A Heat-Resistant Poly(oxyphenylene benzimidazole)/Ethyl Cellulose Blended Polymer Membrane for Highly Safe Lithium-Ion Batteries

Abstract

A blended membrane based on poly­(oxyphenylene benzimidazole) (PBI) and ethyl cellulose (EC) exhibits heat resistance and good electrochemical performance. The prepared blended polymer gel membranes show no visible dimensional change after being held at 350 °C for 30 min, whereas the polyethylene (PE) separator almost completely melts. In addition to excellent thermal stability, the self-supporting blended membranes also exhibit a uniform thermal distribution during the heating process from 60 to 200 °C. Additionally, the ionic conductivities of the PBI/EC blended membranes with different ratios are 1.24 mS cm–1 (1:1), 2.58 mS cm–1 (1:2), and 1.68 mS cm–1 (1:3), which are much higher than those of the PE separator (0.39 mS cm–1). Compared to that of the PE separator (113 mAh g–1), the cell with a separator of PBI/EC = 1:2 retained a discharge capacity of 131 mAh g–1 after 150 cycles at 0.5C. Meanwhile, the rate performance of the cell was also better than that of the PE separator, especially at high currents (5C). All of the results indicate that this blended polymer gel membrane with good thermal stability is expected to be applied to high-performance lithium-ion batteries.

Preparation and Properties of an Alginate-Based Fiber Separator for Lithium-Ion Batteries

“…As shown in Figure a, the sharp degradation of PP membrane at about 250 °C can be ascribed to the degradation of the polyolefin backbone, , and the peak degradation of the PP separator occurred at 350 °C. In addition, when the temperature rose to 385 °C, the PP separator rapidly degraded and the weight loss of it reached 100% . In contrast, the composite membrane had three distinct stages of weight loss.…”

“…As illustrated in Figure a, the obtained discharge capacity of the battery using the alginate-based fiber separator after 50 cycles was 162 mAh/g, while the battery by the PP membrane could not be charged and discharged. The open-circuit voltage (OCV) can directly monitor the actual battery situation at elevated temperatures . The result for the battery under 120 °C heat exposure is shown in Figure b.…”

Low‐Cost and Heat‐Resistant Poly(catechol/polyamine)‐Silica Composite Membrane for High‐Performance Lithium‐Ion Batteries

“…From Figure 6A, the decomposition voltage of the cell assembled with PE@SiO 2 ‐PCPA composite membrane is 4.75 V, which is higher than that based on traditional liquid electrolyte, indicating that the addition of the PCPA coating can enhance the electrochemical oxidation stability of the batteries. The improved electrochemical stability of the separator is mainly due to the polar groups of the SiO 2 and the PCPA coatings, such as −OH and −NH, which can interact with the electrolyte to slow down decomposition [42] . Furthermore, the PCPA coating could stable the interface of polymer and inorganic filler, which makes the interaction between the polymer and liquid electrolyte stronger [43] .…”

“…The improved electrochemical stability of the separator is mainly due to the polar groups of the SiO 2 and the PCPA coatings, such as À OH and À NH, which can interact with the electrolyte to slow down decomposition. [42] Furthermore, the PCPA coating could stable the interface of polymer and inorganic filler, which makes the interaction between the polymer and liquid electrolyte stronger. [43] The results mean that the composite membrane may have extremely high application potential in highvoltage lithium-ion batteries.…”

Aramid Nanofibers Reinforced Cellulose Paper-Based Lithium-Ion Battery Separator with Improved Safety and Cycling Stability

“…The rst stage was a slight weight loss of water moisture (before 200°C). The second stage from 250 to 350°C was a major weight loss, arising from the degradation of cellulose backbone (Chen et al 2020). Additionally, one minor weight loss occurred at about 520°C for the CF/ANF-20 composite separator, corresponding to the degradation of ANFs polymer backbone (Luo et al 2019).…”