Styrene-based poly(ionic liquid) (PIL) diblock copolymers and their analogous PIL homopolymers were synthesized in this study with various covalently attached cations (methylimidazolium (MIm(+)) and methylpyrrolidinium (MPyr(+))) and counteranions (bis(trifluoromethanesulfonyl)imide (TFSI-) and bis(fluorosulfonyl)imide (FSI-)). Solid polymer electrolytes (SPEs) were prepared by mixing the polymer with the corresponding salts (Li+TFSI- and Li+FSI-) under various salt concentrations r = [Li+/[PIL] (mol/mol) = 0.1-0.8. The impacts of lithium salt concentration and cation/anion chemistry were explored in regards to electrochemical, morphological, transport, and physical properties. The results show that the SPE with the MIm(+)/FSI- ion pair has the lowest PIL T-g (-7 degrees C), ca. 1-3 orders of magnitude higher conductivity compared to other SPEs as well as high electrochemical stability (lithium-metal stripping-plating). SPEs with the FSI- anion exhibit an ion-hopping-dominated transport mechanism and similar ion conductivities compared to their analogous PIL homopolymer SPEs at the same salt concentrations. The negative transference number of the SPE with the MIm(+)/FSI- ion pair at a high salt concentration indicates the formation of larger anion-rich clusters and results in lower conductivity. This work reveals the impact of cation/anion chemistries on salt-doped PIL block polymers, which may enable new highly stable SPEs for lithium batteries.

In this study, the physical, transport, mechanical, morphological, and electrochemical properties of a ternary blend solid polymer electrolyte (SPE) (poly(ionic liquid) (PIL) multiblock polymer, lithium salt, and ionic liquid (IL)) were systematically investigated as a function of IL concentration. With increasing IL concentration, the conductive volume increases along with the polymer chain segmental mobility. This facilitates high ionic conductivity, while the mechanical modulus exhibits a percolation threshold. Surprisingly, at higher IL concentrations, there is a reduction in the lithium cation mobility as evidenced by pulsed-field gradient nuclear magnetic resonance, which coincides with an increased overpotential evidenced by lithium metal stripping and plating. Stable lithium ion battery cycling durability (over 100 cycles at room temperature) is demonstrated with the ternary blend SPE as the electrolyte and separator. This work provides valuable insights into the design of new SPEs with both high ionic conductivity and improved battery stability.

Alkaline fuel cells (AFCs) have attracted attention as low-cost alternatives to proton exchange membrane fuel cells (PEMFCs) because of their ability to produce high power densities without the use of non-precious metal catalysts. However, long-lasting AFCs require highly hydroxide conductive solid-state anion exchange membranes (AEMs) (or separators) and ionomers (for use in the catalyst layer) that are highly chemically stable at high pH. Recent results have shown that polymers with covalently attached saturated N-heterocyclic cations possess high alkaline chemical stability (ex situ), however their performance and durability as AEMs and ionomers in AFCs (in situ or in operando) have yet to be explored. In this study, the AFC performance of a multiblock polymer containing saturated N-heterocyclic cations (methylpyrrolidinium) as both the AEM and ionomer was explored. Both high power density and durability (i.e., constant power density or voltage over time) were demonstrated. AFC performance will be presented as a function of membrane electrode assembly processing conditions (ionomer content, casting solvents, cell assembly pressure) and AFC operating conditions (cell temperature, humidity). These results demonstrate the possibility to produce high power density, long-lasting, low-cost AFCs.

