It is very difficult to escape the influence of battery technology in our modern lives. The devices power our phones, tablets, power tools, and vehicles.
Today many people are familiar with the Lithium-Ion Battery, and you might be using one right now. Few people may know that the Lithium battery has been around for forty years, and were first invented by M Stanley Whittingham while he was at Exxon. I wouldn’t search them out on eBay, the first ones were as expensive as they were toxic. It took researchers another decade to remove the hazardous metallic lithium. Then twenty six years ago, the first commercial units were released by Sony.
Fast forward to the present day, nanotechnology is already being utilized in commercially available batteries. One distinguished company producing the batteries is A123 Systems located in Michigan.
The technology was originally developed at the Massachusetts Institute of Technology by professor Yet-Ming Chiang. The nanotechnology is actually a Nanophosphate, and is engineered to replace the conventional phosphates found in the electrodes of batteries. The new phosphate offers the gain of better conductivity and more uniform discharge rate than conventional electrodes. All the magic occurs on the batteries cathode electrode, which is coated in the nanoparticles. The nanoparticles range in size from one-tenth of a micron in diameter to several microns. The clustered particles spread out to a length of several microns and dramatically raise the surface area of the electrode. It is also claimed that the large particles avoid the toxicity of conventional nanotechnologies and are well above the standards established by the Environmental Protection Agency.
One major limitation of conventional batteries is the rate of the chemical reaction. Typical batteries use a process known as “intercalation” that adds or removes lithium ions from the lattice of the battery electrode. This reaction is naturally limited in scale to the rate that ions can be exchanged in the framework. Using Nanophosphates, the surface area is much higher. Once you have a larger surface area, the ions can react with the electrodes at a quicker rate. Since power is the product of voltage times current, substantially higher powers can be realized with these batteries.
Safety is another important consideration in battery design. The original batteries were very toxic devices. Current models are much safer but don’t short-circuit them. Users can also turn their phone into a burner when they puncture the batteries. Please don’t puncture the batteries. The Nanophosphate chemistry greatly reduces the danger by fully transferring the lithium ions. In a conventional Lithium battery, only about half of the lithium ions are transferred between the electrodes. The remaining ions stay in the electrolyte, where the elemental lithium is very reactive. In the event of a puncture, lithium readily reacts with oxygen and ignites. Boom! In the case of short-circuit; excess current can breach the separator dividing the electrodes. With the protection gone, the current quickly rises and heats the electrolyte to ignition.
Heat is another hazard to conventional Lithium batteries. When you heat your phone over an open fire. Don’t place your phone over an open fire. The heat will degrade the electrodes in the battery.
The decomposing chemicals in the electrode release more heat and more oxygen. The oxygen will then combine with the reactive lithium and Bang! Nanophosphates have the advantage of releasing far less oxygen when overheated.
Any user of modern phones might also complain that the battery life declines with age. Part of this is simple chemistry. The electrodes have a habit of degrading after repeated ion reactions with the electrolyte. The diminished electrode chemistry ultimately reduces the capacity of the battery. This can be really irritating when the cell loses a quarter of its capacity. Once this happens, the cycle life for the cell can be considered spent. In the tests, the Nanophosphate did much better.
There is one last aggravation with conventional batteries that most people may not be aware of. It is the specific energy of the cell. Specific energy is the total energy of a battery divided by its mass, which would then be joules per pound or joules per kilogram depending on the units chosen. Unfortunately, joules are difficult to measure without exploding the battery. Don’t do that. Power is far more convenient to measure, and it is the rate at which the battery discharges. Making this more difficult, it is a practical impossibility to completely discharge a cell. The specific energy should then be best expressed as the usable specific energy. I digress; battery engineers have to allow for this in their designs. Maximizing the usable specific energy could make a very explosive battery. Designers can lower the danger by lowering the energy. There are other reasons for lowering the usable energy. The energy of the cell is proportional to the range of voltages that the battery can operate under. Using wider voltage ranges mean higher energies but at the consequence of a shorter battery life. Engineers can build more life into a battery simply by restricting the voltage range of the device. When batteries are cycled more shallowly, the electrodes suffer less corrosion. Then there is the problem of designing the cells to deliver a steady current throughout the voltage range. The more deeply the cell is discharged, the less consistent the output current. There is also the problem of the usable energy of the battery; it steeply falls once the cell reaches the lowest voltage range. Since Nanophosphates can tolerate much higher powers than conventional electrodes, the specific energy of the unit is also increased.
Put down the phone. In the end, Lithium-Ion batteries are as useful as they can be dangerous. In the present day, the hazard can be contained in our mobile devices.
In the coming years, Lithium batteries are expected to go mainstream in automobiles and even the electric grid. In the absence of improvements to their reliability, it could be disastrous. The batteries have long been notorious for being explosive. Nanophosphate technologies have the capacity to raise the performance while lowering the danger of the batteries.