Designing Boron‐Based Single‐Ion Gel Polymer Electrolytes for Lithium Batteries by Photopolymerization

Abstract

Single-ion lithium conducting polymer electrolytes based on delocalized borate groups are designed and synthesized by rapid UV-photopolymerization. For this purpose, three different functional lithium boron sp 3 anionic monomers, containing fluorinated, ethoxy, or a blend of both functionalities are synthesized. These monomers are photopolymerized in the presence of a poly(ethylene glycol) dimethacrylate crosslinker and tetraglyme as plasticizer. By this method, gel polymer electrolytes endowed with lithium single-ion conduction are prepared (SIGPEs). The impact generated by the different functionalities of the borate groups and the addition of plasticizer on the electrochemical and ion conducting properties of the synthesized polymer electrolytes are analyzed in detail. These polymer electrolytes show high ionic conductivity (1.71 × 10 −4 S cm −1 at 25 °C) and high lithium transference number values (up to 0.85). Finally, they are investigated as solid electrolytes in lithium metal symmetrical cells showing good performance (<0.85 V at ±0.2 mA cm −2 for 175 h).

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. The resulting GPE showed excellent ambient ionic conductivity of 4.5 × 10 –3 S cm –1 while being able to self-heal during to the dynamic nature of its borate-diol cross-links .…”

An Industrial Perspective and Intellectual Property Landscape on Solid-State Battery Technology with a Focus on Solid-State Electrolyte Chemistries

“…Recently, the same group reported the development of SICPEs exhibiting high ambient ionic conductivity (0.71 × 10 −3 S cm −1 at 25 • C) and transference numbers of up to 0.85. These advancements were achieved through boronbased polymer formulations [33,34]. Research efforts are also delving into the exploration of complex chain structures, such as tri-and multiblock-copolymers that showcase a range of diverse properties [35,36].…”

Solid State Li Metal/LMO Batteries based on Ternary Triblock Copolymers and Ionic Binders

“…A number of solid electrolyte options have been considered for ASSBs, including ceramic conductors (such as LLZO, − LATP, − sulfides, , oxyhalides, , etc. ), deep eutectic solvent (DES)-based self-healing polymer electrolytes, − solid polymer electrolytes (SPEs), and composites (e.g., polymers combined with ceramics). − In the class of SPEs, there are also several subclasses, for example SPEs consisting of a binary mixture of a polymer host and a lithium salt; − polymers containing a low molecular weight plasticizer in addition to the lithium salt to enhance ion mobility; − ionogels, where high content ionic liquid-based electrolytes are incorporated into a polymer network structure; − and ternary systems, where the major components are the polymer and lithium salt, and ionic liquid (IL) is also included to further enhance conductivity …”