Engineering of Covalent Organic Framework Nanosheet Membranes for Fast and Efficient Ion Sieving: Charge-Induced Cation Confined Transport

Covalent organic framework membranes for lithium extraction: facilitated ion transport strategies to enhance selectivity

The surging global demand for lithium, driven by the proliferation of electric vehicles and energy storage technologies, has exposed significant limitations in conventional lithium extraction methods, including inefficiency and environmental harm. Covalent organic frameworks (COFs) have emerged as a promising platform to address this challenge and enable more sustainable lithium extraction, owing to their unique advantages such as precisely tunable pore sizes, robust stability, and the ability to incorporate functional binding sites for selective ion transport. This review focuses on structural design and functionalization strategies in COFs to optimize lithium-ion separation, highlighting how pore confinement effects, tailored interlayer stacking arrangements, and strategic functional group modifications can dramatically enhance Li+ selectivity over competing ions present in brine solutions. A particular emphasis is placed on the fundamental energy barriers associated with lithium-ion transport. In particular, we discuss how appropriately designed pore environments and lithium-binding functional groups reduce the dehydration energy required for Li+ to enter and traverse COF nanochannels, thereby facilitating faster and more selective Li+ conduction. We also survey recent advancements in COF-based lithium separation technologies, such as high-performance COF membranes and sorbents for extracting lithium from brines and seawater, evaluating their potential, as well as remaining challenges, for sustainable industrial implementation. This review provides a comprehensive understanding of how advanced COF engineering can enable efficient and selective lithium-ion transport, offering valuable insights for the development of next-generation lithium extraction materials and technologies.

Linear Enhanced 3D Nanofluid Force-Electric Conversion Device

The inherent trade-off between permeability and selectivity has constrained further improvement of passive linear force-electric conversion performance in nanofluidic pressure sensors. To overcome this limitation, a 3D nanofluidic membrane with high mechanical strength utilizing aramid nanofibers/carbon nanofiber (ANF/CNF) dual crosslinking is developed. Due to the abundant surface functional groups of CNF and the high mechanical strength of ANF, this large-scale integrated 3D nanofluidic membrane exhibits advantages of high flux, high porosity, and short ion transport path, demonstrating superior force-electric response compared to conventional 1D and 2D configurations. The enhancement mechanism of the ANF/CNF membrane is systematically investigated through experimental results and theoretical calculations. The optimized device has a sensitivity of 111 nA cm-2 kPa-1, a response/recovery time of 63/68 ms, and a stability of 45 000 cycles. This study successfully overcomes the inherent performance limitations of traditional nanofluidic membranes, offering promising potential for applications across artificial intelligence, the Internet of Things, and smart wearable devices.