Chemists have developed termogalvanic facilities element-based hydrogel, which is capable of efficiently cooling the battery due to the evaporation of water and convert part of the energy into electricity. With such a hydrogel, the scientists were able to lower the temperature of a lithium ion battery at 20 degrees Celsius and produce five milliwatts of usable power. Article published in the journal Nano Letters.
Electric and energy devices, like solar cells, diodes and microprocessors, emit large amounts of heat during its work. This heat is required to withdraw from the source to avoid local overheating, which will reduce the efficiency of the device and its operation. Scientists are trying to solve the problem of combination of removing the excess heat and convert this heat into useful work. Traditional approaches to heat recovery — thermoelectric modules — add extra thermal resistance that impedes the dissipation of heat and increases the temperature inside the unit. But effective heat sinks need high energy fans and pumps. To date, these conflicting processes cannot be achieved.
In recent years, scientists have developed termogalvanic facilities elements as a cheap efficient of heat exchanger. They consist of two inert electrodes and an electrolyte solution between them. For energy conversion meets ion migration in solution and the entropy change in the temperature dependence at the transition of the electron between the redox couple and electrodes. Unlike thermoelectric, in termogalvanic facilities elements of the solvent is necessary only to support ionic transport and redox reactions, and therefore can be removed from the electrolyte without deteriorating the efficiency of thermoelectric processes. On the basis of this solvent it is possible to make an additional thermodynamic cycle, for example, in aqueous electrolytes, the water can evaporate, carrying away excess heat, and condense, restoring its original state.
Jun Chen (Chen Jun) with colleagues termogalvanic facilities have developed a smart hydrogelthat is able to convert excess heat into electricity and due to the evaporation of water to achieve efficient cooling. This alone hydrogel absorbs water from the environment and is fully restored, and the rate of evaporation and condensation, scientists were able to vary through the thickness of the hydrogel and the concentration of lithium bromide. They tested the performance of this hydrogel on the smartphone battery and fixed the cooling 20 degree Celsius in comparison with the battery without the hydrogel.