Lithium Bis Trifluoromethanesulphonyl Imide Research Articles

Polypyrrole Actuator Operating Characteristicsin Electrolyte Solution Mixed with Methanol

In this work, a PPy actuator was fabricated by galvanostatic electropolymerization. The electrochemical deformation behaviors of the PPy actuator were investigated in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), containing different concentrations of methanol. Marked improvement of the actuating strain of approximately 9% was achieved when the actuator was driven by a potential between –1 and 1 V in the LiTFSI electrolyte containing 40 to 50% of methanol under a load stress of 0. 3 MPa. On the other hand, the actuator functioned in the electrolyte solutions containing more than 60% of methanol showed rapid decrease of the actuating strain and the electrochemical creep after repeated actuations. Possible mechanisms for these behaviors were discussed.

Behaviors of Polypyrrole Soft Actuators in LiTFSI or NaCl Electrolyte Solutions Containing Methanol

Organic soft linear actuators were fabricated using galvanostatic electropolymerization of the polypyrrole (PPy) thin film using a methyl benzoate electrolyte solution of N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide. The electrochemical deformation behaviors of the PPy actuators were investigated in aqueous solutions of an electrolyte, lithium bis (trifluoromethanesulphonyl) imide (LiTFSI) or sodium chloride (NaCl), containing different concentrations of methanol. The actuating strain of approximately 9% was achieved when the actuator was driven by a potential between –1 and 1 V with the potential sweep rate of 10 mV/s corresponding to 0.0025 Hz in the LiTFSI electrolyte containing 40% to 50% of methanol under a load stress of 0.3 MPa. However, the PPy actuator could not catch up with the higher frequency. On the other hand, the PPy actuator caught up with the potential sweep up to 0.1 Hz in the NaCl solutions with a methanol concentration between 40% and 60% with the expense of the actuating strain to approximately 1%.

Dynamic Behaviors of Polypyrrole Actuators in Electrolyte Solution Mixed with 2-Propanol

It has been previously reported that dynamic behaviours of polypyrrole (PPy) soft actuators were improved when they were driven in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) containing an optimised amount of 2-propanol. In this work, the influences of the potential sweep rate on electrochemical and creep strains of PPy actuators in aqueous LiTFSI electrolyte solutions with 2-propanol concentrations of 0 and 20% were investigated under the load stress of 0.3 MPa. The electrochemical strain rates in the 0% and 20% 2-propanol solution were found to be approximately 0.1% s−1 and 0.25% s−1, respectively, and they are nearly independent of the sweep rate between 10 and 25 mV s−1. These results suggest that TFSI anion penetration into the PPy films might be limited by the interactions between the PPy surface and the TFSI anions. The creep rate was more rapidly increased as time elapsed in the electrolyte solution containing 2-propanol than that in the electrolyte solution without 2-propanol, which was due to the swelling of PPy film in the electrolyte.

Comparison of Polypyrrole Organic Thin Film Actuators with or without Silicon Microspring

Organic actuators utilizing electrochemomechanical strain are of special interest for application in some types of microelectromechanical systems (MEMS). Amongst of those, polypyrrole (PPy) actuators have advantages of their large strain and stress. In this work, two kinds of PPy thin film actuators with or without a silicon MEMS microspring were fabricated and compared. The polypyrrole thin films with the thickness of 91 µm were deposited by galvanostatic electropolymerization. One of the actuators was inserted with a silicon MEMS microspring with the length of 15 mm, the width of 0.5 mm, and the thickness of 60 µm. The MEMS PPy actuator exhibited nearly 12% of the electrochemical strain under the load stress of 0.3 MPa in a water solution of an electrolyte, lithium bis-trifluoromethane sulphonyl imide (LiTFSI) at the bias sweeping rate of 10 mV/s in the voltage range between −1 and 1 V. Although the performances of the MEMS acstuators showed some degradation compared to the PPy actuator without the MEMS microspring, the MEMS PPy actuator may be beneficial to drive MEMS structures, which require a large strain and a large stress with a low voltage actuation.

Effect of 2-Propanol Concentration in Electrolyte Solution on Polypyrrole Actuator Performance

Organic soft linear actuators made of conducting polymers such as polypyrrole (PPy) films are of special interest for application in microelectromechanical systems (MEMS) because they generate large electrochemomechanical stress and strain. In this work, a PPy actuator was fabricated by galvanostatic electropolymerization. The electrochemical deformation behaviors of the PPy actuator were investigated in aqueous solutions of an electrolyte, lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), containing different concentrations of 2-propanol. Marked improvement of the electrochemical strain from 3 to 12% was achieved when the actuator was driven by a potential between -1 and 1 V in the LiTFSI electrolyte containing 20 to 40% of 2-propanol under a load stress of 0.3 MPa. Possible mechanisms for these behaviors were discussed.

Investigation of Li salt doped succinonitrile as potential solid electrolytes for lithium batteries

Solid ionic conductors with good conductivity at room temperature and mechanical flexibility are very attractive candidates for application as electrolytes for secondary lithium batteries. Plastic crystal electrolytes formed by doping succinonitrile with lithium salts can potentially meet these requirements. In this study, succinonitrile doped with various lithium salts were characterized by differential scanning calorimetry, powder X-ray diffraction, conductivity measurements and in electrochemical studies. The much better conductivities and electrochemical performance of certain lithium salts in comparison to the others studied has been found to be correlated to their propensity to form crystalline adducts with succinonitrile at low molar concentrations. Of the lithium salts studied, only two which did not form crystalline adducts at low concentrations: lithium bis-trifluoromethanesulphonylimide (Li[CF 3SO 2] 2N) and lithium tetrafluorborate (LiBF 4) had high enough conductivities at ambient temperature for evaluation in lithium cells. Contrary to prior predictions, both showed reasonable capacities, high coulombic efficiencies, and good capacity retention even with metallic lithium as the anode.

Plastic crystalline phases of crown ether:salt complexes and their utilization in lithium-metal batteries

We have shown that crown ether complexes with the lithium salt, lithium bis-(trifluoromethanesulphonyl) imide (LiTFSI), are plastic crystals as evidenced by DSC and their mechanical properties. The conductivity of the complexes was measured and found to vary as a function of crown ether:salt molar ratio. Our study of the (18-Crown-6)–LiTFSI (1/1) solid complex showed that it has a high conductivity reaching ∼10 −4 S cm −1 at 50 °C and an electrochemical stability of over 4 V enabling its use in a lithium-metal battery. A lithium battery with 1:1 (18-Crown-6)–LiTFSI as electrolyte was assembled, tested, and found to exhibit reversible Li + transport.