Ion Conductive Characteristics of Alkylborane Type and Boric Ester Type Polymer Electrolytes Derived from Mesitylborane

Abstract

Alkylborane type and boric ester type polymer electrolytes bearing mesitylboron units were prepared by hydroboration polymerization or dehydrocoupling polymerization using mesitylborane. The obtained well-defined organoboron polymer electrolytes showed ionic conductivities of 3.05 × 10 -5 -5.22 × 10 -6 S/cm at 50 °C in the presence of various lithium salts. The maximum conductivity was observed when LiTFSI was doped to boric ester type polymers. The lithium ion transference number was calculated to be 0.35-0.50, indicating a significant anion trapping effect of the organoboron unit. The alkylborane type polymer exhibited a higher lithium ion transference number due to stronger Lewis acidity of the alkylborane unit. The organoboron polymer electrolytes were subjected to polymer reaction with organolithium reagents in aim of immobilizing the anion to the polymer chain as borate anion. After the reaction with phenyllithium, ionic conductivities of 9.45 × 10 -7 -8.22 × 10 -7 S/cm were observed with a lithium ion transference number of 0.78-0.82. When pentafluorophenyllithium or naphthyllithium was employed as an organolithium reagent, the conductivity increased by 1 order of magnitude due to the improved dissociation degree of the lithium borate unit in the presence of electron-withdrawing substituent.

Poly(ethylene oxide)-based electrolytes for lithium-ion batteries

“…578 As discussed in Section 4.1.1, linear PEO copolymer containing single-ion group will be a good candidate for the preparation of polymer electrolytes owing to the good and tunable properties of BCPs. Ohno et al 579,580 synthesized linear organoboron polymer electrolytes composed of alternating oligoethylene oxide and organoboron units (P(EO-OB)-Li). The lithium transference number of 0.82 was obtained, which was much larger than those for salt-doped systems.…”

Synthesis and ionic conductivity of mixed substituted polysiloxanes with oligoethyleneoxy and cyclic carbonate substituents

“…However, PEOLiX complexes exhibit very low ambient conductivity, typically 10 −7 S/cm. Recently, several classes of polymer electrolytes based on comb polyphosphazene [17][18][19][20][21][22][23][24][25], polysiloxane [26][27][28][29][30][31][32][33][34][35] and borane containing polyethers [36] were found to exhibit higher ambient ionic conductivity. These results demonstrated that apWe dedicate this paper to Professor Dick Jones, polysilane pioneer and valued friend.…”

Enhanced Ionic Conduction in Organoboron Ion Gels Facilely Designed via Condensation of Cellulose with Boric Acids in Ionic Liquids

“…23,24 This concept was extended to solid polymer electrolytes by several research groups. [25][26][27][28][29] Incorporation of organoboron unit into polymer electrolyte resulted in improved lithium transference number of the matrix. The anion trapping of boron atom worked much efficiently in IL matrix than was observed in polyether systems.…”

“…30 Incorporation of several highly dissociable organoborate lithium salt structures into electrolyte matrix was particularly found to be effective to improve ionic conductivity. 28,29,[31][32][33][34][35] For instance, a zwitterionic molten salt 32 bearing lithium pentafluorophenylborate structure showed very high ionic conductivity as a zwitterionic molten salt.…”