engleski

Thermal properties of PEO/NaAlg blend film complexed with LiBOB

Development of Li-ion battery (LIB) with solid- state polymer electrolyte (SPE) drew many scientists' attention as the challenge of finding the material that will fulfil all the necessary demands to be considered as SPE in LIB. One of the promising polymers for the polymer electrolyte is poly(ethylene oxide) (PEO). Its main advantage lies in the broad range of complexation with different salts and electron-rich ether group facilitating the salt dissociation [1]. However, its lower ionic conductivity at room temperature needs to be improved, and one way is to blend PEO with other polymers to enhance the ion migration by crystallinity reduction of PEO. A smaller amount of crystalline phase will favour faster ion transport through the amorphous phase, which would mean higher conductivity [2]. Sodium alginate (NaAlg) as polyelectrolyte with the possibility of forming hydrogen bonds between its hydroxyl groups and ether oxygen in PEO was proved to be a good choice for preparation of miscible blend with PEO that has an excellent film-forming ability and good thermal properties [3]. Lithium bis(oxalato)borate (LiBOB), as salt for the preparation of SPE, has its advantages, primarily as environmentally friendly salt with high thermal stability and bulky anion size [2]. This investigation is focused on the preparation of flexible and freestanding solid-state polymer electrolyte film based on PEO/NaAlg/LiBOB composite by solution cast technique. The aim was to prepare film with good thermal properties and thermal stability for solid-state lithium polymer batteries. First, the structural and morphological features of the casted polymer composite films have been investigated by using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). In addition, thermal properties and thermal stability were investigated by using differential scanning calorimetry (DSC) and thermogravimetry (TG). Investigation revealed changes in structure incorporating LiBOB salt in PEO/NaAlg blend film and variation of salt concentration. The addition of LiBOB salt has a complex effect on PEO thermal properties in PEO/NaAlg/LiBOB film, with a reduction in PEO crystallinity. PEO/NaAlg film degrades in three degradation stage, while PEO/NaAlg/LiBOB films have more complex degradation with up to eight degradation stages depending on the composite composition. The primary influence of the salt incorporation in PEO/NaAlg film is the reduction of the PEO degradation rate with the increase of LiBOB content. [1] A. Arya, A. L. Sharma, Macromolecular Research, 27 (2019) 334 [2] A. Arya, A. L. Sharma, Ionics, 23 (2017) 497 [3] S. Perinović Jozić, A. Sesar, Z. Grubač, B. Andričić, Kemija u industriji, 69 (2020) 503

polymer electrolyte, poly(ethylene-oxide), sodium alginate

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