Pillared MXene with Ultralarge Interlayer Spacing as a Stable Matrix for High Performance Sodium Metal Anodes

Sodium (Na) metal is a promising alternative to lithium metal as an anode material for the next-generation energy storage systems due to its high theoretical capacity, low cost, and natural abundance. However, dendritic/mossy Na growth caused by uncontrollable plating/stripping results in serious safe concerns and rapid electrode degradation. This study presents Sn²⁺ pillared Ti₃C₂ MXene serving as a stable matrix for high-performance dendrite-free Na metal anode. The intercalated Sn²⁺ between Ti₃C₂ layers not only induces Na to nucleate and grow within Ti₃C₂ interlayers, but also endows the Ti₃C₂ with larger interlayer space to accommodate the deposited Na by taking advantage of the “pillar effect,” contributing to uniform Na deposition. As a result, the pillar-structured MXene-based Na metal electrode could enable high current density (up to 10 mA cm⁻²) along with high areal capacity (up to 5 mAh cm⁻²) over long-term cycling (up to 500 cycles). The full cell using MXene-based Na metal anode exhibits superior electrochemical performance than that using host-less commercial Na. It is believed that the well-controlled MXene-based Na anode not only extends the application scope of MXene, but also provides guidance in designing high-performance Na metal batteries.