Page 233 - Handbook of Battery Materials

202 7 Bromine-Storage Materials

Table 7.2 Complexation of Br 2 with quaternary ammonium salts.

Substance class Examples and references

–
Aliphatic Me 2 Et 2 N Br [47, 48], MeEt 3 N Br [47, 48]
+
−
+
–
−
Me 2 EtPrN Br [47, 48], Me 2 Et 2 PrN Br [47–49]
+
+
–
Et 3 PrN Br [48]
+
+
Bu 4 N Br [14, 33, 45, 49–51]
–
Et 4 N Br [14, 45, 49, 52, 53], Et 4 N C1 [14, 53]
+
+
–
+
Me 4 N Br [45, 49, 51, 54–56]
–
+
Oct 4 N Br [45]
+
Me 3 EtN Br [48, 57], Me 3 PrN Br [48]
+
–
MeEt 2 CMN Br [47]
+
–
+
+
Me 3 CMN Br [48], Et 3 CMN Br [48]
−
–
Me 2 EtCMN Br [48], MeEt 2 CMN Br [48]
+
−
+
–
+
Oct 3 MeN Cl [56] (isoamyl) 3 NHCl [50]
Me 3 NHBr [50, 58], Me 3 NHCl [50]
NH Br [59]
+
−
4
–
–
+
+
Et 3 hexadecN Br [60], Me 2 hexadec 2 N Br [60]
–
Me 2 dodec-2-hydoxy-EtN Br [60]
+
+
Aromatic Et 3 PhN Br [53, 60]
–
Me 3 PhN Br [51, 61, 62]
+
–
+
Heterocyclic Benzyldimethyl-(3-isobutoxy-2-hydroxy propy1)-N Br [60]
N-Methyl-N-ethyl pyrrolidinium bromide (MEP) [3, 14, 47–49, 63–72]
N-Methyl-N-ethyl morpholinium bromide (MEM) [3, 14, 47–49, 53, 56,
63–73]
N-Chloromethyl-N-methyl pyrrolidinium bromide (C-MEP) [47, 48, 73]
N-Chloromethyl-N-methyl morpholidinium bromide (C-MEM) [48]
2-Bromo-cyclohexylpyridinium bromide [53, 60, 63, 74]
2-Chloro-cyclohexylpyridinium bromide [53, 60]
N-Bromo-t-butyl pyridinium bromide [60]
N-Methoxymethyl-N-methyl piperidinium bromide [73]
–
Tenside-like [PhCH 2 NMe 2 (CH 2 ) 6 NMe 2 CH 2 Ph] 2Br [53, 60]
2+
–
[C 16 H 33 NMe 2 (CH 2 ) 4 NMe 2 C 16 H 33 ] 2Br [60]
2+
−
[C l2 H 25 NMe 2 (C 2 H 4 O) 3 H] Cl [53]
◦
temperature range (0–50 C), which is required for successful operation of flow
batteries. No single compound was able to fulfill this demand. From tests of various
ratios of MEP, MEM, and aliphatic ammonium bromides at 0, 50, and 100% state of
charge (SOC) and different temperatures, mixtures of MEP and MEM were found
to be particularly useful for bromine storage. The highly efficient potential of MEP
for reducing the concentration of free Br 2 in the aqueous phase was pointed out.
This fact was also mentioned by Bellows et al. [76] in their study of possibilities
for improving the battery electrolyte. Table 7.3 [48] illustrates the results of
that work.
Kawahara [64] studied the influence of the molar ratio MEP:MEM on the rate
of self-discharge in model batteries. This effect is strongly enhanced by high