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1. Polymer Blends of Poly(ethylene oxide) and Phosphonium Ionenes As Solid Polymer Electrolyte Membranes for Lithium Ion Batteries

   https://doi.org/10.1149/MA2020-01522891mtgabs  

   Callaway, Jumia; Abdulahad, Asem (May 2020, ECS Meeting Abstracts)

   Solid polymer electrolytes offer potential improvements to lithium ion batteries that include extending their operating temperature range and improving the safe use of the batteries by inhibiting lithium dendrite formation. Because solid polymer electrolytes replace traditional liquid electrolytes as the lithium ion transport medium and also act as the electrode separator, these materials must offer good ionic conductivity along with providing good interfacial contact with the electrode material. This work presents the synthesis and characterization of polymer blends comprised poly(ethylene oxide) and phosphonium ionenes. Ionenes are a class of polycation that includes positive charges within the polymer backbone. Because the positive charge is a part of the polymer chain, the spacing and distribution of these charges have a significant impact on the properties of ionenes. This research focuses on determining the role of charge spacing and distribution of charges along the backbone of phosphonium ionenes on their ability to transport lithium ions. To accomplish this, phosphonium ionenes are blended with low molecular weight poly(ethylene oxide) (e.g. less than 3,000 g/mol) at mass ratios of 20:1, 10:1, and 5:1. The resulting blended solid polymer electrolyte membranes are evaluated for their thermal, mechanical and electrochemical properties along with their charge/discharge performance in coin cell batteries. The dependence of phosphonium ionene structure as well as the composition of SPE blends will be presented. 

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2. Maleimide-functionalized metal–organic framework for polysulfide tethering in lithium–sulfur batteries

   https://doi.org/10.1039/D1MA00084E  

   Burns, David A.; Benavidez, Angelica; Buckner, Jessica L.; Thoi, V. Sara (May 2021, Materials Advances)

   Lithium–sulfur (Li–S) batteries have great potential as next generation energy storage devices. However, the redox chemistry mechanism involves the generation of solubilized lithium polysulfides, which can lead to leaching of the active material and, consequently, passivated electrodes and diminished capacities. Chemical tethering of lithium polysulfides to materials in the sulfur cathode is a promising approach for resolving this issue in Li–S batteries. Borrowing from the field of synthetic chemistry, we utilize maleimide functional groups in a Zr-based metal–organic framework to chemically interact with polysulfides through the Michael Addition reaction. A combination of molecular and solid-state spectroscopies confirms covalent attachment of Li 2 S x to the maleimide functionality. When integrated into Li–S cathodes, the maleimide-functionalized framework exhibits notable performance enhancements over that of the unfunctionalized material, revealing the promise of polysulfide anchors for Li–S battery cycling. 

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3. Nickel enrichment of next-generation NMC nanomaterials alters material stability, causing unexpected dissolution behavior and observed toxicity to S. oneidensis MR-1 and D. magna

   https://doi.org/10.1039/C9EN01074B  

   Buchman, Joseph T.; Bennett, Evan A.; Wang, Chenyu; Abbaspour Tamijani, Ali; Bennett, Joseph W.; Hudson, Blake G.; Green, Curtis M.; Clement, Peter L.; Zhi, Bo; Henke, Austin H.; et al (February 2020, Environmental Science: Nano)

   Lithium intercalation compounds, such as the complex metal oxide, lithium nickel manganese cobalt oxide (LiNi x Mn y Co 1−x−y O 2 , herein referred to as NMC), have demonstrated their utility as energy storage materials. In response to recent concerns about the global supply of cobalt, industrially synthesized NMCs are shifting toward using NMC compositions with enriched nickel content. However, nickel is one of the more toxic components of NMC materials, meriting investigation of the toxicity of these materials on environmentally relevant organisms. Herein, the toxicity of both nanoscale and microscale Ni-enriched NMCs to the bacterium, Shewanella oneidensis MR-1, and the zooplankton, Daphnia magna , was assessed. Unexpectedly, for the bacteria, all NMC materials exhibited similar toxicity when used at equal surface area-based doses, despite the different nickel content in each. Material dissolution to toxic species, namely nickel and cobalt ions, was therefore modelled using a combined density functional theory and thermodynamics approach, which showed an increase in material stability due to the Ni-enriched material containing nickel with an oxidation state >2. The increased stability of this material means that similar dissolution is expected between Ni-enriched NMC and equistoichiometric NMC, which is what was found in experiments. For S. oneidensis , the toxicity of the released ions recapitulated toxicity of NMC nanoparticles. For D. magna , nickel enrichment increased the observed toxicity of NMC, but this toxicity was not due to ion release. Association of the NMC was observed with both S. oneidensis and D. magna. This work demonstrates that for organisms where the major mode of toxicity is based on ion release, including more nickel in NMC does not impact toxicity due to increased particle stability; however, for organisms where the core composition dictates the toxicity, including more nickel in the redesign strategy may lead to greater toxicity due to nanoparticle-specific impacts on the organism. 

