Grain boundary engineered aluminum current collector for energy-dense initially anode-free sodium metal batteries

Abstract The initially anode-free sodium metal batteries represent promising candidates for high specific energy and safe battery systems, relying solely on cathodic sodium reservoirs. However, the irreversible accumulation of electrochemically inactive “dead” Na and unstable solid electrolyte interphases fundamentally constrains cyclability through rapid active Na depletion. Here, we utilize a grain-boundary gallium-rich polycrystalline aluminum current collector to trigger controlled dissoluti