Achieving multi-dimensional Li plus transport nanochannels via spatial-partitioning in crystalline ionic covalent organic frameworks for highly stable lithium metal anode

The fragile solid electrolyte interphase (SEI) and anisotropic dendrite growth during Li plating/stripping have posed as intractable handicaps to the practical implementation of lithium metal batteries (LMBs). The Li+ uniform distribution and unimpeded transfer play significant roles to enable protuberance-free Li textures. Herein, the highly-crystalline TFSI- ionic-covalent organic framework (I-COF) endowed with designated mixeddimensional channels was constructed as an artificial SEI layer via anionic post-modification. Benefiting from the desirable spatial-partitioning effect triggered by nanochannels reconfiguration, the I-COF with expanded multi-dimensional Li+ transport channels and scaled-down pore volume could effectively disperse the local concentration gradient of Li+ flux and inhibit growth of Li dendrites. Besides, the coordinated TFSI- anions with a high tLi+ of 0.76 can selectively restrict the delivery and decomposition of homogeneous ions. To understand the interfacial charge transfer mechanisms, the lithophilic properties and the energy barriers for Li+ migration were also calculated. Correspondingly, the I-COF(TI-) modified Li|Li symmetric cell showed superb durability over 5500 h at 4 mA cm-2 with extraordinary overpotential. The Li|S full cell also displayed prolonged lifespan and excellent rate performance. The comprehension of the mixed-dimensional interfacial strategy via spatialpartitioning provides new insights into the fabrication of solid-solid interfaces, which can aid in the improved design and development of advanced lithium-metal batteries (LMBs).

Automated summary

The highly-crystalline TFSI-ionic-covalent organic framework (I-COF) with mixed-dimensional channels was constructed as an artificial solid electrolyte interphase (SEI) layer. It effectively disperses the concentration gradient of Li+ flux and inhibits dendrite growth, enabling uniform distribution and unimpeded transfer of Li+. The mixed-dimensional interfacial strategy provides new insights for the design of advanced lithium-metal batteries.