Gelatin–Organic Acid-Based Biodegradable Batteries for Stretchable Electronics

As the environmental pollution caused by electronic products becomes increasingly severe, the development and application of biodegradable batteries have become more important. Traditional biodegradable batteries are limited by low power output, low capacity, and lack of flexibility and stretchability, restricting their range of applications. Herein, a biodegradable battery made from magnesium–molybdenum electrodes and gelatin-organic acid electrolytes such as lactic acid (LA)–gelatin (gel) and the citric acid (CA)–gelatin (gel) is proposed. The addition of organic acids to the gelatin increases the ionic conductivity of the electrolyte and promotes its reaction with the magnesium electrode, effectively enhancing battery performance. In the experimental results, it is shown that the LA–gel-based electrolyte achieves a maximum conductivity of 2.37 × 10⁻³ S cm⁻¹, while the CA–gel-based electrolyte demonstrates a low activation energy of 11.04 kJ mol⁻¹. The highest open-circuit voltage recorded for the CA–gel-based electrolyte with the Mg anode and Mo cathode is 1.92 V, and the related plateau voltage is around 1.3 V. The maximum power and maximum capacity achieved by the Mg-based battery are 76.8 μW and 1.36 mAh cm⁻², respectively, at 40 μA cm⁻² for LA–gel battery. Moreover, the battery can be stretched to 80% strain while maintaining stable capacity.