Achieve High Dielectric and Energy-Storage Density Properties by Employing Cyanoethyl Cellulose as Fillers in PVDF-Based Polymer Composites

Power Frequency Breakdown Properties of LDPE-Doped Inorganic Nanoparticles

Although polyethylene is widely used in electrical insulation, it does not possess dielectric properties. It is therefore desirable to develop insulation materials with excellent dielectric properties. In this study, low-density polyethylene (LDPE) was used as a matrix resin, while MgO, wollastonite, and montmorillonite (MMT) were employed as inorganic nano-additives. Three composites were prepared using the boiling-melt blending approach. Power frequency breakdown tests were performed on the original LDPE and on the prepared nanoparticle/LDPE composites. Upon combination with the Weibull distribution, the breakdown test results revealed that the addition of these nano-additive particles to the LDPE matrix increased the breakdown field strength of the material. The highest breakdown field strength for the nano-MgO/LDPE composite was obtained using a MgO loading of 0.5%. Notably, the obtained value was 1.8% higher than that of the pure LDPE. In addition, the highest breakdown field strength for the nano-wollastonite/LDPE composite was obtained using a wollastonite loading of 1% (7.48% higher than that of pure LDPE). Similarly, the highest breakdown field strength of the nano-MMT/LDPE composite was obtained using an MMT loading of 3%, giving a value that was 6.67% higher than that of the pure LDPE.

Bilayer Heterostructure Electrolytes Were Prepared by a UV-Curing Process for High Temperature Lithium-Ion Batteries

Solid-state electrolytes are widely anticipated to revitalize high-energy-density and high-safety lithium-ion batteries. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for their practical application. In this work, the dual-matrix concept is applied to the design of a bilayer heterogeneous structure. The electrolyte in contact with the cathode blends PVDF-HFP and oxidation-resistant PAN. In contrast, the electrolyte in contact with the anode blends PVDF-HFP and reduction-resistant PEO. A UV-curing process was used to fabricate the bilayer heterostructure electrolyte. The heterostructure electrolyte exhibits an ionic conductivity of 4.27 × 10-4 S/cm and a Li+ transference number of 0.68 at room temperature. Additionally, when assembled into LiFePO4/CPEs/Li batteries, it shows a high initial discharge capacity at room temperature (168 mAh g-1 at 0.1 C and 60 mAh g-1 at 2 C), with a capacity retention of 93.3% after 100 cycles at a current density of 0.2 C. Notably, at 60 °C, the battery maintains a discharge capacity of 90 mAh g-1 at 2 C, with a capacity retention of 97.4% after 100 cycles at 0.2 C. Therefore, solid-state batteries using this bilayer heterogeneous structure electrolyte demonstrate promising performance, including effective capacity output and cycling stability.

Research on the energy storage performance of laminated composites based on multidimensional co-design in a broad temperature range

Polymer dielectrics play an irreplaceable role in electronic power systems because of their high power density and fast charge-discharge capability, but it is limited by their low stability in the temperature range of 25-200 °C. Rather than the introduction of one-dimensional fillers in polymers, we used a kind of multidimensional synergistic design to prepare Al2O3-TiO2-Al2O3/PI composites with layered structures by introducing multi-dimensional materials in polyimide (PI). In fact, the composite achieves much higher temperature stability than the pure PI film. The optimally proportioned composite has an energy density of 3.41 J cm-3 (vs. 1.48 J cm-3 for pure PI) even at 200 °C. Additionally, it reaches an impressive energy density retention of up to 90% and maintains an energy efficiency as high as 86% at 400 MV m-1 in the temperature range of 25-200 °C. The multidimensional coordination design is proposed to obtain composite films, and provides a feasible strategy in the study of polymer-based composites with high-temperature performance.