This study deals with the membrane and interface electrical properties investigation by electrochemical impedance spectroscopy (EIS). The EIS is a powerful technique for characterizing electrical behavior of systems in which coupled electrical processes occur at different rates.A systematics tudy on the effect of solution concentration,temperature and velocity, on the electrical resistance of anion-and cation- exchange membranes (AEMs and CEMs) and their interfaces (electrical double layer and diffusion boundary layer), was carried out. At the best of our knowledge, for t he first time electrolyte concentrations up to 4 M were used for the study of membranes and interface by EIS. Moreover, Pulsed Gradient Spin Echo Nuclear Magnetic Resonance (PGSE-NMR)technique was used to measure the water self-diffusion coefficients in swelled membrane as a function of the solution concentration and temperature.These measurements gave additional important insights about the effect of the electrolyte solution and fixed charges concentration in membrane,on membrane microstructure and its transport and electrical properties. & 2014TheAuthors.PublishedbyElsevierB.V.ThisisanopenaccessarticleundertheCCBYThis study deals with the membrane and interface electrical properties investigation by electrochemical impedance spectroscopy (EIS)
25 September 2014 in The Journal of Physical Chemistry C
Autonomic self-healing (SH), namely, the ability to repair damages from mechanical stress spontaneously, is polarizing attention in the field of new-generation electrochemical devices. This property is highly attractive to enhance the durability of rechargeable Li-ion batteries (LIBs) or Na-ion batteries (SIBs), where high-performing anode active materials (silicon, phosphorus, etc.) are strongly affected by volume expansion and phase changes upon ion insertion. Here, we applied a SH strategy, based on the dynamic quadruple hydrogen bonding, to nanosized black phosphorus (BP) anodes for Na-ion cells. The goal is to overcome drastic capacity decay and short lifetime, resulting from mechanical damages induced by the volumetric expansion/contraction upon sodiation/desodiation. Specifically, we developed novel ureidopyrimidinone (UPy)-telechelic systems and related blends with poly(ethylene oxide) as novel and green binders alternative to the more conventional ones, such as polyacrylic acid and carboxymethylcellulose, which are typically used in SIBs. BP anodes show impressively improved (more than 6 times) capacity retention when employing the new SH polymeric blend. In particular, the SH electrode still works at a current density higher than 3.5 A g–1, whereas the standard BP electrode exhibits very poor performances already at current densities lower than 0.5 A g–1. This is the result of better adhesion, buffering properties, and spontaneous damage reparation.