No abstract

The preparation of separators using heat-resistant polymers is an effective approach to improve the safety of lithium-ion batteries (LIBs). However, separators using a single heat-resistant polymer compared with the composite modified polymer have low conductivities, which leads to low battery performances. In this study, for the first time, a heat-resistant separator was successfully prepared using an ion-modified metal–organic framework (MOF) and poly­(aryl ether benzimidazole)­(OPBI). Diversified ion channels were constructed by ion modification combined with phase inversion and physical mixing. The lithium-ion transmission efficiency and safety of the LIBs were effectively improved. The hybrid separator exhibited a satisfactory thermal stability (absence of shrinkage at 200 °C for 1 h), higher ionic conductivity (1.46 mS cm–1), and better electrolyte uptake rate. Moreover, the hybrid separator is conducive to inhibiting the growth of Li dendrites. A cell assembled with the hybrid separator delivered a reversible capacity of 157 mA h g–1 at 0.5 C. The capacity retention of the cell was up to 94% after 200 cycles. Thus, the hybrid membrane is a valuable candidate to enhance the safety and electrochemical properties of LIBs.

Constructing high-density hydrogen bonding networks is crucial to improve the proton conductivity of proton exchange membranes (PEMs) and the single-cell output power of high-temperature fuel cells (HTFCs). In this work, a series of benzimidazole polymers containing a pyridine group in the backbone are successfully synthesized via copolymerization. The high-density hydrogen network is constructed via blending the polyether polybenzimidazole (OPBI) with the bipyridine polybenzimidazole copolymer, and the 1,3,5-triglycidyl isocyanurate that contains nitrogen atoms and hydroxyl groups is used as a cross-linking agent. As a result, the proton conductivity and the output power density of the single cell are significantly enhanced by the high-density hydrogen bonding network. The single-cell performance of 693 mW cm–2 is achieved in the cross-linked OPBI/copolymer blend membranes containing pyridine group under a saturated phosphoric acid (PA) adsorption (284%). Even under the low PA uptake (178%), the proton conductivity (0.050 S cm–1) is 2.1 times that of the OPBI membrane (0.024 S cm–1), and the output power density of the single-cell performance (501 mW cm–2) is 1.4 times that of the OPBI membrane (358 mW cm–2). The results demonstrate that introducing nitrogen sites into polybenzimidazole cross-linked membranes is an effective strategy for preparing high-performance fuel cell PEMs.

No abstract

No abstract