Gel lithium ion batteries

Polymer lithium-ion batteries, or strictly called gel lithium-ion batteries, were first disclosed by the former Bellcore Company. However, the initial process had a low qualification rate, and the large-scale production cost was too high. In 1999, mass production started. The detail assembly process depends on the manufacturer. 

The former concept of polymer lithium-ion batteries is not appropriate, since the traditional separators such as polypropylene and polyethylene are also polymers. When polyvinylidene fluoride and other polymers are used, the organic electrolyte is entrapped in the porous structure to form a gel. Similar to lead acid rechargeable batteries, a gel battery is produced by fixing the sulfuric acid aqueous solution in the form of a gel. To avoid confusing the consumers, the concept "gel lithium-ion battery (GOB)" is used here instead of "polymer lithium-ion battery."... 

As discussed in Chapter 14, gel lithium-ion batteries have several clear advantages over traditional lithium-ion batteries, such as the following ... 

However, initially, the electrochemical performance of gel lithium-ion batteries was not so good, and they reached the present performance level... 

These types of separators consist of a solid matrix and a liquid phase, which is retained in the microporous structure by capillary forces. To be effective for batteries, the liquid in the microporous separator, which generally contains an organic phase, must be insoluble in the electrolyte, chemically stable, and still provide adequate ionic conductivity. Several types of polymers, such as polypropylene, polysulfone, poly(tetrafluoroethylene), and cellulose acetate, have been used for porous substrates for supported-liquid membranes. The PVdF coated polyolefin-based microporous membranes used in gel—polymer lithium-ion battery fall into this category. Gel polymer... 

The solid polymer electrolyte approach provides enhanced safety, but the poor ambient temperature conductivity excludes their use for battery applications. which require good ambient temperature performance. In contrast, the liquid lithium-ion technology provides better performance over a wider temperature range, but electrolyte leakage remains a constant risk. Midway between the solid polymer electrolyte and the liquid electrolyte is the hybrid polymer electrolyte concept leading to the so-called gel polymer lithium-ion batteries. Gel electrolyte is a two-component system, viz., a polymer matrix... 

Gel polymer lithium-ion batteries replace the conventional liquid electrolytes with an advanced polymer electrolyte membrane. These cells can be packed in lightweight plastic packages as they do not have any free electrolytes and they can be fabricated in any desired shape and size. They are now increasingly becoming an alternative to liquid-electrolyte lithium-ion batteries, and several battery manufacturers. such as Sanyo. Sony, and Panasonic have started commercial production.Song et al. have recently reviewed the present state of gel-type polymer electrolyte technology for lithium-ion batteries. They focused on four plasticized systems, which have received particular attention from a practical viewpoint, i.e.. poly(ethylene oxide) (PEO). poly (acrylonitrile) (PAN). ° poly (methyl methacrylate) (PMMA). - and poly(vinylidene fluoride) (PVdF) based electrolytes. ... 

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. 

Finally, the use of various synthetic routes, including the sol-gel process [122], rheological phase [123], predpitation/decomposition [124], hydrothermal [125] sonochemical [126] and combustion reactions [121], are all currently being widely investigated for the production of nanoionic materials for use in lithium ion batteries. 

Saunier, AUoin, E, Sanchez, J.-Y., Maniguet, L, 2004. Plasticized microporous PVdF separators for lithium ions batteries. Part 111 gel properties and irreversible modifications of PolyfvinyUdene fluoride) membranes under swelling in liquid electrolyte. J. Polym. Sci. Part B 42,2308-2317. 

Wang, S.-H., Kuo, P.-L., Hsieh, C.-T., Teng, H., 2014c. Design of poly(acrylonitrile)-based gel electrolytes for high-performance lithium ion batteries. ACS Appl. Mater. Interfaces 6,19360-19370. 

On the other hand, the high conductivity of the gel electrolytes may be exploited in an effective way by directing them to the development of new-design, plastic-like batteries where the lithium metal anode is replaced by a lithium-accepting compound, such as a carbon or graphite [75]. These are the so-called rocking chair or, more commonly lithium-ion batteries [76]. Basically, these batteries operate on the cyclic transport of lithium ions from one lithium-... 

Alternative routes to obtain lithium-ion plastic batteries have considered the use of PAN-based gel-type polymer electrolytes as separators. These electrolyte membranes, although macroscopically solid, contain in their structure the active liquid electrolyte (Figure 7.7). Therefore, they have a configuration which in principle allows a single lamination process for the fabrication of the lithium-ion battery, i.e., a process that avoids intermediate liquid extraction-soaking activation steps. 

The feasibility of the gel electrolytes for lithium-ion batteries development has been tested by first examining their compatibility with appropriate electrode materials, i.e., the carbonaceous anode and the lithium metal oxide cathode. This has been carried out by examining the characteristics of the lithium intercalation-deintercalation processes in the electrode materials using cells based on the given polymer as the electrolyte and lithium metal as the counter electrode. 

Once the compatibility of the gel-type electrolyte with both anode and cathode materials is ascertained, one can proceed with the combination of the two for the fabrication of polymer-based lithium-ion battery prototypes. A few examples of these prototypes have been reported at the laboratory level scale. One is provided by a battery of the type C/ LiC104-EC-PC-PAN/LiCryMn2.y04. 

A typical charge-discharge cycle is shown in Figure 7.14, and confirms the feasibility of the PAN-based gel electrolytes as separators in lithium-ion batteries by showing that the cell can indeed be cycled with a good capacity delivery. 

The separator should form a good interface with the electrodes to provide sufficient electrolyte flow. In addition to the above properties, the separator must be essentially free of any type of defects (pinholes, gels, wrinkles, contaminants, etc.). All of the above properties have to be optimized before a membrane qualifies as a separator for a Li-Ion battery. The general requirements for Lithium-Ion battery separators are summarized in Table 20.5. 

Recent demands of the market is for the mid- or large-sized lithium battery for the power-assisted bicycle, electronic bike, and hybrid vehicle. As the capacity of the battery increases, safety becomes very important. The gel polymer electrolyte contributes to keeping the battery safe even as the capacity of the lithium-ion battery increases. 

V. Aravindan, P. Vickraman, Solid State Sci. 2007,9,1069-1073. A novel gel electrolyte with lithium difluoro(oxalato)borate salt and Sb203 nanoparticles for lithium ion batteries. 

Section 2.4 reviews organophosphorous compounds as nonflammable or flame-retardant electrolytes for lithium-ion batteries. These include organic phosphates, phosphites, phosphonates, or phosphazenes, and a phosphonamidate as co-solvents or additives. The author introduces polymeric gel electrolytes containing these flame-retardant components. 

Yoshimoto, N. Goto, D. Egashira, M. Morita, M., Alkylphosphate-based nonflammable gel electrolyte for LiMn204 positive electrode in lithium-ion battery, J. Power Sources 2008,185, 1425-1428. 

Hao Y, Lai Q, Xu Z, Liu X, Ji X (2005) Synthesis by TEA sol-gel method and electrochemical properties of Li4Ti50i2 anode material for lithium-ion battery. Solid State Ionics 176 1201... 

G.B. Appetecchi, F. Alessandrini, S. Passerini, G. C ticcio, B. Boutevin, F. Guida-RetraSanta, Novel polymeric systems for lithium ion batteries gel electrolytes II. Hybrid cross-linked poly (fluorosilicone-ethyleneoxide), Electro-chimica Acta 50 (22) (2005) 4396-4404. 

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