Self-constructed functional anode for sulfide all-solid-state lithium batteries with ultrahigh critical current density

This work develops a self-constructed functional alloy anode for high-performance all-solid-state lithium batteries (ASSLBs). We designed a (200)-oriented single-phase Li/Na alloy using a controlled weight ratio (0.1:0.9) and a cold-rolling process, with enhanced air stability. When assembled with sulfide solid electrolytes, the Li 0.1 Na 0.9 alloy anode would self-construct into tri-layer functional structures: an in situ formed Na 2 S interfacial layer from the reaction between Na and the electrolyte, to suppress the leakage of electrons at the interface; a self-precipitated Li layer, facilitated by the special orientation, to offer nuclei for the uniform deposition of lithium; and a self-formed Na buffer layer to dynamically regulate the stress during the deposition process. This new anode enables the critical current density of symmetrical cells to exceed 12.74 mA·cm −2 at room temperature, sustaining stable cycling for over 1580 h at 10.19 mA·cm −2 , with the cell-level energy density expected to exceed 450 Wh·kg −1 . We anticipate that this finding will have an immediate impact on the next generation of ASSLBs. • A single-phase Li 0.1 Na 0.9 alloy anode with dominant (200) orientation is fabricated via a facile cold-rolling process and ratio control. • It spontaneously self-constructs a tri-layer functional structure with Na 2 S interfacial layer, Li metal layer and remaining Na buffer in sulfide ASSLBs, addressing interfacial instability. • The anode achieves an ultrahigh critical current density of 12.74 mA·cm −2 and stable cycling over 1580 h at 10.19 mA·cm −2 . • A 70 μm-thick lightweight alloy anode enables a cell-level energy density exceeding 450 Wh·kg −1 , suitable for scalable applications.