Sheng Huang

Over the past decades, biodegradable polymer films have gained significant attention owing to their environmental friendliness and abundant raw material availability. However, the barrier properties of biodegradable polymers as packaging materials remain inferior to those of traditional petroleum-based plastic films, limiting their suitability for applications sensitive to oxygen or moisture such as food preservation, pharmaceutical packaging, and electronic device protection. In this paper, we summarize effective strategies to enhance the barrier properties of biodegradable polymer packaging films, such as surface coating, polymer blending, multilayer compounding, copolymerization and modification, nanocomposite technology, and filler reinforcement. Subsequently, we discuss the application of these strategies to biodegradable polymers, including both natural and synthetic varieties. A central focus is elucidating the relationship between the modification approaches, molecular structure, and oxygen/water barrier properties in high-barrier biodegradable polymer materials, aiming to provide valuable guidance for the development of advanced biodegradable polymer packaging materials. Finally, we present the existing challenges and future prospects for the development of high-barrier biodegradable polymer packaging materials.

Solar energy, as a clean and renewable resource, plays a pivotal role in the global energy landscape due to mitigate environmental pollution and resource depletion. Photovoltaic (PV) modules, which enable efficient photoelectric conversion, are critically dependent on encapsulant materials to ensure long-term reliability and performance. However, these materials often limit the lifespan of solar cells under harsh outdoor conditions. This review systematically examines the performance, challenges, and future trends of mainstream and emerging encapsulant materials for crystalline silicon solar cells, N-type high-efficiency crystalline silicon solar cells (e.g., HJT, TOPCon, IBC), and perovskite solar cells (PSCs). It elaborates on the classification, the advantages, disadvantages and application areas, key performance indicators (e.g., barrier properties, adhesion strength) and practical industrial challenges of materials such as ethylene-vinyl acetate copolymer (EVA), polyolefin elastomers (POE), polyvinyl butyral (PVB), and thermoplastic polyurethane (TPU). The analysis underscores the importance of developing high-performance, durable, and sustainable encapsulation solutions to support the advancement of PV technology. This work aims to provide a comprehensive reference for the research and development of next-generation photovoltaic modules with enhanced efficiency and lifespan.

The development of sustainable encapsulation materials with tunable thermomechanical properties remains a critical challenge for photovoltaic reliability. Currently, the mainstream encapsulant for polycrystalline silicon solar cells is crosslinked EVA (Ethylene-Vinyl Acetate), which complicates the end-of-life recycling and reuse of modules. There is an urgent need to develop a novel encapsulant that combines excellent barrier properties with thermoplastic recyclability. Herein, we report a novel series of thermally decomposable CO₂-based thermoplastic polyurethane (PPC-TE) films engineered through the rational design of soft and hard segments. Utilizing polycarbonate diol (PPCDL) and polyether glycol (PEG) as soft segments, we systematically tailor material properties by modulating PEG-to-PPCDL ratios (5–20 wt%) and PEG molecular weights (1000–4000 g/mol). The optimized PPC-TE films exhibit excellent transmittance (>90%), adjustable glass transition temperature (T_g: 35.1 °C~11.6 °C), and remarkable mechanical adaptability (51~92 HA). The PPC-TE films exhibit water vapor permeability (WVP) as low as 14.8 g·mm·m⁻²·day⁻¹ and oxygen permeability (OP) of 4.13 cc·mm·m⁻² day⁻¹ at 15 wt% PEG content, surpassing commercial ethylene–vinyl acetate (EVA) encapsulants. Notably, these films demonstrate fully thermal decomposition above 350 °C, facilitating eco-friendly photovoltaic device recycling. Superior adhesion to glass substrates is evidenced by peel strengths up to 37 N/cm (PPC-TE2000-20) and the shrinkage rate is as low as 3%. This work contributes to improving the long-term stability of solar cells and has the potential for large-scale production.

Proton exchange membrane fuel cells (PEMFCs) offer a promising solution for power generation, boasting higher efficiency than traditional coal combustion engines and a more environmentally friendly design. Proton exchange membranes play a crucial role in determining the overall performance of PEMFCs. Significant efforts have been dedicated to this area, resulting in the development of innovative material systems. Membranes employing phosphoric acid (PA) as the proton conductor currently dominate the field of high-temperature proton exchange membranes operating in the temperature range of 100~200 °C. This paper aims to provide a concise overview of high-temperature proton exchange membranes (HT-PEMs) to aid researchers in obtaining essential information efficiently. The proton conduction and fundamental principles, recent research efforts and limitations, as well as the challenges and promising directions for future advancements of PA-dependent HT-PEMs are summarized.

A novel low-cost poly(propylene carbonate-co-epichlorohydrin) (PPC-ECH) with mechanical properties similar to those of poly (butylene adipate-co-terephthalate) (PBAT) was developed and incorporated into a poly(propylene carbonate-co-phthalate) (PPC-P) matrix. Meanwhile, 4, 4′-diphenylmethane diisocyanate (MDI) was employed as a reactive compatibilizer and mixed with PPC-P and PPC-ECH to create a variety of PPC-P/PPC-ECH/MDI blends. The effects of PPC-ECH and MDI content on the mechanical, optical, thermal, morphological, and gas barrier properties of the blends were systematically investigated. Results demonstrated that MDI reacts with both PPC-P and PPC-ECH, forming a chemically bonded interface that significantly improves their compatibility. Notably, when 2 phr of MDI was incorporated, the elongation at break of the PPC-P/PPC-ECH/2MDI blend increased dramatically from 71% to 502%, while maintaining good tensile strength (~23 MPa) and light transmittance (~80%). To further enhance the gas barrier performance, a high-oxygen-barrier poly(vinyl alcohol) (PVA)/tannic acid (TA) complex coating was applied to the surface of the PPC-P/PPC-ECH/2MDI film. This coating synergistically leveraged the abundant hydroxyl groups in PVA and TA to form a dense hydrogen-bonded network, reducing oxygen permeability to an ultra-low value of 0.1 cm³·mm/(m²·day). This outstanding performance highlights the strong potential of PPC-P/PPC-ECH-based films for advanced packaging applications.

