Researchers from McGill University in Canada recently demonstrated a new degradable battery. Its design is inspired by the "lemon battery" commonly used in middle school science experiments, and uses acidic substances to enhance the conductivity of the electrolyte. The team used gelatin as the electrolyte carrier, combined with organic acids such as citric acid in lemons, to make the battery more environmentally friendly while maintaining good conductive properties.
The battery uses gelatin as the electrolyte and magnesium and molybdenum as electrode materials, both of which are relatively gentle in the soil environment and can safely decompose over time. Researchers pointed out that when magnesium electrodes are used alone, it is easy to form a surface layer that hinders the reaction between the electrolyte and the electrode. Adding organic acids such as citric acid and lactic acid can break this "passivation layer" and significantly increase the voltage and service life of the battery.
After the material system was determined, the team further drew on the Japanese art of "Kirigami" to cut the battery in a specific pattern so that it would form a similar three-dimensional structure when stretched. This structure allows the battery to be stretched in the length direction to about 180% of its original length while maintaining voltage stability, thus adapting to the flexibility and fit requirements of wearable devices and implantable devices in the body.
In order to verify the feasibility of practical application, the researchers produced a simple pressure sensor worn on the finger and powered by this small battery of about 1 × 1 cm. Tests have shown that the battery can drive the sensor stably and its output power is only slightly lower than a standard AA battery, indicating that its power supply capability in micro wearable electronics has practical value.
In terms of environmental friendliness, experiments have shown that when the battery is immersed in a phosphate buffer solution after being exhausted, its electrolyte and magnesium electrode are basically completely degraded in less than two months, while the molybdenum electrode degrades slower but can also decompose over time. The research team believes that this achievement proves that materials such as gelatin and organic acids can be used to build more environmentally friendly flexible batteries, which are expected to reduce electronic waste and heavy metal pollution in future wearable devices, medical implants and Internet of Things terminals.