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1. Polymer Precursor Derived LixPON Electrolytes: Toward Li−S Batteries

   https://doi.org/https://dx.doi.org/10.1021/acsami.0c03341  

   Temeche, E.; Zhang, X.; Laine, R. M. (April 2020, ACS applied materials interfaces)

   Efforts to develop polymer precursor electrolytes that offer properties anticipated to be similar or superior to (lithium phosphorus oxynitride, LiPON) glasses are reported. Such precursors offer the potential to be used to process LiPON-like thin glass/ceramic coatings for use in all solid state batteries, ASBs. Here, LiPON glasses provide a design basis for the synthesis of sets of oligomers/polymers by lithiation of OP(NH2)3−x(NH)x [from OP(NH)3],OP-(NH2)3‑x(NHSiMe3)x and [PN]3(NHSiMe3)6−x(NH)x. The resulting systems have degrees of polymerization of 5−20. Treatment with selected amounts of LiNH2 provides varying degrees of lithiation and Li+ conducting properties commensurate with Li+ content. Polymer electrolytes impregnated in/on Celgard exhibit Li+ conductivities up to ∼1 × 10−5S cm−1 at room temperature and are thermally stable to ∼150 °C. A Li−S battery assembled using a Li6SiPON composition polymer electrolyte exhibits an initial reversible capacity of 1500 mAhgsulfur −1 and excellent cycle performance at 0.25 and 0.5 C rate over 120 cycles at room temperature. 

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2. Electrochemical Performance of LixSiON Polymer Electrolytes Derived from an Agriculture Waste Product, Rice Hull Ash

   https://doi.org/10.1021/acsapm.1c00192  

   Temeche, E.; Zhang, X.; Laine, R. M. (March 2021, ACS applied polymer materials)

   The electrochemical performance of LixSiON (x = 2, 4, and 6) polymer electrolytes derived from the agricultural waste, rice hull ash (RHA, 80−90 wt % SiO2), is reported. Silica can be extracted from RHA by base-catalyzed reaction with hexylene glycol forming the spirosiloxane [(C6H12O2)2Si, SP] that distills from the reaction solution. LixSiON polymer electrolytes form on reacting SP with xLiNH2, offering a low-cost, low- temperature, and green synthesis route. The effect of N and Li+ concentrations in the polymer electrolytes are correlated with ionic and electrical conductivity. X-ray photoelectron spectroscopy studies confirm that N and Li contents increase with increasing LiNH2 content. The amorphous nature and high Li+ contents of the Li6SiON electrolyte provide an optimal ionic conductivity (6.5 × 10−6) at ambient temperature when coated on Celgard. Furthermore, the LixSiON polymer electrolytes offer high Li+ transference numbers (∼0.75−1), enabling assembly of Li symmetric cells with high critical current densities (3.75 mA cm−2). Finally, Li-SPAN (sulfurized, carbonized polyacrylonitrile) half-cells with Li6SiON polymer electrolytes deliver discharge capacities of ∼765 and 725 mAh/g at 0.25 and 0.5 C rates over 50 cycles. 

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3. A flexible thin film lithium battery with a chemical vapor deposited organic complex cathode

   https://doi.org/10.1039/D1TA10867K  

   Li, Zhuo; Hu, Fei; Huo, Ni; Tenhaeff, Wyatt E. (March 2022, Journal of Materials Chemistry A)

   Organic cathode materials have attracted significant research attention recently, yet their low electronic conductivity limits their application as solid-state cathodes in lithium batteries. This work describes the development of a novel organic cathode chemistry with significant intrinsic electronic conductivity for solid-state thin film batteries. A polymeric charge transfer complex (CTC) cathode, poly(4-vinylpyridine)-iodine monochloride (P4VP·ICl), was prepared by initiated chemical vapor deposition (iCVD). Critical chemical, physical, and electrochemical properties of the CTC complex were characterized. The complex was found to have an electronic conductivity of 4 × 10-7 S cm-1 and total conductivity of 2 × 10−6 S cm−1 at room temperature, which allows the construction of a 2.7 μm thick dense cathode. By fabricating a P4VP·ICl|LIPON|Li thin film battery, the discharge capacity of P4VP·ICl was demonstrated to be >320 mA h cm−3 on both rigid and flexible substrates. The flexible P4VP·ICl|LIPON|Li battery was prepared by simply replacing the rigid substrate with a flexible polyimide substrate and the as-prepared battery can be bent 180° while maintaining electrochemical performance. 

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4. Organic–inorganic hybrid electrolytes from ionic liquid-functionalized octasilsesquioxane for lithium metal batteries

   https://doi.org/10.1039/C7TA04599A  

   Yang, Guang; Chanthad, Chalathorn; Oh, Hyukkeun; Ayhan, Ismail Alperen; Wang, Qing (January 2017, Journal of Materials Chemistry A)

   The use of highly conductive solid-state electrolytes to replace conventional liquid organic electrolytes enables radical improvements in the reliability, safety and performance of lithium batteries. Here, we report the synthesis and characterization of a new class of nonflammable solid electrolytes based on the grafting of ionic liquids onto octa-silsesquioxane. The electrolyte exhibits outstanding room-temperature ionic conductivity (∼4.8 × 10 −4 S cm −1 ), excellent electrochemical stability (up to 5 V relative to Li + /Li) and high thermal stability. All-solid-state Li metal batteries using the prepared electrolyte membrane are successfully cycled with high coulombic efficiencies at ambient temperature. The good cycling stability of the electrolyte against lithium has been demonstrated. This work provides a new platform for the development of solid polymer electrolytes for application in room-temperature lithium batteries. 

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5. Solid Electrolytes for Li−S Batteries: Solid Solutions of Poly(ethylene oxide) with LixPON- and LixSiPON-Based Polymers

   https://doi.org/10.1021/acsami.0c06196  

   Temeche, E.; Zhang, X.; Laine, R. M. (June 2020, ACS applied materials interfaces)

   We report here efforts to synthesize free-standing, dry polymer electrolytes that exhibit superior ionic conductivities at ambient for Li−S batteries. Co-dissolution of poly(ethylene oxide) (PEO) (Mn 900k) with LixPON and LixSiPON polymer systems at a ratio of approximately 3:2 followed by casting provides transparent, solid-solution films 25−50 μm thick, lowering PEO crystallinity, and providing measured impedance values of 0.1−2.8 × 10−3 S/cm at ambient. These values are much higher than simple PEO/Li+ salt systems. These solid-solution polymer electrolytes (PEs) are (1) thermally stable to 100 °C; (2) offer activation energies of 0.2−0.5 eV; (3) suppress dendrite formation; and (4) enable the use of lithium anodes at current densities as high as 3.5 mAh/cm2. Galvanostatic cycling of SPAN/PEs/Li cell (SPAN = sulfurized, carbonized polyacrylonitrile) shows discharge capacities of 1000 mAh/gsulfur at 0.25C and 800 mAh/gsulfur at 1C with high coulumbic efficiency over 100 cycles. 

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