Scalable interface-interphase design of tin electrodes enables pouch-type sodium all-solid-state batteries

Tin (Sn) anodes in sodium all-solid-state batteries (NaSSBs) suffer severe chemomechanical degradation and interfacial instability during (de)alloying reactions, which disrupt ion-electron percolation pathways, accelerate interphase degradation, and reduce sodium inventory. Here, we show that rational anode interface-interphase design enables highly reversible (de)alloying with mitigated volume expansion. This architecture is mechanically compliant and ion-electron co-percolating, sustaining Na⁺ diffusion and electron transport while mitigating sodium trapping, thereby enabling reversible electrochemical operation of Sn. The engineered Sn anode achieves a high initial Coulombic efficiency (93.6%), long cycle life (500 cycles), and high loading (5 mAh cm⁻ 2 ) in pellet cells. Importantly, this strategy is compatible with roll-to-roll processing, enabling scalable manufacturing of NaSSBs. The resulting pouch-type NaSSB delivers a stack energy density of 301 Wh L⁻ 1 and sustains over 100 cycles at 3 mAh cm⁻ 2 under 5 MPa. These results demonstrate a viable pathway toward scalable manufacturing of high-energy NaSSBs.