Batteries with soil and cement as electrolytes
MetadataShow full item record
This work has shown for the first time the feasibility of a soil-based battery. Moreover, it has shown for the first time the feasibility of a cement-based battery with set cement as the electrolyte, zinc as the anode and manganese dioxide as the cathode. This work has also shown the feasibility of batteries with the electrolyte being continuous throughout the anode, cathode and electrolyte. The soil-based and cement-based batteries of this work are monolithic and can either be portable or be parts of a structure. This unconventional application of soil and cement is enabled by the water present in both materials and the ionic conductivity of water. Soil and cement are also attractive for their low cost and environmental friendliness. In contrast, conventional liquid electrolytes are a source of pollution and conventional solid electrolytes are expensive. A battery of this thesis comprises anode component, electrolyte component and cathode component, each of which involving either soil or cement as a continuous constituent, such that (i) the soil or cement constituent in the system consisting of anode component, electrolyte component and cathode component is continuous essentially throughout the system, (ii) the soil or cement constituent in the anode component, electrolyte component and cathode component provides the electrolyte function, (iii) the electrolyte component consists of either soil or cement, (iv) the anode component comprises either soil or cement and an active component (e.g., zinc) that is necessary for the electrochemical reaction that occurs at the anode component, (v) the cathode component comprises either soil or cement and an active component (e.g., manganese dioxide) that is necessary for the electrochemical reaction that occurs at the cathode component, and (vi) the anode component and the cathode component are completely separated by the electrolyte component. The active component in the anode component is dispersed in the anode component; the active component in the cathode component is dispersed in the cathode component. The design, preparation and testing of soil-based and cement-based batteries are provided in this thesis. Soil-based batteries are superior to cement-based batteries in performance, due to the higher ionic conductivity and higher relative dielectric constant of soil. The soil-based battery exhibited longer battery life, greater capacity, and higher consumption of active components. The soil-based battery was able to be discharged under a constant current up to 10 mA (current density = 125 μA/cm 2 ), providing power output up to 24 μW/cm 2 , whereas the cement-based battery could only attain 120 μA (current density = 3.8 μA/cm 2 ), providing power output up to 1.4 μW/cm 2 . Although the open-circuit and running voltages of the soil-based battery were lower than those of the cement-based battery (28 days of curing), the former had a greater capacity (23 mAh) than the latter (0.3 mAh) at similar weights and volumes.