Regulating Lithium-Ion Transference Number of a Poly(vinyl alcohol)-Based Gel Electrolyte by the Incorporation of H₃BO₃ as an Anion Trapper

Abstract

Gel electrolytes hold great promise for improving the safety of lithium-ion batteries (LIBs); however, their low lithium-ion transference number (t Li + < 0.4) remains to be improved. Herein, boron-containing poly­(vinyl alcohol) (B-PVA) solutions are prepared based on the simple reaction between PVA and H3BO3 and then electrospun to obtain the B-PVA nanofiber matrices. The gel electrolytes are formed by loading the liquid electrolytes into the as-obtained porous B-PVA matrices. We demonstrate that the t Li + of B-PVA8 (with 8 wt % H3BO3 added) gel electrolyte can reach 0.81, much higher than that of the conventional PVA gel electrolyte (0.32). The B-PVA8 gel electrolyte also shows the highest Li+ conductivity of 1.81 × 10–3 S cm–1 compared to PVA. The B-PVA8 gel electrolyte enables a small Li nucleation overpotential of 129.8 mV when Li is plated and reduces the concentration polarization of Li||Li batteries. The mesocarbon microbead (MCMB) half-coin cells with the B-PVA8 gel electrolyte exhibit excellent rate capability and exceptional charge/discharge cycling stability.

Transition from Vogel-Fulcher-Tammann to Arrhenius Ion-Conducting Behavior in Poly(Ethyl Acrylate)-Based Solid Polymer Electrolytes via Succinonitrile Plasticizer Addition

“…After adding 20% SN to the polyEA SPE, a sharp peak emerges in the 6 Li NMR spectrum, indicating more dissociation of lithium salts and improved movement of the Li + -coordinated moieties facilitated by the SN plasticizer. The 6 Li chemical shift of the polyEA-20% SN SPE is also downshifted to a higher field (−1.5 ppm) due to enhanced shielding effect 29 by N atoms on the SN plasticizer. With the addition of more SN (in the case of 50% SN), the sharp peak is further downshifted because more SN is coordinated with Li + .…”

Cross-Linking of Sugar-Derived Polyethers and Boronic Acids for Renewable, Self-Healing, and Single-Ion Conducting Organogel Polymer Electrolytes

“…Several groups have exploited the single-ion conducting − and anion-trapping − capabilities of boron in polymer electrolyte systems. Among these, Mecerreyes and co-workers have recently reported single-ion conducting GPEs with high ambient ionic conductivity (0.71 × 10 –3 S cm –1 at 25 °C) and transference numbers of up to 0.85 based upon lithium borate methacrylate polymers. , Meanwhile, Chen et al have developed a hydrogel electrolyte through the copolymerization of methacrylate and acrylamide monomers in the presence of borate.…”

Chemo-electro-mechanics of nanodefects in solid-state batteries: A phase-field simulation

“…[52,53] Thus, the simulation results revealing the synergistic effect of interfacial nanovoids and the electrochemical properties of GBs highlight the tradeoff between stack pressure and Li dendrite formation at nanodefects in SEs. To resolve this dilemma, recent studies have utilized gel-polymer-based interfacial ion-conductive layers, including a H3BO3 aqueous solution [54] (σ at room temperature (σRT) = 1.81 mS•cm −1 [55]), Li3OCl [56] (σRT = 0.2 mS•cm −1 [57]), and perfluoropolyether (PFPE) (σRT = 0.5 mS•cm −1 [58]). These layers exhibited notable cycling performance and prevented short circuits induced by Li dendrite formation.…”