Lithium ion batteries are currently the leading commercial technology for portable electronic devices and electric vehicles. However, new solid polymer electrolytes (SPEs) that comprehensively possess the preferred properties of high ion conductivity, high electrochemical stability, robust mechanical properties, flexibility, and good film forming properties, are required to improve the safety and lifetime of lithium ion batteries. Although diblock copolymers have been explored as SPEs and can potentially provide the orthogonal properties of high ion conduction and high mechanical strength simultaneously in a solid-state material, there are limitations to diblock copolymer-salt mixture systems, such as a limited set of morphologies, and a lack of means to achieve simultaneous combination of more than two properties ( e.g. , conductivity, strength, flexibility). Compared to diblock copolymers, multiblock polymers involve more than two polymer chemistries and therefore enable the possibility to conjoin many of the desired properties, such as high ion conductivity, mechanical strength, flexibility, good film forming properties, processability, and high electrochemical stability all into a single materials platform. In this study, a lithium ion conducting polyionic liquid pentablock terpolymer (PILPTP) was investigated as a solid polymer electrolyte (SPE) for lithium ion batteries.The morphology, chemical, thermal, mechanical, and electrochemical properties were examined as function of ionic liquid composition, cation chemistry, and film processing conditions. Coin cell Li 4 Ti 5 O 12 /SPE/LiCoO 2 batteries were fabricated with the lithium ion conducting PILPTP as the SPE and room temperature battery performance was demonstrated at high capacity and high cycle life. Overall, this work suggests, for the first time, that lithium conducting polyionic liquid multiblock polymers can be promising electrolyte candidates for developing safe and high performing room temperature solid-state lithium ion batteries.

In this study, a lithium ion conducting polymerized ionic liquid pentablock terpolymer (PILPTP) was investigated as a solid polymer electrolyte (SPE) for lithium ion batteries. The ABCBA pentablock terpolymer, poly (tb-b-EP-b-MS-b-EP-b-tbS) (tbS = tert-butyl-styrene; EP = ethylene-r-propylene; MS = 4-methylstyrene), was brominated and quaternized to covalently attach two different cations (methylimidazolium and methylpyrro-lidinium) to the C block and subsequently ion exchanged to form two different TFSI-exchanged PILPTPs (MPyr-TFSI and MIm-TFSI; TFSI = bis(trifluoromethane)sulfonimide). Free standing, mechanically stable, transparent SPE films were produced with MPyr-TFSI and MIm-TFSI containing 1 M Li-TFSI/ionic liquid (IL) (IL = EMIm-TFSI or PYR14 -TFSI; EMIm = 1-ethyl-3-methylimidazolium, PYR14 = 1-butyl-1-methylpyrrolidinium), referred to as MPyr-TFSI + Li-TFSI/PYR14 -TFSI and MIm-TFSI + Li-TFSI/EMIm-TFSI. Both SPEs show promising ionic conductivities, electrochemical stabilities, and stripping and plating stabilities. Specifically, the MIm-TFSI + LiTFSI/EMIm-TFSI SPE possessed an ionic conductivity of 0.1 mS cm(-1) at 28 degrees C; the MPyr-TFSI + Li-TFSI/PYR14- TFSI SPE possessed an electrochemical stability window of 4.2 V versus Li/Li+ at room temperature; the MPyr-TFSI + Li-TFSI/PYR14-TFSI SPE exhibited stable stripping and plating overvoltage profiles over 500 cycles at 70 degrees C. These results demonstrate the feasibility of a PIL multiblock polymer as an SPE for lithium ion batteries.

Hybrid-capacitors have the potential to synergistically combine the benefits of both electrochemical double layer capacitors (EDLCs) (long cycle life) and Faradaic-capacitors (high capacitance). However, new processes that intimately combine the two primary materials from each capacitor (carbon and conductive polymer, respectively) within the electrodes in an ordered fashion on the nanoscale are needed to realize this potential. In this study, we report on a novel method (simultaneous electrospinning/electrospraying (E/E)) for fabricating hybrid-capacitors with high surface area electrodes consisting of polyaniline (PANI) and carbon nanoparticles (referred to as E/E electrodes). E/E produces a unique nanofiber/particle network of PANI and carbon. The hybrid-capacitor with E/E electrodes exhibits an excellent specific capacitance of 235Fg−1 (vs. 138 Fg−1 for capacitor with state-of-the art hybrid electrodes) at a current density of 1Ag−1. Moreover, the hybrid-capacitor with E/E electrodes retains approximately 84% capacitance after 1000 charge-discharge cycles (vs. 67% for capacitor with state-of-the art hybrid electrodes). These results indicate the feasibility of producing E/E electrodes and their promise as future materials in hybrid-capacitors.