Lithium ion batteries have become the common high performance batteries we use in many high tech devices. They are readily secondary (rechargeable), contain a high amount of energy versus volume and weight, and have good lifespans. However, as like many technologies, there are limitations for the current iteration. The chemical energy stored by the lithium ion cells can’t seem to exceed between 200 – 300 watt-hours per kilogram (Wh/kg). Being one of the more effective cell types, this leaves us with cell phones that run for 5 hours and stacks of cells powering cars for only 100 miles; all at fairly high expense, due to lithium ion’s relatively high price.
What if there is a cell that could increase the charge stored versus weight as much as 10 times that of lithium ion? There is a young, fledgling cell type out there called lithium air batteries, which could provide such an incredible power increase.
A conventional cell works by chemical process, where chemical energy is converted to electrical energy. Essentially, there are two halves to a cell which are separated by a substance (an electrolyte). The electrical energy is garnered from the chemical redox and oxidation reactions from the anode and cathode on the half cells (the resulting gain and loss of electrons is the flow of electricity). The electricity (ions) now flows through the bridge between the cells (and through the separating electrolyte), creating a constant stream of electricity. It is this process that allows batteries to create electrical energy from stored chemical energy.
Lithium ion batteries, the currently commonly used batteries, use substances with lithium ions in the anode and cathode. However, the chemical reaction taking place during oxidation takes fuel, in a sense, and is depleted over time and needs to be stored in the battery itself. Lithium air batteries, however, use the oxygen in air as an oxidizing agent. The oxygen is stored in the cathode, and reacts to create the flow of electricity. Intrinsically, this is very beneficial. Due to the abundance of oxygen, lithium air batteries (Li-air) do not need to store it internally, freeing up space and weight.
With this reduction in weight and volume comes a large increase in the possible battery charge given in a limited space. With a 10 fold increase, a LI-air battery contains about the same amount of energy as gasoline. This opens it up to being a viable alternative source of energy for the automotive industry (500 miles on a single charge has been IBM’s pursuit), as well as increasing efficiency on a myriad of other devices. A cell phone that holds a charge for a week of use? A possibility.
Li-air batteries are not with detractors, however. General Motors points out that a Li-air battery on a vehicle would require the installation of an air blower and air filtration unit (as lithium cannot make contact with water). GM posits that this would negate any benefit provided by the Li-air battery’s reduction in weight and space, rendering them pointless. Also, chemists predict issues with longevity with Li-air, as the accumulation of substances on the cathode will gradually reduce the space available, limiting the effectiveness of the battery over time.
While the hurdles are present, they do not seem too large in scope, whatsoever. The reduction in complexity of the engine due to it being electric leaves more than enough space for a blower and filtration unit, which can be refined over time, once that becomes the primary obstacle. The science behind lithium, period, is still fairly new. Lithium ion batteries were only introduced into commercial products in 1991, not becoming widely used until the 2000’s, and overcame many issues, including longevity. Already, Li-air batteries are being refined, chemically and procedurally, to be more effective over a duration of time. Without a doubt, Li-air will be the next upgrade in electrochemical cells, provided an even better opportunity doesn’t make itself known.
One issue, however, with the whole premise of lithium becoming such a mainstay in batteries is actually lithium itself. Lithium isn’t rare, by any means, but neither is oil. Lithium can be produced in two fashions; expensively through mining (there were mines in North and South Carolina), or cheaply by extraction from brine in salt deposits. Obviously, the more inexpensive method is more attractive. Where are viable salt deposit locations? Four countries, just four, currently have access to significant amounts of lithium. These countries (China, Chile, Australia, and Argentina), represent 90% of known sources of viably extractable lithium.
If lithium air batteries do happen to become popular and do serve as a functional source of power for vehicles, demand for lithium would be expected to increase. Currently, batteries account for just shy of a quarter of the demand for lithium, meaning a spike in the demand for its use in that category would have a significant effect on its overall demand. Lithium production, while currently sufficient, could be strained by demand if the acceleration of lithium battery technology occurs quickly, leading to a large degree of control over lithium prices by a few countries. Sound familiar? To illustrate the issue, China has recently reduced the amount of rare earth materials it exports, increasing prices globally (as China has the majority of these resources). Barring the possibility that demand could just plain exceed production, prices could easily be set arbitrarily until the cost of buying salt extracted lithium from foreign countries begins to exceed the costs of mining domestically (representing a cost increase of about 2 – 3 fold).
Lithium deserves to be treated as a highly valued resource. Similar to a surge in the value of copper, demand for lithium will have an effect on geopolitics and necessitates a sort of national policy on its procurement. A potential source for lithium, for example, is Bolivia, which American access to is not guaranteed; steps should be taken to insure that a steady supply from such a source is mutually beneficial. Lithium production should also be boosted as much as possible domestically, in places such as salt deposits in Nevada, in order to avert future foreign dependence.
Lithium air batteries hold a significant amount of potential, in both the automotive industry and conventional electronics (where power drain is ever increasing). Just the possibility of a clean car that runs further on a charge then a combustion engine powered vehicle alone makes scientific interest warranted, but the idea of charging a phone once a week is also enticing. We will most likely see degrees of Li-air implementation in the next 5 years or so, meaning a policy regarding the lithium element should be taken in order to prevent future geopolitical turmoil.
–MP
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