Liquid based electrolytes are known to have safety issues and for their low volumetric energy densities to meet the future energy storage demand. Solid electrolytes based on ion conducting solid ceramic and solid polymer electrolytes are being studied and considered as an alternative to alleviate the issues with liquid electrolytes. Their mechanical property to better suppress dendrite formation gives them an edge to be considered in the realization of high - capacity lithium metal batteries. However, each have such issues associated with them as low ionic conductivity in the case of polymer electrolytes and bad interfacial contact with the lithium anode in the case of inorganic ionic conducting solid electrolytes. Polymer – ceramic composite electrolytes are regarded as a promising option to take advantage of the merits of both and obtain a solid electrolyte which can conduct lithium ions as high as in the mS/cm scale with good electrode – electrolyte interfacial contact, a high electrochemical stability window and high lithium dendrite suppression. This work has aimed to tune the surface of the garnet type ceramic electrolyte, Li7La3Zr2O7, referred to as LLZO, by acid treatment to bring about a better conductivity and lithium – ion transference number of the composite it is applied to. The acid, oxalic acid in this work, treatment has produced the required surface groups, hydroxide ion and oxalate ion, which are hypothesised to help improve the conductivity through the beneficial interactions they bring into the matrix. The conductivity and transference number measurements have revealed the treatment of the LLZO with the acid to have a positive impact on the conductivity and lithium – ion transference number of the composite compared to the untreated counterpart. Typical of the results obtained are the increment in conductivity and the lithium-ion transference number of composites containing 50 % ceramic (LLZO) mass loading. Across all the temperatures the conductivity is measured, an increment by a range of 2.5 times (at room temperature) to 7.8 times (at 60 0C) was obtained. Similarly, the lithium-ion transference number has increased from 0.121 in the composite containing 50 % untreated (pristine) LLZO to 0.159 in the composite containing the same mass loading of oxalic acid treated LLZO.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-451859 |
| Date | January 2021 |
| Creators | Gebrehiwot, Dagmawi Befikadu |
| Publisher | Uppsala universitet, Strukturkemi, Uppsala universitet, Oorganisk kemi, Uppsala universitet, Fysikalisk kemi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPKEM E ; 94 |
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