Stress-free magnesium anodes enable first 1.07 Ah pouch cell

Researchers in China report a simple solvent treatment that removes damaging oxide layers from magnesium anodes and preserves their microstructure, a combination that helped unlock the first 1.07 Ah multilayer magnesium pouch cell. The result could move rechargeable magnesium batteries closer to commercial use as a higher-capacity, more abundant alternative to lithium-ion.

Why it matters: - Rechargeable magnesium batteries could offer higher volumetric capacity and more abundant raw materials than lithium-ion systems. - Magnesium anodes have been held back by native oxide layers, uneven stripping and plating, and rapid cycle failure. - A scalable anode treatment that stabilizes both surface chemistry and internal stress could remove one of the main barriers to commercial magnesium batteries.

What happened: - Researchers from Chongqing University and Xiamen University reported a protonated organic solvent treatment for magnesium anodes in eScience on June 19, 2026. - The method uses hydrochloric acid and ethanol to replace the native oxide layer with a magnesium ethoxide interlayer. - The treatment preserved a stress-free microstructure and enabled uniform stripping and plating. - The team built the first 1.07 Ah multilayer magnesium pouch cell and reported symmetric pouch-cell cycling for more than 4,000 hours.

The details: - The source problem is the native MgO and Mg(OH)₂ film that forms on magnesium in air or during processing. - That film repeatedly ruptures and reforms during battery operation, which drives non-uniform deposition, low coulombic efficiency, and failure. - Conventional grinding, polishing and acid treatments can damage the metal or remain limited to coin-cell formats. - The team batch-processed magnesium foils up to 150 cm by 10 cm, showing the method can scale beyond small lab samples. - Transmission electron microscopy showed the original 4.6 nm MgO layer became an 8.5 nm magnesium ethoxide layer. - Nuclear magnetic resonance confirmed Mg–O–C bonding. - Electron backscatter diffraction showed the treated anodes kept a stress-free microstructure. - Ground anodes showed stress-concentrated layers about 30 μm deep. - The average kernel average misorientation was 2.05 for ground anodes and 0.18 for treated anodes. - TOF-SIMS showed the magnesium ethoxide interlayer decomposes during cycling and helps form a solid electrolyte interphase with less passivating MgO and Mg(OH)₂. - DFT calculations showed magnesium prefers to strip and plate at grain boundaries. - The dissociation energy at grain boundaries was 0.73 eV versus 1.58 eV on grain interiors. - The adsorption energy was -1.24 eV at grain boundaries versus -0.85 eV on grain interiors. - The grain-boundary-guided mechanism and low-passivation SEI enabled uniform deposition without dendrites. - With Chevrel-phase Mo₆S₈ cathodes, treated anodes delivered 1,500 cycles with 79.8% capacity retention at 0.5 C. - Ground anodes retained 14.4% capacity under the same test. - The pouch cell stacked five cathode sheets and three magnesium foils, reached 1.07 Ah initial capacity, and stayed stable over 50 cycles.

Between the lines: - The key advance is not only cleaner surface chemistry but also stress-free bulk structure, which gives the anode natural grain boundaries for nucleation. - That combination is what makes the work relevant for manufacturing, not just laboratory electrochemistry. - The immersion-based process is compatible with roll-to-roll processing, which matters for industrial scale-up.

What's next: - The researchers say the approach could support larger-format magnesium anodes and more practical rechargeable battery manufacturing. - If scale-up holds, the chemistry could help magnesium batteries compete in grid storage and electric transportation. - The DOI for the paper is 10.1016/j.esci.2026.100609.

The bottom line: - A simple hydrochloric-acid-in-ethanol treatment appears to solve two long-standing magnesium anode problems at once: oxide removal and stress control.