Battery in the Form of a Soil-Matrix Composite Qiaoli Meng 1 ; Yibadan Kenayeti 2 ; and D. D. L. Chung 3 Abstract: This work has shown the feasibility of a soil-based battery, in which the electrolyte (soil) was continuous throughout the anode, cathode, and electrolyte. The soil contained 49 wt.% water. The battery was in the shape of a soil-based monolithic slab and involved an anode (zinc, particle size 7 μm, acetic acid washed), a cathode (MnO 2 , particle size 40 μm), and an electrically conductive additive (carbon black, particle size 30 nm). A battery was composed of three successive layers: a cathode layer (a soil-matrix MnO 2 particle composite, 12 wt.% MnO 2 , 15 mm thick), an electrolyte layer (soil, 2 mm thick), and an anode layer (a soil-matrix zinc particle composite, 9 wt.% Zn, 5 mm thick). After assembly, it was compacted at a pressure of 1.67 MPa. The soil electrolyte exhibited resistivity of 220 Ω · cm and a relative dielectric constant of 29 (1 kHz). The soil-based battery discharged at 10 mA (0.25 mA=cm 2 ) and exhibited open-circuit voltage up to 0.24 V, initial running voltage up to 0.17 V, power output up to 43 μW=cm 2 , capacity up to 179 mAh, and fraction of zinc consumed up to 0.06. The running voltage decreased continuously during discharge. The soil-based battery was much superior to a previously reported cement-based battery. DOI: 10.1061/(ASCE)EY.1943-7897.0000101. © 2014 American Society of Civil Engineers. Author keywords: Battery; Soil; Zinc; Manganese dioxide; Electrical resistivity; Dielectric constant. Introduction Due to the rising cost of fuel and the environmental pollution (including global warming) resulting from the burning of fuel, there is urgent need for clean and renewable energy, such as that gener- ated by fuel cells, batteries, solar cells, thermoelectric devices, and windmills. Among these sources of energy, batteries constitute the most developed source. However, their limited energy density makes conventional batteries (which are quite small) unable to pro- vide large amounts of energy. For example, a battery-operated car would require the entire trunk of the car to be filled with batteries. As a result, batteries are only used as power sources for small de- vices, such as digital cameras, and the role of batteries in alleviating the energy crisis is small. A battery consists of an anode (the electrode that is an electronic conductor and undergoes chemical oxidation during the discharge of the battery) and a cathode (the electrode that is an electronic conductor and undergoes chemical reduction during the discharge of the battery), which are separated by an electrolyte. During dis- charge, a voltage appears between the anode and the cathode. Batteries and fuel cells suffer from (1) the safety (leakage) and environmental problems associated with the electrolyte in the usual case where the electrolyte is a liquid (Aurbach and Schechter 2004; Blomgren 2003; Nazri 2004; Webber and Blomgren 2002; Wilkes 2003), (2) the poor interface (Edstroem et al. 2004; Ross 2006) between the electrodes (anode and cathode) and the electrolyte and the inadequate room-temperature ionic conductivity of the electro- lyte in cases where the electrolyte is a solid (Notten et al. 2007; Sadoway 2004; Takada et al. 2004), and (3) the limited amount of energy that can be provided due to size and mass limitations. One of the problems of conventional portable batteries relates to the electrolyte, which is an ionic conductor that serves as the medium between the anode and the cathode in a battery. There are two classes of electrolyte: liquid electrolytes and solid electro- lytes. Due to the high mobility of ions in a liquid compared to that of ions in a solid, liquid electrolytes are better for battery per- formance. Furthermore, liquid electrolytes are much less expen- sive than solid electrolytes. In addition, the interface between the electrolyte and an electrode is more intimate when the electrolyte is a liquid rather than a solid. The intimacy of the interface causes the resistance associated with this interface to be relatively low. How- ever, a serious shortcoming of liquid electrolytes is associated with the tendency of leakage of the liquid electrolyte from the battery (Kim et al. 2008) and the environmental pollution that results from this leakage. In addition, a battery containing a liquid electrolyte must be sealed through proper packaging, and the packaging adds to the cost of battery manufacture. Examples of liquid electrolytes are aqueous solutions with dissolved salts. Water is itself an electro- lyte. Examples of solid electrolytes are polymers that have been doped so that they contain ions. Other examples of solid electro- lytes are ceramics that have their ions arranged in such a way that substantial movement of the ions within the ceramic solid is geo- metrically possible. The ionic conductivity of a solid electrolyte increases with increasing temperature. Solid electrolytes tend to have inadequate ionic conductivity at room temperature. Electrokinetics is a tool for removal and supply of matter into or out from porous materials. Electrokinetic transport processes are used in civil engineering for repair and maintenance purposes and in environmental engineering for contaminant removal. Pri- mary examples include desalination of concrete and soil remedia- tion. However, the concept behind this paper is not electrokinetics; rather, it pertains to a battery that uses soil as the electrolyte. Soil is the most abundant material on earth. The use of soil lo- cated in the ground as the electrolyte of a battery, with electrodes (zinc as the anode and copper as the cathode) placed in the ground, 1 Graduate Student, Composite Materials Research Laboratory, Univ. at Buffalo, State Univ. of New York, Buffalo, NY 14260-4400. 2 Associate Professor, Dept. of Civil Engineering, Xinjiang Vocational College of Construction, Urumqi, Xinjiang 830054, P.R. China; presently, Visiting Scholar, Composite Materials Research Laboratory, Univ. at Buffalo, State Univ. of New York, Buffalo, NY 14260-4400. E-mail: yibadat@yahoo.com.cn 3 Professor and Director, Composite Materials Research Laboratory, Univ. at Buffalo, State Univ. of New York, Buffalo, NY 14260-4400 (corresponding author). E-mail: ddlchung@buffalo.edu Note. This manuscript was submitted on October 6, 2011; approved on September 19, 2012; published online on September 22, 2012. 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