Nanostructured Polymer Particles as Additives for High Conductivity, High Modulus Solid Polymer Electrolytes

Abstract

For the next generation of safe and high energy rechargeable lithium metal batteries, we introduce nanostructured polymer particles of asymmetric miktoarm star copolymers as additives to liquid electrolytes for use as solid polymer electrolytes (SPE). The mechanical properties of the resulting SPEs are dramatically improved compared to the pure liquid electrolyte (the elastic modulus increased by up to 8 orders of magnitude), while the ionic conductivity was maintained close to that of the pure liquid electrolyte. In particular, the addition of 44 wt % miktoarm stars, composed of ion conducting poly­(ethylene oxide), PEO, arms that complement stiff insulating polystyrene arms, PS ((PS) n (PEO) n , where n = 30 the number of arms), in a low molecular weight PEO doped with lithium bis­(trifluoro­methane)­sulfonamide (LiTFSI), resulted in SPEs with a shear modulus of G′ ∼ 0.1 GPa and ion conductivity σ ∼ 10–4 S/cm. The SPEs show a strong decoupling between the mechanical behavior and the ionic conductivity as G′ remains fairly constant for temperatures up to the glass transition temperature of the PS blocks, while the conductivity monotonically increases reaching σ ∼ 10–2 S/cm. Our strategy offers tremendous potential for the design of all-polymer nanostructured materials with optimized mechanical properties and ionic conductivity over a wide temperature window for advanced lithium battery technology.

Simultaneous Improvement of Ionic Conductivity and Mechanical Strength in Block Copolymer Electrolytes with Double Conductive Nanophases

“…In order to enhance the mechanical strength of SPEs without sacrifice of ionic conductivity, multiphase nanostructured electrolytes have been proposed. [ 3,4 ] For instance, microphase‐separated block copolymer (BCP) electrolyte, containing both ion‐conducting microdomain and mechanically robust microdomain, is one of the most promising lines of investigation. [ 5–8 ] In addition, the coordination of lithium salts with the solvating blocks (e.g., poly(ethylene oxide) (PEO)) can change the overall BCP self‐assembly morphology such as spheres, hexagonally packed cylinders (Hex), bicontinuous gyroid or lamellae (Lam), resulting in the corresponding change of ionic conductivity and mechanical properties of the BCP electrolytes.…”

“…In addition to the self‐assembly morphology, the ionic conductivity is thought to be affected by the domain boundaries between the microphase separated domains and the bending/torsion of the ion‐conducting microdomain. [ 4,9,10 ]…”

Designing disordered hyperuniform two-phase materials with novel physical properties

“…Heterogeneous materials that consist of different phases (or constituent materials) abound in nature and synthetic products, such as composites, polymer blends, porous media, and powders [1][2][3][4]. In many instances, the length scale of the inhomogeneities is much smaller than the macroscopic length scale of the material, and microscopically the material can be viewed as a homogeneous material with macroscopic or effective properties [1,[5][6][7][8].…”

Self‐Healing Polymer Electrolytes Formed via Dual‐Networks: A New Strategy for Flexible Lithium Metal Batteries

“…Interestingly, the decomposition temperature of UPy‐BCDMA 1 is higher than UPy‐DMA 1 (copolymer obtained from RAFT polymerization of PEGMA, UPyMA, and PEGDA), indicating that the amount of hydrogen bonding is more than the counterpart, because the hydrogen bonding increases the thermal stability of the polymer . The effectiveness of dual‐network copolymers can mechanically reinforce the SHPE as seen in rheological characterization . Figure S4 shows that the storage modulus ( G ′) of UPy‐BCDMA is 4.0×10 5 Pa and dominates the loss modulus G “ in all of the frequency ranges.…”

“…[39] The effectiveness of dual-network copolymers can mechanically reinforce the SHPE as seen in rheologicalc haracterization. [40] Figure S4 shows that the storagem odulus (G')o fU Py-BCDMA is 4.0 10 5 Pa and dominatest he loss modulus G"i na ll of the frequencyr anges. G' increases gradually with PEGBCDMA content in polymer systemsw ith reinforcement of the dual-network in copolymers.…”