High-temperature proton exchange membranes (HT-PEMs) are critical components of high-temperature fuel cells, facilitating proton transport and acting as a barrier to fuel and electrons; however, their performance is hampered by persistent issues of phosphoric acid leaching and oxidative degradation. Herein, a novel HT-PEM with abundant hydrogen bond network is constructed by incorporating nanoscale polyhedral oligomeric silsequioxane functionalized with eight pendent sulfhydryl groups (POSS-SH) into poly(4,4′-diphenylether-5,5′-bibenzimidazole) (OPBI) matrix. POSS, a cage-like nanostructured hybrid molecule, features a well-defined silica core and highly designable surface organic groups, offering unique potential for enhancing membrane performance at the molecular level. Through controlled reactions between sulfhydryl groups and allyl glycidyl ether (AGE), two functional POSS crosslinkers—octa-epoxide POSS (OE-POSS) and mixed sulfhydryl-epoxy POSS (POSS-S-E)—were synthesized. These were subsequently used to fabricate crosslinked OPBI membranes (OPBI-OE-POSS and OPBI-POSS-S-E) via epoxy–amine coupling. The OPBI-POSS-S-E membranes demonstrated exceptional oxidative stability, which is attributed to the free radical scavenging ability of the retained sulfhydryl groups on the nano-sized POSS framework. After soaking in Fenton’s reagent at 80 °C for 108 h, the OPBI-POSS-S-E-20% membrane retained 79.4% of its initial weight, significantly surpassing both the OPBI-OE-POSS-20% and pristine OPBI membranes. The PA-doped OPBI-POSS-S-E-20% membrane achieved a proton conductivity of 50.8 mS cm⁻¹ at 160 °C, and the corresponding membrane electrode assembly delivered a peak power density of 724 mW cm⁻², highlighting the key role of POSS as a nano-modifier in advancing HT-PEM performance.

During the fabrication of dry-process lithium iron phosphate (LiFePO₄, LFP) electrodes, polyurethane binders with cross-linked architectures were synthesized via in-situ thermal initiation.

To address low stability at the lithium metal anode and lithium polysulfide shuttling is critical for high-energy-density lithium/sulfur (Li/S) pouch cells in practical applications. However, functional electrolytes that are compatible with Li anodes and S cathodes are required to construct more stable interfaces. Herein, we report a highly compatible electrolyte (NBME) containing bis(2-methoxyethoxy)methane (BME) as a single solvent with 1 M lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and 2% LiNO₃ additive. Compared to the traditional DOL/DME blend solvent, better electrochemical performance of 200 cycles in Li/Cu asymmetric cells and over 1200 h of cycling in Li/Li symmetric cells was realized with NBME electrolyte. Improved anode/electrolyte interfacial stability results from the anion-rich solvation sheath, thus forming an inorganic-rich SEI. In addition, the lithium polysulfide (LiPS) shuttle effect could be relieved in NBME electrolyte due to the low solubility of LiPS. Such synergistic effects enable the Li/S pouch cells to achieve 70% capacity retention after 60 cycles.

The cathode affects the capacity, working voltage, and cost of lithium-ion batteries. Although the binder is a small part of the cathode material, it is particularly important to the performance of the batteries. Therefore, the design and development of polymer binders with different structures and characteristics is an important topic. In this paper, an NCM811 cathode (PPC-NCM) was prepared by a solvent-free method using poly (propylene carbonate) (PPC) as the binder, with an active substance loading of 10 mg/cm². To explore the effect of the PPC binder on the electrochemical performance of the NCM811 cathode, the discharge capacity was 112.2 mAh/g with a 76.1% capacity retention after cycling more than 200 cycles at 1 C, which has a significantly better cycling performance than that of a PVDF-NCM/Li battery. The PPC/NCM/graphite full cells were also assembled to demonstrate the practical application potential of this work. It was shown that PPC as a binder can improve the cycling stability of NCM811/Li and NCM811/graphite full cells. The PPC binder used in the NCM811 cathode not only makes it extremely easy to prepare dry electrodes, but also makes it very simple to recover the electrode material by heating in the case of battery failure. This paper provides a new idea for the industrialization and development of a novel binder.

The polycondensation of carbon dioxide and diols under atmospheric pressure has significant appeal, thus making the study of catalysts in this process very important. Here, a series of CeO₂-X catalysts (X = 9/11/13) with surface modification by basic sites was synthesized via simple impregnation in KOH solution. The structure and morphology of the CeO₂-X catalysts remained unchanged after KOH treatment. However, the specific surface area of modified catalysts showed a slight decrease compared with the unmodified samples due to the notable enhancement of basic sites on the surface, resulting in improvement of CO₂ adsorption capacity. Furthermore, the catalytic performance of the resultant CeO₂-X catalysts was evaluated by solvent-free polymerization of 1,6-hexanediol (HDO) and CO₂ at atmospheric pressure (0.1 MPa) using a well-designed reaction apparatus. As a result, the modified catalysts exhibited better performance for CO₂ activation due to the existence of abundant basic sites on the surfaces, while CeO₂-11 possessed the most favorable catalytic activity and displayed an enhancement of approximately 50% in production compared with that of unmodified CeO₂.