| All solid state lithium ion batteries?ASS LIBs?are considered to be one of the best candidate for next generations batteries due to their high safety and high energy density.Compares to traditional LIBs,the ASS LIBs can solve the safety issues of battery fundamentally.However,there are two primary challenges for ASS LIBs.One is how to seek for solid state electrolyte with high performance,especially with high Li+conductivity.Another is how to improve the interfacial issues between solid state electrolyte and electrodes.And the second question is key bottle restricting the development of ASS LIBs.Most of previous works were focused on coating on the surface of electrolyte and electrodes,or introducing inter-layer.These ways could not handle the interfacial problems whole fully,though reduced interfacial resistance at some extent.Therefore,the ASS LIBs worked terribly at ambient temperature.Besides,the system become more complicated owing to new layers.The way of in-situ preparing poly?ethoxylate trimethylol propane triacrylate?solid state electrolyte was adopted in this paper.The interfacial resistance between solid state electrolyte and cathode was reduced greatly which contributed to developing ASS LIBs with high performance at ambient temperature.Besides,the mechanical performance of composite solid electrolyte was enhanced by incorporating with inorganic ceramic LLZO.Specifically,the major research contents are described as follows:?1?The solid state polymer electrolyte?SPE?PA3-PEO was in situ prepared on the surface of cathode by UV-curing.Both mechanical and electrochemical performance were improved due to the cross-linking between PA3 and PEO.The PA3-PEO solid state electrolyte with best comprehensive performance was synthesized by adjusting to the proportion of PEO.And PA3-PEO SPE owned highest ionic conductivity 2.25×10-5 S cm-1 at ambient temperature when the proportion was30%.It proved that solid state electrolyte kept contact with cathode by S mapping.Compared to the way of non situ preparation,the interfacial resistance was reduced by69%.Moreover,the corresponding all solid state cell based on PA3-PEO?in situ?had82.2%capacity retention after 100 cycles with 0.1 C and owned 132.5 mAh g-1 with0.3 C at ambient temperature.?2?The effect of UV radiation polymerization monomer structure on the electrochemical performance of solid electrolytes was studied by the regulation of bridging groups of acrylate derivatives.Various characterization methods were used to compare electrochemical performance of PA2-PEO,PA3-PEO and PA4-PEO SPEs.Among of them,PA2-PEO SPE owned highest ionic conductivity and electrochemical window,3.6×10-5 S cm-1,4.75 V respectively.And the reason was mainly that A2had least amount of sidechains which made PA2-PEO SPE chains move fastest.Furthermore,PA2-PEO SPE owned lowest glass transition temperature?Tg?which resulted in smallest space resistance for Li ion transformation.?3?The composite solid state electrolytes?CSPEs?PA2-PEO-LLZO with both high ionic conductivity and good mechanical property were prepared by incorporating LLZO with PA2-PEO SPEs.It found that the ionic conductivity of CSPEs had a relation of bell curve with proportion of LLZO.And the CSPE had highest ionic conductivity 4.4×10-5 S cm-1 when the proportion was 10%.Compared to PA2-PEO SPE,the mechanical strength of PA2-PEO-LLZO CSPE increased from 0.5 to 3.5MPa and the electrochemical window increased from 4.5 V to 5.6 V.Besides,the interface between PA2-PEO SPE with lithium anode was also improved and the interfacial resistance reduced from 1250?to 300?. |
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