Charge LiTFSI/ electrolyte

These two effects were clearly seen in a study undertaken by Kara et al. [36]. In their work, PPy doped with bis(trifluoromethanesulfonyl)imide (TFSI) was actuated in various water/propylene carbonate (PC) solutions containing LiTFSI. The optimum performance of 23.6 % maximum strain at a strain rate of 10.8 % s was achieved within an actuation solution that consisted of 60 % water and 40 % PC. Improvements in both the strain rate and the maximum strain were seen with actuation in LiTFSI electrolytes of water/PC blended solvents over actuation in electrolytes of either water or PC alone. The improved actuation was attributed to the fact that a greater swelling occurred from the PC solvent (enabling a faster and easier ion transfer) and an improvement in the ionic conductivity from the water solvent (enabling a better charge transfer). As such, the optimised performance for this system was realised at 40 % PC. 

The mechanism of lithium transport was also studied in [pyri3][TFSI] + 0.25 LiTFSI [86]. The LL cation transport was found to occur primarily by exchanging TFSF anions in the first coordination shell of a LL with a smaller ( 30%) contribution also due to Li" cations diffusing together with their first coordination shell. It is important to note that despite high conductivity of IL-based electrolytes ( 10 S/cm) the hthium contribution to the charge transport remains quite low. 

Fig. 3 Potential profile from a galvanostatic discharge/charge cycle of a parallel-electrode, aptotic Li-02 battery with a porous carbon positive electrode, Li metal anode, and LiTFSI/DME electrolyte at a current of 0.2 mA/cm. Data courtesy of L. Griffith, Monroe Research Group...

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