that can prevent polysulfide anions from precipitating as solids would be highly desirable. While a catalyst still remains to be discovered, several approaches, common in catalysis, have been employed to improve the cycling performance of lithium-sulfur batteries. For example, new electrolytes [18-21], protective films [22], solubiHzed sulfides [23], and new cathodes [24] have been developed. However, the performance results have either not been reported or have been found to be inadequate for practical applications. For example, a disordered mesoporous carbon-sulfur composite in conjunction with ionic liquid electrolytes has been fabricated. This system achieves high initial capacity that deteriorates rapidly [20]. 

Another approach is to use a lithium/sulfur cell with nonaqueous electrolyte systems. Rechargeable lithium batteries are being developed for portable power applications such as electric vehicles, partly because of their specific energy ranges 100-150 Wh kg (and... 

The lithium sulfur dioxide and the lithium thionyl chloride systems are specialty batteries. Both have liquid cathode reactants where the electrolyte solvent is the cathode-active material. Both use polymer-bonded carbon cathode constructions. The Li-S02 is a military battery, and the Li-SOCl2 system is used to power automatic meter readers and for down-hole oil well logging. The lithium primary battery market is estimated to be about 1.5 billion in 2007. 

High-density power sources can be obtained from lithium- and sodium-sulfur batteries. The sulfides present in these systems are M2S, M2S2, M2S4, and M2S5. 

Li/S02 Cells Lithium/sulfur dioxide cells (Li/SC>2) are perhaps one of the most advanced lithium battery systems. They belong to the soluble cathode cells category. Liquid SO2 is used as cathode a lithium foil is used as anode, and lithium bromide dissolved in acetonitrile is used as electrolyte. The active cathode material is held on an aluminum mesh with... 

Among high-temperature batteries, the lithium-iron sulfide systems are reasonably safe, although there are some hazards connected with the 450-500°C operating temperature. The sodium-sulfur-system impact failure hazards are primarily connected with the possibility of SO2 emissions, sodium oxide dust, and fires resulting from sodium exposure to moisture. 

T Tigh-performance lithium—sulfur secondary batteries are being devel-- oped for use in electric automobiles and for off-peak energy storage in electric utility systems. These applications impose severe performance requirements that cannot be met by present batteries. For the electric automobile, the battery must have a minimum specific energy of <— 200 W-hr/kg, a specific power of at least 200 W/kg, and a lifetime of 3-5 yrs. The projected performance requirements for a battery for off-peak energy storage are a maximum cost of 12-15/kW-hr, a specific power of /—50 W/kg, and a minimum lifetime of 5-10 yrs. 

The specific lithium content depends strongly on the battery type and chemistry. The net values range from 0.114 kg/kWh [21] to 1.38 kg/kWh [35] This lithium content could change significantly if future lithium battery systems such as lithium-sulfur or lithium-air reach wide use. This could be a sensitive parameter to be considered in future studies. 

Further investigation should consider more scenarios, with realistic and even unrealistic assumptions, to understand the potential risk of lithium shortage, also from different stakeholder perspectives. Since technologies like lithium-siir or lithium-sulfur come closer to real application, the effects of lithium demand and the recyclability of such battery systems should be analyzed as a sensitive parameter in a prospective manner. 

The oxyhalides, thionyl chloride (SOCI2) and sulfuryl chloride (SO2CI2), have been employed in lithium primary cells by themselves and with macro additives to improve performance. The basic technology was developed after the Li/sulfur dioxide system by the Eveready Battery Company (now Energizer), the... 

With knowledge of these requirements, developments have been carried through to improve the lead-acid, nickel/iron, and high-temperature lithium/sulfur systems to the above standards. Outstanding successes were made that can be regarded as milestones of battery development. The first lead battery systems as they were tested in MAN and Mercedes Benz buses, Volkswagen and Mercedes Benz vans, and other experimental vehicles should be mentioned here ... 

The present situation is made easier by the comparably low turnover of lithium batteries. Partly batteries are disposed of as harmless in normal sanitary landfills (like primary lithium/manganese dioxide cells), partly more active systems are brought to special landfills (like lithium/sulfur dioxide together with neutralizing amounts of limestone), and partly batteries are burned in special ovens in combination with oil (like lithium/thionylchloride batteries). 

The Jet Propulsion Laboratory (Pasadena, CA) has evaluated several types of lithium primary batteries to determine their ability to operate planetary probes at temperatures of -80°C and below. Individual cells were evaluated by discharge tests and Electrochemical Impedance Spectroscopy. Of the five types considered (Li/SOCl2, Li/S02, Li/Mn02, Li-BCX and Li-CFn), lithium-thionyl chloride and lithium-sulfur dioxide were found to provide the best performance at -SOT. Lowering the electrolyte salt to ca. 0.5 molar was found to improve performance with these systems at very low temperatures. In the case of D-size Li/ SOCI2 batteries, lowering the LiAlCl4 concentration from 1.5 to 0.5 molar led to a 60% increase in capacity on a baseline load of 118 ohms with periodic one-minute pulses at 5.1 ohms at -85 C. 

Figure 20.7 shows the major battery components prior to assembly. The components shown are fabricated primarily from 321 stainless steel, and the construction is accomplished with a series of TIG welds. The hardware shown is designed specifically for use with the lithium/ sulfur dioxide electrochemical system however, it is adaptable, with minor modifications to other liquid and solid oxidant systems. The battery can also be adapted to electrical rather than manu activation. 

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