Font Size: a A A

Research Of Novel Free-standing Composite Electrolytes For All-solid-state Rechargeable Lithium Batteries

Posted on:2017-08-19Degree:MasterType:Thesis
Country:ChinaCandidate:Y R ZhaoFull Text:PDF
GTID:2311330503958611Subject:Environmental Science and Engineering
Abstract/Summary:PDF Full Text Request
Safety issues of lithium secondary batteries are of the most urgent concerns associated with further advances in next-generation high-energy batteries. In contrast to organic-based liquid electrolytes, solid polymer electrolytes(SPEs) are considered safe because of their non-flammability. In this paper, several kinds of free-standing composite electrolyte membranes with high ionic conductivity and good electrochemistry stability were papered through incorporation of sulfide electrolyte Li10GeP2S12(LGPS) and NASICON-type Li1.5Al0.5Ge1.5(PO4)3(LAGP)into polyethylene oxide(PEO) matrix, respectively.1. LGPS,a sulfide lithium superionic conductor with extra-high ionic conductivity and wide potential window, is incorporated into PEO matrix to fabricate composite SPE membranes. The LGPS microparticles, acting as active fillers incorporation into the PEO matrix, have a positive effect on the ionic conductivity, lithium ion transference number and electrochemical stabilities. The phase transition behaviors for electrolytes are characterized by DSC, and the possible reasons for their enhanced ionic conductivities are discussed. The lithium ion conductivities of as-prepared composite membranes are evaluated, and the optimal composite membrane exhibits a maximum ionic conductivity of 4.2910-4Scm-1 at 60 oC and an electrochemical window of 5.2V. And the LiFePO4/Li battery fabricated with this new SPE membrane exhibits fascinating cycle performance with high capacity retention(92.5% after 50 cycles at 60oC) and attractive rate capacities of 158, 148, 138 and 99 mAhg-1 at current rates of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 oC, respectively. It is demonstrated that this new composite SPE should be a promising electrolyte applied in solid state batteries based on lithium metal electrode.2. Three kinds of LAGP particles, prepared by different methods, are incorporated into PEO matrix, and the effects on performance of composite electrolytes were compared. Ionic conductivity, lithium ion transference numbers and phase behaviors were evaluated, and the composite membranes consisting with the LAGP particles containing lower content of glass and smaller size and exhibited the best performance. The lithium ion conductivity of optimum composition was 184% higher than that of PEO-based electrolyte, and the electrochemical window of that was enhanced to 5.3V. However, PEO-LAGP composite electrolyte exhibited higher interfacial impedance against lithium metal. To improve the interfacial compatibility, PEO-LGPS composite electrolyte was added to the interface against lithium metal electrode. As a consequence, not just the interfacial compatibility against lithium metal but cell performance was improved effectively.
Keywords/Search Tags:solid polymer electrolyte, all-solid-state lithium battery, active filler, sulfide lithium superionic conductor, NASICON-type structure
PDF Full Text Request
Related items