SnO2@carbon-nanocage interconnected framework for high-performance sodium metal batteries

Sodium metal batteries (SMBs) are regarded as a promising alternative for large-scale energy storage due to the abundance and low cost of sodium. However, the development of SMBs primarily hampered by considerable volume expansion and the gradual pulverization/agglomeration of sodium-affinity sites. These issues cause irreversible damage to the framework and lead to excessive current concentration at the agglomerates, which in turn triggers uneven sodium deposition and sodium dendrites growth. In this work, a novel carbon/SnO 2 composite sodium-plating framework (SnO 2 @DCF) is prepared by first constructing a defective carbon-nanocage interconnected framework (DCF) and subsequently encapsulating SnO 2 nanoparticles within the nanocages. Specifically, the defective carbon-nanocage interconnected framework, provides more Na + migration pathways and buffers volume expansion of sodium metal. Meanwhile, the SnO 2 nanoparticles maintain good dispersion in nanocages during cycling, offering abundant nucleation sites and thus facilitating uniform sodium nucleation. The synergistic effect between DCF and SnO 2 realizes dendrite-free sodium deposition, yielding excellent electrochemical performance, such as a low initial sodium nucleation overpotential of only 5.3 mV, minimal voltage hysteresis, and stable cycle behavior for 60 min at 1 mA cm −2 .