O Department Of Alkaline Polymer Electrolyte Preparation And Performance. The Pva-ca-koh-h <sub> 2 </ Sub>

The development history, categories, basic features and their characterization techniques of solid polymer electrolytes(SPE) were discussed in this paper, and the models of ion transport and the new development status of alkaline SPE in recent years were also presented. On the basis of abundant literatures and experiment data, the effect of the blend ratio, fabrication techniques on electrochemical properties was investigated, the ion transport mechanism was elementary discussed for this PVA(Polyvinyl alcohol)-CA(Crylic acid)-KOH-H₂O system.Alkaline solid polymer electrolyte films composed of PVA-CA-KOH-H₂O series, were prepared by a solution-cast technique. The influences of alkali concentration, water content and CA on ionic conductivity and electrochemical stability were studied through orthogonal experiments and single factor experiments design, the relationship of structure and electrochemical properties is analyzed from the experiment data got from FIRT, XRD,DSC, AC impedance and CV test.The orthogonal experiments results indicate that the concentration of KOH affects the electrochemical properties most, then the content of CA, next the content of PVA, the stiring time comes last. The optimum scheme is that PVA:CA:KOH:H₂O=3:1.5:6:40.The ionic conductivity of SPE increased progressively up to a maximum of 0.1818S/cm when the KOH/PVA ratio was 3.3, then decreased with the alkali content. The electrochemical potential stability window did not change remarkably with KOH concentration, just around 3.6V. The temperature dependence of the ionic conductivity was agreed with Arrhenius equation. It means the ions in polymer matrix transport essentially through the crystal hollows.The analysis of polymer structure indicates that the non-crystalline phase is the majority and the crystalline phase is the minority: There is a definite interaction between additives and PVA, which not only reduces the crystallization degree of ASPE to enlarge amorphous areas but also improves the ability of segmental motion by destroying the well-regulated and orderly arrangement of polymer chain, meanwhile restricts the mobility of potassium cations and increases the anionic transference number of hydroxide ions, all of these improved the ionic conductivity. The ionic conductivity occurs essentially within the amorphous phase of the ASPE. CA was only blended in the PVA matrix, but it can absorb more water, so much more KOH can be soluted in the polymer, finally enhance the concentration of charge carriers. The ionic conductivity increases followed.The water content has remarkable influence on the ionic conductivity. When the content was less than 30wt%, the ionic conductivity increase quite slowly. But when the content exceeds 30wt%, the conducting phase can be formed more easily in the polymer system, so the ionic conductivity increased fast.