Cary Pint, right, Andrew Westover and Nitin Muralidharan, who is holding the prototype junkyard battery they created in his left hand. He and Westover are holding bottles of the common household chemicals used in the process. (Daniel Dubois / Vanderbilt University)
Take the old metal waste, put them in a glass jar with soap and water and get a high-performance battery. This philosophy adhere to the researchers from the Vanderbilt University - the creators of a powerful battery-functioning waste of copper and steel.
"Imagine that tons of metal waste, which becomes more and more, could be used to supply renewable energy of the future every year, instead of becoming a burden to the environment and processing enterprises" - says Cary Pint, associate professor of mechanical engineering at the University of Vanderbilt.
Pint led the research team that used pieces of steel and copper - the two most commonly ejected material - to create the world's first battery of these metals. Such a battery can store energy better than conventional lead-acid batteries. According to the charging rate of new development can be compared to the ultra-fast supercapacitors.
The research team, consisting of students and graduates of interdisciplinary programs and Vanderbilt engineering faculty, described her achievement in ACS Energy Letters journal. In their work, scientists have demonstrated the many facets of his art, which allows processing of steel and copper materials of various shapes, sizes and purity for the production of functional components of the battery.
In the resulting battery cell voltage is 1.8V, the power density reaches 20W * hr / kg and power density of up to 20 kW / kg. Battery withstood 5,000 consecutive charging cycles, equivalent to 13 years of daily charging and discharging. As a result of the experiment he retained just over 90% of its capacity.
The answer to the puzzle lies in the performance of such anodization - a widespread procedure build the oxide film by means of anodic oxidation. Most often, it is used to impart strength aluminum and decorative finishes, but the anodization procedure may be used with virtually any metal. This can be done even in the home, although it is not recommended.
In the first phase are carried out preparatory work: the metal surface is polished and polished. Next, the degreasing, often with organic solvents such as gasoline, alcohol or acetone, and alkali treatment (ordinary soap). The next stage - pickling the surface of a concentrated solution of sulfuric acid and potassium bichromate. This is done in order to remove oxides, prevent the application of a new coating. Further, actually, anodizing - oxidation of the metal in the electrolytic solution under influence of a constant current. As the substance, the conductive current and sulfuric acid is suitable, but less concentrated. It is unlikely that you will find him at home, so you can replace the solution of baking soda and salt.
To convert the copper and steel electrodes for functional rechargeable energy storage, room temperature is sufficient. Under her influence, these multicomponent alloys are converted into iron oxide, active in redox reactions, and copper oxide. When waste anodized steel and copper using a solution of detergent and electric current, researchers have discovered that metal surfaces are rearranged in nanoscale metal oxide network which can store and release energy when interacting with aqueous based electrolytes.
The Panel concluded that these areas with nanometer networks explain such a fast charging process and exceptional battery stability. In the creation of batteries made of copper and steel used non-flammable, aqueous solutions of electrolytes, which contain potassium hydroxide - an inexpensive salt, which is used in the production of washing powder.
Prototype of high-performance junkyard battery powering a small light. The researchers next step will be to produce a full-scale version suitable for use in energy-efficient smart homes. (Pint Lab / Vanderbilt University)
Pint notes that when your main goal is to produce materials for batteries improvised so cheap to large-scale production capacity made no sense, you have to approach this as something else than to carry out experiments in a research lab.
"We see that modern society is gradually moving to the" culture of creativity ", where large-scale production of new products gradually scaled up to individuals or communities. So the battery has remained outside this culture, but I believe that day will come when people will be disconnected from the network and will produce its own batteries. This level, which began with the battery technology, and I think that we will be able to return to it "- said Pint.
A team of scientists from Vanderbilt University drew inspiration from the Baghdad batteries - a simple device, invented in 2000 years before the birth of Alessandro Volta. It consisted of a ceramic terra cotta pot, copper sheet and the iron rod, which were found with traces of electrolyte. It is assumed that such a battery is filled with acid or alkali, could create tension in 1B. Scientists over the last century have experimented with this galvanic cell, trying to make an exact copy of the Baghdad battery and reproduce the reaction. The experiments included in the story, were extremely successful. However, some skeptical scientists believe that the fact that this artifact can generate energy, does not mean that it was used just for this. Although the interpretation of this artifact is still a matter of controversy, its simple design has become an example for the creation of a new development. In the future, scientists plan to construct a full-scale prototype of the battery, suitable for use in energy-efficient smart homes.
"With this project we are opening up new horizons, where a positive result - no commercialization, and a clear set of instructions that can be addressed to the general public. This is an absolute rethinking capacity battery, which will help to circumvent barriers to innovation in energy storage and conservation of energy "- says Pint.