Redox shuttle additives

Redox shuttles based on aromatic species were also tested. Halpert et al. reported the use of tetracyano-ethylene and tetramethylphenylenediamine as shuttle additives to prevent overcharge in TiS2-based lithium cells and stated that the concept of these built-in overcharge prevention mechanisms was feasible. Richardson and Ross investigated a series of substituted aromatic or heterocyclic compounds as redox shuttle additives (Table 11) for polymer electrolytes that operated on a Li2Mn40g cathode at elevated temperatures (85 The redox potentials of these... 

Following Adachi et al., aromatic compounds with similar functionalities were proposed for polymer electrolytes as redox shuttle additives, which included bipyridyl and biphenyl carbonates and di-fluoroanisoles. All these additives could protect the cathode from overcharging in the vicinity of 4.1... 

In 1994, Sony Corporation discovered that aUcoxybenzenes, such as 1,3,5-trime-thoxybenzene (98), 2,6-dimethoxytoluene (99), and 3,4,5-trimethoxytoluene (100), can be used as additives in small quantities [112], These compounds are called redox shuttle additives as they suppress the increase in battery voltage by consuming electric cnrrent throngh a redox process. 

Buhrmester, C. Chen, J. Moshurchak, L. Jiang, J. Wang, R. Dahn, J. R. Studies of aromatic redox shuttle additives for liFeP04-based li-ion ceUs, J. Electrochem. Soc., 2005, 152, A2390-A2399. 

The simplest model, still capable of addressing different electronic states, is an isolated molecular species - be it neutral (as electrolyte solvent or a redox shuttle additive) or charged (like a lithium salt anion or an oxidized redox shuttle). This is by far the most common model employed for any strategy and method combination. 

Adachi, M. Tanaka, K. Sekai, K. Aromatic Compounds as Redox Shuttle Additives for 4 V Class Secondary Lithium Batteries, J. Electrochem. Soc. 1999,146, 1256—1261. 

Wang RL, Buhrmester C, Dahn JR (2006) Calculations of oxidation potentials of redox shuttle additives for Li-ion cells. J Electrochem Soc 153 A445... 

Adachi M, Tanaka K, Sekai K (1999) Aromatic compounds as redox shuttle additives for 4 V class secondary lithium batteries. J Electrochem Soc 146 1256... 

Lee D-Y, Lee H-S, Kim H-S, Sim H-Y, Seung D-Y (2002) Redox shuttle additives for chemical overcharge protection in lithium ion batteries. Korean J Chem Eng 19 645... 

There are several barriers on the road to successful implementation of redox shuttles in lithium-ion cells e.g., several suitable redox couples work only at high charging voltages, and this means that they actually do not respond to heat generation in batteries. Very few stable redox shuttles for high voltage cathodes have been reported so far, presumably due to their high reactivity. Eventually, the majority of redox shuttle additives fail, presumably due to decomposition of their radical cation forms. Increased electron deficiency makes radical cations more susceptible to nucleophilic attack, which may result in reactions with electrolyte components. 

L. Zhang, Z. Zhang and K. Amine, Ed. I. BeUiarouak, Redox Shuttle Additives for Lithimn-Ion Battery , Lithium Ion Batteries - New Developments, Publ. InTech, 173-188, 2012. 

Z. Zhang, L. Zhang, K. Amine, Polyether-functionahzed redox shuttle additives for hthium ion batteries, WO Patent 2011/149970 A2. 

Other organic redox shuttles based on aromatic compoimds with heteroatom substitutions include phenothiazine [18], triphenylamine [89], diarylamines with different substitutions [38], and 2-(pentafluorophenyl)-tetrafluoro-l,3,2-benzodi-oxaborole [29, 137]. Nitroxide radicals such as (2,2,6,6-Tetramethylpiperidin-l-yl) oxy (TEMPO) have been studied as a redox shuttle as well but showed inferior rate of charge transfer compared with DDB [90]. In addition, lithium borate cluster salts (Li2Bi2Fi2) have also been reported to be suitable redox shuttle additives for 4-V lithium ion chemistry (Chen et al. [26]). 

Buhrmester C, Chen J, Moshurchak L, Jiang JW, Wang RL, Dahn JR (2005) Studies of aromatic redox shuttle additives for LiFeP04-based li-ion cells. J Electrochem Soc 152 A2390-A2399. doi 10.1149/1.2098265... 

Zhang L, Zhang Z, Wu H, Amine K (2011) Novel redox shuttle additive fm high-voltage cathode materials. Energy Environ Sci 4 2858-2862. doi 10.1039/c0ee00733a... 

Buhrmester C, Moshurchak LM, Wang RL, Dahn JR (2006) The use of 2,2,6,6-tetramethylpiperinyl-oxides and derivatives for redox shuttle additives in li-ion cells. J Electrochem Soe 153 A1800-A1804. doi 10.1149/1.2221860... 

Recently, dihydrophenazine derivatives (N,N -bis-(2-hydroxypropyl) dihy-drophenazine, and NJ4 -diethyldihydrophenazine) have been studied as redox shuttle additives by Tran-Van et aL [63]. N,N -bis-(2-hydroxypropyl) dihydrophenazine in IM LiC104/PCyDME (1 1) showed a short first plateau at around 3 V followed by a much longer one at 3.8 V. However, Nd4 -diethyldihydro-phenazine did not work as a redox shuttle additive. 

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