Imidazole-buffered acidic catholytes for hybrid Li–air batteries with high practical energy density

• Imidazole-buffered acidic solution has been explored as the catholyte
• Imidazole provides high stability to the solid electrolyte
• Up to 6 M HCl can be used as the catholyte, providing a high energy density
• A facile recycling process facilitates large-scale applications

Hybrid Li–air batteries with acidic catholyte offer high cell voltage and are stable with CO2 in air. However, the practical capacity of the acidic catholyte is limited by the low concentration of acids utilized and the limited solubility of the discharge products. Only weak acids or diluted strong acids with limited practical capacity are generally used due to the poor stability of the solid electrolyte in low pH solution. We show here the pH of high-concentration, strong acids can be increased to near neutral values by forming a buffer with imidazole additive, which can be used in hybrid Li–air batteries. With the addition of 6.06 mol L− 1 of imidazole to 6 mol L− 1 HCl, the solution has a mild pH of ~ 5.0, facilitating the operation of hybrid Li–air batteries with high practical capacity and stability.

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