P-Block Compounds Incorporated into SEI Enable Ultra-Stable Cell Cycling in Low-Temperature Sodium-Metal Batteries

Sodium metal anodes (SMAs) are pivotal for high-energy-density batteries but suffer from uncontrolled dendrite growth and interfacial instability caused by infinite volume expansion and a fragile solid electrolyte interphase (SEI). Herein, an innovative strategy is proposed, in which a p-block matrix is in-situ formed from NiTe 2 nanocrystals onto N-doped carbon hollow microspheres (NiTe 2 @NC) during electrochemical activation to overcome these challenges. The p-block matrix with sodiophilic Na 2 Te and conductive metallic nickel effectively reduces the nucleation barrier and establishes bi-continuous ion/electron conduction networks, guiding uniform Na plating. Critically, Na 2 Te dominates the formation of a gradient inorganic-rich SEI with high Young's modulus and low Na⁺ diffusion barrier, significantly enhancing mechanical resilience and ion transport kinetics. Consequently, the NiTe 2 @NC electrode achieves exceptional cyclability (1,000 cycles at 1.0 mA cm − 2 /1.0 mAh cm − 2 with an average Coulombic efficiency of 99.79%). When configured in full-cells with a Na 4 Fe 3 (PO 4 ) 2 P 2 O 7 cathode, it maintains the capacity retention of over 96.1% (103.9 mAh g − 1 ) after 1,200 cycles at 10.0 C. Critically, the full-cell maintains superior electrochemical resilience with high discharge-capacity and >90% retention at low-temperatures (−20 and −40 °C), demonstrating exceptional practicality for sodium metal batteries. This work establishes a new paradigm for stabilizing reactive metal anodes via in-situ-constructed multifunctional interfaces.