THESIS
2022
1 online resource (x, 56 pages) : illustrations (some color)
Abstract
With merit to the ultra-high theoretical capacity of the metallic Li anode, lithium metal
batteries (LMBs) hold great promise as next-generation batteries to replace Li-ion batteries and
spearhead decarbonization efforts. However, safety concerns arise from the uncontrollable
dendrite growth and leakage of liquid electrolyte, which can be mitigated by replacement via a
solid-state electrolyte (SSE), or by creating an artificial solid-electrolyte interphase (SEI).
Herein, we demonstrate the ionic covalent organic frameworks, (iCOFs) or ionic porous
organic polymers, (iPOPs) can be designed for either strategy, using anionic silicate as a motif
for construction of the polymer frameworks. In the first project, the ionic covalent organic
framework AQ-SiCOF-Li was coated on metallic Li chip...[
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With merit to the ultra-high theoretical capacity of the metallic Li anode, lithium metal
batteries (LMBs) hold great promise as next-generation batteries to replace Li-ion batteries and
spearhead decarbonization efforts. However, safety concerns arise from the uncontrollable
dendrite growth and leakage of liquid electrolyte, which can be mitigated by replacement via a
solid-state electrolyte (SSE), or by creating an artificial solid-electrolyte interphase (SEI).
Herein, we demonstrate the ionic covalent organic frameworks, (iCOFs) or ionic porous
organic polymers, (iPOPs) can be designed for either strategy, using anionic silicate as a motif
for construction of the polymer frameworks. In the first project, the ionic covalent organic
framework AQ-SiCOF-Li was coated on metallic Li chip to form an artificial SEI layer. AQ-SiCOF-
Li, featuring both redox active anthraquinone linkers and anionic hexacoordinate
silicate nodes was coated on a metallic Li anode as a bifunctional SEI, exhibits an ion
conduction of 9.1 mS cm
–1 with transference number ?
??+ of 0.92. Full cells with AQ-SiCOF-Li
coated anodes exhibited an enhanced specific capacity of 200 mAh g
–1 at 0.2 C. Taken
together, AQ-SiCOF-Li demonstrates its versatile high performance as both electrode and
conductive interphase. In the second project, the porous polymer ionic SiPOP-Li, integrating
both silicate nodes and lithium sulphonate linkers was successfully mechanochemically synthesized, and demonstrated Li
+ conductivity of 5.9 × 10
-5 S cm
–1 without plasticizers or
solvents, competitive with all-solid-state iCOF electrolytes. By bypassing the normal
solvothermal route, SiPOP-Li also demonstrates the potential to be rapidly synthesized while
minimizing the use of solvents, enhancing its fabrication viability. All in all, the strategies
explored herein show huge potential for designed fast ion conductors with diverse ionic or
redox active moieties to enable Li metal batteries in the near future.
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