在现代新材料的快速发展中，用节能、省时、低成本和简便的新型方法制备具有优良机械性能和热学性能的轻质、低密度和高孔隙率气凝胶十分必要。在本工作中，我们使用短切电纺聚酰亚胺（PI）纤维作为支撑骨架，通过开发出一种无需特殊干燥方法的真空干燥（VD）与冷冻-萃取相结合的方法，制备出高性能PI 纤维气凝胶（PIFAs）。所得PIFAs 具有低密度（≤52.8 mg⋅cm⁻³）和高孔隙率（>96%）。该PIFA在至少20 000 次的循环压缩过程中展现出高度的耐疲劳性及低能量损失系数。密度为39.1 mg⋅cm⁻³的PIFA具有40.4 mW⋅m⁻¹⋅K⁻¹的热导率。通过进一步使用聚硅氮烷对PIFAs复合改性后，其具备更强的耐火性和氮气氛围中的高残留率（>70%）。这些优异的性能使PIFAs 及其复合材料成为可应用于建筑工业、航空和航天工业轻质材料、隔热和防火层以及高温反应催化剂载体的可选材料。此外，本工作中提出的冷冻-萃取/VD法因其节能、省时和节约成本而可被拓展用于制备其他材料。

In the rapid development of modern materials, there is a great need for novel energy-saving, time-saving, cost-saving, and facile approaches to fabricate light, low-density, and high-porosity aerogels with excellent mechanical and thermal performance. In this work, a freeze-extraction method combined with normal vacuum drying (VD), using short electrospun polyimide (PI) fibers as a supporting skeleton, was developed to prepare high-performance PI fibrous aerogels (PIFAs) without the need for a special drying process. The resulting PIFAs exhibit low density (≤ 52.8 mg·cm^–3) and high porosity (> 96%). The PIFAs are highly fatigue resistant, with cycling compression for at least 20 000 cycles and a low energy-loss coefficient. A thermal conductivity of 40.4 mW·m^–1·K^–1 was obtained for a PIFA with a density of 39.1 mg·cm^–3. Further modification of the PIFAs with polysilazane led to enhanced fire resistance and a high residue (> 70%) in a nitrogen atmosphere. These excellent properties make PIFAs and their composites promising candidates for lightweight construction, thermal insulating, and fireproof layers for the construction industry, aviation, and aerospace industries, as well as for high-temperature reaction catalyst carriers. In addition, the proposed freezing-extraction/VD approach can be extended to other material systems to provide savings in energy, time, and costs.