Solid, thin, and flexible energy storage devices are required to power flexible and wearable technologies which are rapidly growing in importance. One of the key components for solid-state energy storage is a polymer electrolyte which eliminates liquid electrolyte leakage and minimizes bulky packaging. An ideal polymer electrolyte for supercapacitors should exhibit the following properties: (a) high ionic conductivity; (b) a wide electrochemical stability window for maximum cell voltage; and (c) high environmental and temperature stability for device safety and long service life^[1-3].

In this paper, the novel, low-cost alkaline anion-exchange membranes (CS/PDDA), made from Chitosan and poly(diallyldimethylammonium chloride) blends, are successfully synthesized by a combined thermal and chemical cross-linking technique. The hydroxide conductivity (OH^-), water uptake, ion exchange capacity (IEC), thermal stability, oxidative stability and alkaline stability of CS/PDDA membranes are measured to evaluate their applicability in electrochemical capacitors. The effects of membrane composition on OH^- conductivity are studied using AC impedance technique. It is found that by cross-linking modifications, the membranes exhibit high OH^- conductivity of 0.0162S cm^-1 is achieved at m (CS) : m (PDDA)=1:0.5. The CS/PDDA membranes as electrode materials for supercapacitor demonstrated a wide voltage window (1.5 V), and exhibit high specific capacitance of 27.6 mF cm^-2 at 100 mV s^-1.

References

[1] H. Gao, K. Lian, RSC Advances, 4,33091(2014) .

[2] H. Gao, J. Li, K. Lian, RSC Advances, 4,21332(2014).

[3] M. Kaempgen, C.K. Chan, J. Ma, Y. Cui, G. Gruner, Nano Letters, 9,1872(2009).