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1. The Polymer Structure–Ion Conductivity–Mechanical Property Relationship in Comb–Chain Polymer Network Electrolytes for Sodium Metal Batteries

   https://doi.org/10.1021/acsapm.5c01262  

   Pathreeker, Shreyas S; Shah, Nisha H; Fullerton, William R; Detsi, Eric; Li, Christopher Y; Composto, Russell J (August 2025, ACS Applied Polymer Materials)

   Toughness reflects extensibility, which is critical for. accommodating electrode volume changes in batteries, primarily due to thermal expansion. However, polymer toughness has received less attention for battery dendrite suppression than polymer modulus. Inspired by rubber chemistry, here, we investigate the polymer network structure, ion conductivity, and mechanical properties of cross-linked poly(glycidyl methacrylate) (PGMA)−poly(ethylene glycol) (PEG) networks containing sodium bis (fluorosulfonyl imide) (NaFSI) salt. We explore two PGMA:PEG molar ratios (1:1 and 5:1), and three salt concentrations (Na+ to EO: (r) = 0.01, 0.0625, and 0.25), and observe that lower PGMA content results in higher hydrophilicity and lower cross-link density. These properties translate to a total ion conductivity of 0.5 × 10−4 S/cm at 25 °C and nearly 0.5 × 10−3 S/cm at 65 °C for the optimum composition (1:1) and salt concentration (r= 0.0625). The polymer electrolytes exhibit good mechanical properties (elongation at strain between 125 and 140%, Young’s modulus between 0.3 and 0.7 MPa, and toughness between 0.25 and 0.70 MJ/m3). By virtue of their high ion conductivity and toughness, these comb−chain network SPEs have the potential to exhibit excellent cycling performance in emerging sodium metal batteries. 

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2. Effect of Confinement on the Structure–Conductivity Relationship in PEO/LiTFSI Electrolytes in 3D Microporous Scaffolds

   https://doi.org/10.1021/acsmacrolett.4c00555  

   Pathreeker, Shreyas; Koh, Hyeongjun; Kong, Weiwei; Robinson, Richard; Weissman, Gillian; Stach, Eric A; Detsi, Eric; Composto, Russell J (November 2024, ACS Macro Letters)

   Because 3D batteries comprise solid polymer electrolytes (SPE) confined to high surface area porous scaffolds, the interplay between polymer confinement and interfacial interactions on total ionic conductivity must be understood. This paper investigates contributions to the structure-conductivity relationship in poly(ethylene oxide) (PEO)–lithium bis(trifluorosulfonylimide) (LiTFSI) complexes confined to microporous nickel scaffolds. For bulk and confined conditions, PEO crystallinity decreases as the salt concentration (Li+:EO (r) = 0.0.125, 0.0167, 0.025, 0.05) increases. For pure PEO and all r values except 0.05, PEO crystallinity under confinement is lower than in the bulk, whereas glass transition temperature remains statistically invariant. At 298 K (semicrystalline), total ionic conductivity under confinement is higher than in the bulk at r = 0.0167, but remains invariant at r = 0.05; however, at 350 K (amorphous), total ionic conductivity is higher than in the bulk for both salt concentrations. Time–of–flight secondary ion mass spectrometry indicates selective migration of ions towards the polymer–scaffold interface. In summary, for the 3D structure studied, polymer crystallinity, interfacial segregation, and tortuosity play an important role in determining total ionic conductivity and, ultimately, the emergence of 3D SPEs as energy storage materials. 

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3. Highly Conductive Polyoxanorbornene‐Based Polymer Electrolyte for Lithium‐Metal Batteries

   https://doi.org/10.1002/advs.202302932  

   An, So Young; Wu, Xinsheng; Zhao, Yuqi; Liu, Tong; Yin, Rongguan; Ahn, Jung Hyun; Walker, Lynn M.; Whitacre, Jay F.; Matyjaszewski, Krzysztof (September 2023, Advanced Science)

   Abstract This present study illustrates the synthesis and preparation of polyoxanorbornene‐based bottlebrush polymers with poly(ethylene oxide) (PEO) side chains by ring‐opening metathesis polymerization for solid polymer electrolytes (SPE). In addition to the conductive PEO side chains, the polyoxanorbornene backbones may act as another ion conductor to further promote Li‐ion movement within the SPE matrix. These results suggest that these bottlebrush polymer electrolytes provide impressively high ionic conductivity of 7.12 × 10⁻⁴S cm⁻¹at room temperature and excellent electrochemical performance, including high‐rate capabilities and cycling stability when paired with a Li metal anode and a LiFePO₄cathode. The new design paradigm, which has dual ionic conductive pathways, provides an unexplored avenue for inventing new SPEs and emphasizes the importance of molecular engineering to develop highly stable and conductive polymer electrolytes for lithium‐metal batteries (LMB). 

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4. Morphology control in semicrystalline solid polymer electrolytes for lithium batteries

   https://doi.org/10.1039/C9ME00028C  

   Li, Xiaowei; Cheng, Shan; Zheng, Yongwei; Li, Christopher Y. (August 2019, Molecular Systems Design & Engineering)

   Solid polymer electrolytes (SPEs) are one of the most promising solutions to the safety issues of lithium batteries. Understanding the morphology and dynamic effects on the ion transport properties of SPEs would be essential for future SPE design. In this article, using poly(ethylene oxide) (PEO) as an example, we focus on morphology control in semicrystalline SPEs. We show that the effect of semicrystallinity can be quantitatively separated into volume, structure and dynamic effects. We further demonstrate that morphological control plays an important role in ion transport control in semicrystalline SPE systems. 

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5. Quantification of the Impact of Crosslinking on Ionic Conductivity and Electro-Chemo-Mechanical Properties of Poly(ethylene oxide)-Based Solid Polymer Electrolytes

   https://doi.org/10.1149/1945-7111/add8c0  

   Liu, Bing; Xie, Yuzheng; Lin, Ruoqian (May 2025, Journal of The Electrochemical Society)

   Non-crosslinked poly(ethylene oxide) (PEO) is widely studied for its lithium-ion conductivity and applications as solid polymer electrolytes (SPEs) for lithium-metal-anode batteries (LMBs), but its mechanical softness remains a barrier to roll-to-roll manufacturing. Crosslinking in polymer synthesis can reinforce PEO-based SPEs by linking polymer chains into a three-dimensional network, making them compatible with roll-to-roll processing. Although crosslinking may reduce lithium-ion conductivity by limiting segmental motion, the resulting mechanical enhancement can suppress dendrite growth, improving the reversibility of lithium-metal anodes. Understanding the relationship between the degree of crosslinking, mechanical properties, glass transition temperature, ionic conductivity, and electrochemical reversibility in LMBs is therefore of fundamental importance. Here, we systematically quantify the impact of crosslinking on the ionic, electrochemical, and mechanical properties of PEO. The results indicate that higher crosslinking enhances SPEs’ mechanical strength but reduces ionic conductivity, consistent with the rise in glass transition temperature, supporting the theory that segmental motion governs lithium-ion conduction in PEO. Meanwhile, although crosslinking reduces the limiting current density, whereas the critical current density benefits from mechanical reinforcement of SPEs brought by crosslinking, thereby enhancing the reversibility of lithium-metal anodes. This work provides the opportunity to improve the electro-chemo-mechanical properties of PEO-based SPEs for LMBs. 

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