Electrolytes polyacrylonitrile

The interfacial properties of gel electrolytes containing ethylene carbonate immobilized in a polyacrylonitrile (PAN) matrix with a lithium (bis)trifluoromethane sulfonimide (LiTFSI) salt have been studied 1139]. SEI stability appeared to be strongly dependent on the LiTFSI concentration. A minimum value of / SE1 of about 1000 Qcm2 was obtained after 200h... 

Figure 1. Temperature variation of the conductivity for a cross-section of polymer electrolytes. PESc, poly (ethylene succinate) PEO, polyethylene oxide) PPO, polypropylene oxide) PEI, poly(ethyleneimine) MEEP, poly(methoxyethoxy-ethoxyphosphazene) aPEO, amorphous methoxy-linked PEO PAN, polyacrylonitrile PC, propylene carbonate EC, ethylene carbonate.

Wang et al. [96] constructed a Na/S battery with a sodium metal anode, liquid electrolyte, and a sulfur (dispersed in polyacrylonitrile) composite cathode and tested its electrochemical characteristics at room temperature. The charge/discharge curves indicated that sodium could reversibly react with the composite cathode at room temperature. Average charge and discharge voltage was 1.8 and 1.4 V, respectively. Similar to lithium batteries, dendrite formation was noted as a critical problem for these cells. 

More recent methods proposed by Motorola and Mitsubishi Electric researchers differ in implementation details, but they share a common feature in that a separate adhesive layer (PVdF) is applied to the separator and used to bond the electrode and the separator films, using in the first case the hot, liquid electrolyte as an in situ PVdF plasticizer. Recently, Sony ° researchers described the use of a thin, liquid electrolyte-plasticized polyacrylonitrile... 

In hemodialysis, blood from the patient flows on one side of a membrane and a specially prepared dialysis solution is fed to the other side. Waste material in the blood such as urea, excess acids, and electrolytes diffuse into the dialysate the blood is then returned to the patient, as shown in Fig. 48. A patient typically undergoes dialysis three times per week in sessions lasting several hours each. Modern dialysis systems combine sophisticated monitoring and control functions to ensure safe operation. Regenerated cellulose was the first material used in hemodialysis membranes because of its biocompatibility and low cost it remains the most popular choice. Subsequently, high-permeability dialysis membranes derived from cellulose esters, modified polysulfone, or polyacrylonitrile copolymers have also gained wide acceptance because of the shorter sessions they make possible. 

However, it seems likely that a conductivity value of 10 S cm at room temperature is a goal that can only be achieved with polymer networks including organic solvents as plasticizers [96] or with polymer matrixes like polyacrylonitrile [97] or poly(methyl methacrylate) [98] entrapping a large amount of organic electrolytic solution, i.e., with hybrid and/or gel electrolytes. These electrolytes combine the advantage of the polymer s mechanical properties with the electrochemical properties of the liquid electrolytes. 

However, it is also possible to cycle CM made from pyrolyzed polyacrylonitrile in aqueous electrolytes, according to Beck and Zahedi [378]. Figure 30 shows relatively flat redox peaks around the quinone/hydroquinone center (f/s — 0 V, about 0.7 V vs. SHE). Protons are the counterions in this case. A polyquinonimine structure is concluded from (electro)chemical and FTIR data (cf. Fig. 34). These acceptor-type compounds have relatively high specific capacities of about 300 Ah/kg in the steady state. The initial capacities are even higher. It should be mentioned that graphite nanotubules were synthesized in the nanopores of a porous AI2O3 matrix at 250/ 600 °C [433]. 

Polymer gels based on polymers such as poly(vinylidene fluoride), polyacrylonitrile, and aprotic solvents containing added alkali metal salts, gave appreciable room-temperature conductivity. However, solvent volatility and voltage stability of the electrolyte were serious problems. 

Hwang, I Liu, H., 2002. Influence of organophilic clay on the morphology, plasticizer-maintaining ability, dimensional stability, and electrochemical properties of gel polyacrylonitrile (PAN) nanocomposite electrolytes. Macromolecules 35,7314-7319. 

Wang, C. H., H. C. Hsu, and J. H. Hu. 2014. High-energy asymmetric supercapacitor based on petal-shaped Mn02 nanosheet and carbon nanotube-embedded polyacrylonitrile-based carbon nanofiber working at 2 V in aqueous neutral electrolyte. Journal of Power Sources 249 1-8. 

Pandey, G. P., A. C. Rastogi, and C. R. Westgate. 2013. Polyacrylonitrile and 1-ethyl-3-methyliniidazolium thiocyanate based gel polymer electrolyte for solid-state supercapacitors with graphene electrodes. Electrochemical Capacitors 50 145-151. 

Tamilarasan, R, and S. Ramaprabhu. 2013. Graphene based all-solid-state supercapacitors with ionic liquid incorporated polyacrylonitrile electrolyte. Energy 51 374-381. 

Wang Z Huang B Xue R Huang X Chen L, Spectroscopic investigation of interactions among components and ion transport mechanism in polyacrylonitrile based electrolytes. 

Lu et al. [Ill] later reported on the development of solid-state electrochemical linear actuators with a polyaniline yarn-in-hollow fiber configuration using an ionic liquid electrolyte. These yarn-in-hollow fiber actuators, which were constructed using a triflic acid-doped polyaniline solid fiber inserted into a triflic acid-doped polyaniline hollow liber. A porous polyacrylonitrile insert separated the two electrodes, which contained the [BMIM] [Bp4] electrolyte (Figure 2.27). It was demonstrated... 

FIGURE 2.27 SEM image of yam-in-fiber electrochemical linear actuator fabricated by threading eight polyaniline yarns into a polyaniline hollow counterelectrode with a porous polyacrylonitrile separator inserted between the two electrodes containing the ionic liquid electrolyte. 

The well-known fact that the rate of electrochemical reactions is proportional to the surface area of the electrode makes ICP electrospun fibers ideal candidates as electrode materials in other small electrochemical devices such as supercapacitors and batteries. The small diameter of the fibers makes it possible for ions to rapidly diffuse between the center of the fiber and the surrounding electrolyte, which should lead to enhanced performance of electrochemical devices constructed from these electrospun fibers. Although no energy storage devices have so far been fabricated that utilize ICP electrospun fiber electrodes, there have been reports of using graphitized polyacrylonitrile electrospun fibers as the electrode material for fabricating carbon-based supercapacitors [186]. 

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