Electrolytes in lithium-ion batteries

The most common solvents used in Li-ion batteries are the alkyl carbonates, EC, dimethyl carbonate (DMC), DEC, and combinations thereof. The solvents used today are thermodynamically unstable at the Li potential. Reactivity with electrolyte, in which Li-ion battery anodes form an SEI, has been well documented [52]. The thermal stability of organic solvents and salts is one of the challenging issues for Li-ion battery electrolytes. The flammability of Li-ion battery electrolytes is another issue that needs to be addressed. 

The most common lithium salt used for 4 V Li-ion batteries has been LiPFg, because of the large electrochemical window and good anodic stability, as well as high solubility. However, the chemical stability is poor, since P-F bonds are highly susceptible to hydrolysis by even trace amounts of moisture. The reaction products of HF and POF3 lead to unavoidable HF contamination ofits solutions [12]. 

The use of additives in commercial cells is highly proprietary, so it is difficult to determine which additives might be in widespread use. Many of the reports discuss materials flammability studies rather than tests on complete cells. While this is a 

The choice of electrode materials in li-polymer batteries is generally similar to that in li-ion batteries with hquid electrolytes, except where the electrochemical stability of the polymer used is less stable to oxidation (by the cathode) or reduction (by the anode). There are several versions of organic polymer electrolytes discussed in this section. Some of the polymers are tme soHd polymers without substantial amounts of additives or plasticizers, and others are gels with a large volume of liquid electrolyte (up to 70% by volume). 

The safety of cells with polymer electrolyte cells is strongly influenced by the type of polymer electrolyte. In general the trend of increasing safety will be inorganic glass or ceramic electrolytes true sohd polymers gelled electrolytes. 

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H. Yoshitake, Functional Electrolyte in Lithium Ion Batteries (in Japanese), M.Yoshio, A. Kozawa, Eds., Nikkan Kougyou Shinbunsha, Japein, 2000, pp. 73-82... 

Ghimire, P. Nakamura, H. Yoshio, M. Yoshitake, H. Abe, K., Suppression of electrochemical decomposition of electrolyte in lithium ion batteries using electrolyte containing vinyl group compounds, Electrochemistry, 2003, 71, 1084-1086. 

Zhang L, Lyons L, Newhouse J, Zhang Z, Straughan M, Chen Z, Amine K, Hamcas RJ, West R (2010) Synthesis and characterization of alkylsilane ethers with oligo(ethylene oxide) substituents for safe electrolytes in lithium-ion batteries. J Mater Chem 20 8224-8226. doi 10.1039/c0jm01596b... 

Other studies on the flame retardant applications of phosphazene derivatives include the use of cyclotriphosphazenes to improve the flame-retardant properties of epojy composites,using fluorinated phosphazene derivatives as non-flammable electrolytes in lithium ion batteries and utilizing phosphazenes as flame-retardant additives in curing polysiloxanes. °... 

For use as an electrolyte in lithium-ion batteries, the ionic conductivity of the IL is crucial. The ionic conductivity (a) of mosf ILs is in fhe range of 0.1-10 mS/cm, as shown in Table 9.7. The highest ionic conductivity determined so far is fhaf of fhe composite IL [EtMelm](HF)2 gF, which has an ionic conductivity at room temperature of 100 mS/cm. The ionic conductivity of most other l-ethyl-3-methyl-imidazolium-type ILs is of the order of 10 mS/cm, and that of ILs with pyrrolium, pyridinium, piperidinium, and aliphatic quaternary ammonium cations varies between 0.1 and 5 mS/cm. 

PAN has a wide electrochemical window of up to 4.5 V when used as the matrix for polymer electrolytes in lithium-ion batteries. However, its ionic conductivity is not high so that little research has been done on its all-solid polymer electrolytes. It is generally plasticized with organic electrolyte to form gel polymer electrolytes, which will be discussed in Section 11.2. 

Considering that the presence of labile proton does not prevent the use of PIL-based electrolytes in lithium-ion batteries, it was therefore possible to imagine the possibility of using more broadly the H-bond Donors as electrolytes replacing those based on alkylcarbonates. The successful introduction of DESs-based lithium salts is an illustration of this new way of research into electrolytes replacing conventional organic solvents. 

Prasanth, R., Shubha, N., Hng, H.H., Srinivasan, M., Effect of nano-clay on ionic conductivity and electrochemical properties of poly(vinylidene fluoride) based nanocomposite porous polymer membranes and their application as polymer electrolyte in lithium ion batteries, Eur. Polym. J., 2013,49, 307-318. 

Lewandowski A, Swiderska-Mocek A (2009) Ionic liquids as electrolytes in lithium-ion batteries - an overview of electrochemical studies. J Power Some 194 601-609... 

Korepp C, Santner HJ, Fujii T, Ue M, Besenhard JO, Moller KC, Winter M (2006) 2-Cyanofuran - a novel vinylene electrolyte additive for PC-based electrolytes in lithium-ion batteries. J Power Some 158 578-582... 

Ionic liquids have attracted a lot of interest as potential alternatives to conventional carbonate electrolytes in lithium-ion batteries. Major advantages of ILs are due to their intrinsic physical properties, such as low vapor pressure, non-flammability, high ionic conductivity and unlimited combinations of cations and anions. Zhang and co-workers ... 

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