Melilite Complex Oxide Catalyst for Metal-Air Batteries

The patent replaces expensive noble metal catalysts with a cost-effective transition metal oxide catalyst system based on barium strontium cobalt iron silicate/germinate. This substitution uses abundant, inexpensive materials (barium, strontium, cobalt, iron, silicon, germanium) to achieve the desired catalytic function, directly addressing the cost and rarity issue while maintaining high ORR/OER activity through optimized composition ratios and crystal structure

The patent employs a composite catalyst system with multiple transition metal elements (Co, Fe) combined with silicate/germinate components in a specific crystal structure. This composite approach allows synergistic effects between different metal elements, achieving high catalytic activity comparable to noble metals while using abundant, inexpensive materials. The composite structure enables optimization of electronic properties and surface activity for both ORR and OER reactions

The patent modifies the composition parameters of transition metal oxides by incorporating silicate/germinate components and adjusting the ratios of barium, strontium, cobalt, and iron elements. This parameter optimization maintains the beneficial electronic structure for catalysis while enhancing chemical stability. Specifically, the silicate/germinate framework provides structural rigidity and resistance to dissolution in highly alkaline electrolyte, solving the stability issue of conventional perovskite catalysts

Instead of attempting to stabilize perovskite structures that inherently suffer from poor alkaline stability, the patent inverts the approach by adopting a different crystal structure (barium strontium cobalt iron silicate/germinate) that naturally provides both high catalytic activity and exceptional chemical stability. This structural inversion avoids the fundamental stability limitations of perovskite while achieving comparable or superior catalytic performance