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4. Lithium Trithiocarbonate as a Dual‐Function Electrode Material for High‐Performance Lithium–Sulfur Batteries

   https://doi.org/10.1002/aenm.202200680  

   Sul, Hyunki; Bhargav, Amruth; Manthiram, Arumugam (April 2022, Advanced Energy Materials)

   Abstract The development of practical lithium–sulfur (Li–S) batteries with prolonged cycle life and high Coulombic efficiency is limited by both parasitic reactions from dissolved polysulfides and mossy lithium deposition. To address these challenges, here lithium trithiocarbonate (Li₂CS₃)‐coated lithium sulfide (Li₂S) is employed as a dual‐function cathode material to improve the cycling performance of Li–S batteries. Interestingly, at the cathode, Li₂CS₃forms an oligomer‐structured layer on the surface to suppress polysulfide shuttle. The presence of Li₂CS₃alters the conventional sulfur reaction pathway, which is supported by material characterization and density functional theory calculation. At the anode, a stable in situ solid electrolyte interphase layer with a lower Li‐ion diffusion barrier is formed on the Li‐metal surface to engender enhanced lithium plating/stripping performance upon cycling. Consequently, the obtained anode‐free full cells with Li₂CS₃exhibit a superior capacity retention of 51% over 125 cycles, whereas conventional Li₂S cells retain only 26%. This study demonstrates that Li₂CS₃inclusion is an efficient strategy for designing high‐energy‐density Li–S batteries with extended cycle life. 

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5. A Comparative Study on Electrochemical Performance of Single versus Dual Networks in Lithium Metal/Polysulfide-Polyoxide Co-Network/Lithium Titanium Oxide Cathode

   https://doi.org/10.3390/batteries10050163  

   Lee, Hyunsang; Choi, Jae-Won; Kyu, Thein (May 2024, Batteries)

   The present article introduces a strategy for controlling oxidation and reduction reactions within polymer electrolyte membrane (PEM) networks as a means of enhancing storage capacity through the complexation of dissociated lithium cations with multifunctional groups of the polymer network. Specifically, co-polymer networks based on polysulfide (PS) and polyoxide (PO) precursors, photo-cured in the presence of succinonitrile (SCN) and lithium bis(trifluoro methane sulfonyl imide) (LiTFSI) salt, exhibited ionic conductivity on the order of mid 10−4 S/cm at ambient temperature in the 30/35/35 (weight %) composition. Lithium titanate (LTO, Li4Ti5O12) electrode was chosen as an anode (i.e., a potential source of Li ions) against lithium iron phosphate (LFP, LiFePO4) cathode in conjunction with polysulfide-co-polyoxide dual polyelectrolyte networks to control viscosity for 3D printability on conformal surfaces of drone and aeronautic vehicles. It was found that the PS-co-PO dual network-based polymer electrolyte containing SCN plasticizer and LiTFSI salt exhibited extra storage capacity (i.e., specific capacity of 44 mAh/g) with the overall specific capacity of 170 mAh/g (i.e., for the combined LTO electrode and PEM) initially that stabilized at 153 mAh/g after 50th cycles with a reasonable capacity retention of over 90% and Coulombic efficiency of over 99%. Of particular interest is the observation of the improved electrochemical performance of the polysulfide-co-polyoxide electrolyte dual-network relative to that of the polyoxide electrolyte single-network. 

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