目前锂离子电池中使用的隔膜主要是聚烯烃类,包括单层的聚丙烯(PP)、聚乙烯(PE)以及复合的 PP/PE/PP 隔膜等[4-6]。但聚烯烃隔膜存在表面疏水性、热稳定性差和易燃的弊端,严重影响锂离子电池的安全和性能[3, 7]。另外从发展趋势来看,传统聚烯烃隔膜,来源于石油基原料,不可再生、不可降解、不符合环境友好与持续发展的大趋势[8]。因此,越来越多新的材料被尝试用于锂离子电池隔膜[9]。生物质原料,特别是纤维素原料,储量丰富、可再生、可降解、容易获得和价格合适,是代替石油基原料的最佳选择[10]。纤维素是世界上存量最大的天然生物质原料,全世界每年的产量在 1010-1011吨,除主要来源于木材外,也来源于其它植物如棉、麻、海洋藻类和菌类[10]。纤维素不仅提取加工过程简单成熟,更重要的,纤维素材料有良好的物化性能、生物相容性、无毒性、轻质性、可循环性、环境友好等,特别是优良的表面亲液性和热稳定性,使其受到众多关注,是代替传统聚烯烃隔膜的最佳候选[11]。例如,Sheng等采用简单的乙醇浸泡工艺制备超轻和超薄纤维素纳米纤维膜。所获得的隔膜的重量和厚度仅为传统聚烯烃膜的一半[1];Wu 等人提出了一种Cu2+交联壳聚糖(壳聚糖-铜)材料作为稳定和高性能的离子交换膜[12];Zhang等使用北方漂白软木牛皮纸(NBSK)纤维,聚磺酰胺(PSA)纤维和纳米纤维素(NFC)通过湿法制备用于锂离子电池的耐热复合膜[13]。
然而,目前所报道的大多数纤维素隔膜耐酸/碱性差、强度低或易燃[2];大多数研究仅使用棉浆纤维作为原料,原料单一且纤维强度低[14];纳米纤维素仅作为增强或辅助材料改善聚烯烃类隔膜[15]。因此,提出一种简单有效的方法来制备兼具轻薄、耐酸/碱、高阻燃、优异耐久和高强度的纤维素隔膜,对促进纤维素材料在锂离子电池隔膜中的应用,以及能源行业和环保事业的发展都具有重要意义。
参考文献:
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