Fueled by its use in phones, electric cars and other portable electronic devices, Lithium-Ion is the dominant chemistry for reusable batteries on today’s market. The ultralight, power dense battery has seen explosive growth in the past few years, and this growth is expected to continue.
Unfortunately, this growth also means price increases are projected to continue. Lithium prices rose 14 percent from 2015 to 2016, with larger increases across the market. These price increases are compounded by an expensive extraction process and a small number of sites with large quantities of lithium. Currently, the U.S. imports almost all of its lithium from either Chile or Argentina.
These mining operations will need to expand to keep up with increasing demand, and prices are unlikely to drop any time soon. This increasing cost, and a sense of curiosity, leads us to examine other potential chemistries for reusable batteries and solar storage. The most likely alternatives to lithium are sodium-ion and potassium-ion, although many other promising chemistries are beginning to emerge.
A battery’s chemistry dictates its design, which consequently determines its charge, capacity, power density, temperature range, flammability, and other features. Newly emerging chemistries will need to be able to compete with lithium-ion. Namely, they need to be reusable, compact enough for portable applications, and maintain their charge with subsequent uses. Ideally, they would also be less expensive and safer than the notably flammable lithium-ion chemistry.
The Possibilities of Potassium
A recent contender for the chemistry crown, potassium-ion, offers a major price advantage over lithium-ion batteries. Potassium-ion batteries are reusable like lithium-ion, but use a much more available, abundant, and easily processed chemical than lithium. This leads to lower prices.
Recent developmental work on the chemistry suggests that these batteries may also charge more quickly than lithium-ion batteries. From an energy perspective, potassium is not as dense as lithium, so these batteries could be larger.
The larger size of potassium ions led to them taking longer to get through the graphite structure of the anodes. However, recent advancements have led to replacing these anodes with ones made from hollow carbon spheres, potentially increasing the chemistry’s capacity even further. Other research using carbon nanofibers allowed for increasing charging times and reducing battery weight. One of the major challenges for this chemistry will be finding methods to mass produce the more sophisticated anodes, and keeping the batteries compact and energy dense.
Solutions in Sodium
In potassium-ion batteries, a potassium-ion replaces the lithium-ion. An organic compound called myoinositol acts as the cathode, and phosphorous acts as the anode. Much like potassium-ion, sodium-ion represents a potentially cheaper chemistry for reusable batteries and energy storage.
Even more-so than potassium, sodium is cheap and abundant. Additional advantages include the ability to drain to zero charge without damaging the materials inside, unlike lithium which needs to maintain 30 percent of its charge to avoid damage. The chemical nature of sodium also means that it will not catch fire, is non-toxic and potentially water resistant.
Although sodium batteries will likely be larger and heavier than lithium-ion batteries, some companies believe they can make a chemistry with comparable energy densities. The major challenge facing the sodium-ion chemistry is its tendency to oxidize when exposed to air. A solution to this issue, as well as improvements in the electrolyte, the cathode, and the anode are required to get this chemistry into the mainstream.
Although both the sodium-ion and potassium-ion chemistries promise cheaper storage options for solar power in the near future, neither are currently on the market. Further development will be needed before we see lithium-ion displaced. It is interesting to note, however, that due to the presence of potassium and sodium in organic systems, both of these new chemistries have potential applications an entirely new kind of storage – biologically compatible batteries.
Of course, countless other chemistries also offer promising results for storage technology, although most will be in development for a while longer than potassium-ion or sodium-ion. From solid state batteries, to rechargeable zinc, to lithium-air, there is no shortage of emerging energy storage technologies. As lithium costs increase, countless more could continue to emerge.
Kyle Pennell from PowerScout (a marketplace that lets you compare multiple quotes for all your smart home improvement projects) contributed this article.