By now, we can hopefully all agree that producing sustainable energy from renewable sources is something humanity should strive for. Though it’s taken us way too long to get started, great leaps have been made in that direction over the last decade.
However, the main energy challenge of the 21st century is not making it sustainably. That part is easy. Storing that energy is hard and expensive. This is where new and improved batteries come in. As we try to “beat” climate change, they will become ever-more important by helping to move cars, trucks and the power sector away from oil, coal and natural gas.
New battery technologies take many forms, and the world has not yet decided which technology will be the winner. Below is short a primer on the most promising ones.
How do batteries work?
It’s impossible to understand the below without basic engineering knowledge.
Electricity is produced by electrons traveling from point A to point B. This movement creates an electrical current which can then be harnessed to power everyday objects. In batteries, point A is a “negative electrode” called the anode, and point B is a “positive electrode” called a cathode.
Because batteries are not directly connected to a power source, they need a way to create electrons so they can travel. This is done thanks to “electrolytes”. This substance interacts with the anode, producing electrons and ions (you need both for balance). The electrons travel and produce power, while the ions are released into the electrolyte to balance the charge at both ends of the battery.
When we recharge a battery, the chemical reaction that occurred during use is reversed. Pretty simple, right?
Lithium-ion Batteries
Lithium-ion is the technology used in the majority of electric cars, PCs and mobiles today. In these batteries, the anode is generally made of either graphite (lower costs), carbon or silicon (the supposed best option), while the cathode is typically made of a lithium-cobalt or lithium-nickel compound. These batteries have a high energy density, and low self-discharge, which is why they’re so widespread. A lot of Lithium-ion batteries varieties exist. Lithium iron phosphate (LFP) batteries, for example, offer worse performances, but are cheaper and safer.
Despite their benefits, most lithium-ion batteries are safety hazard as they contain flammable electrolytes. If they are damaged or incorrectly charged, this can lead to explosions and fires. They are also expensive: today, these batteries can make up a quarter to a third of the cost of electric cars.
Safety and costs are not the only downside to this technology : components from batteries come from mining, which is extremely harmful to the environment. There are also sociological and political aspects to the issue. Cobalt, for example, comes from the Democratic Republic of Congo, where it is mined by Chinese-financed companies or by freelancers who sometimes employ children. Lithium mining harms Argentinian and American natives. The nickel industry, meanwhile, relies heavily on Russian suppliers. Other options need to be explored.
Lithium-sulfur Batteries
As the name indicates, Lithium-Sulfur batteries still use lithium, but at least do away with cobalt. They instead use sulfur to make up the batteries’ cathodes.
As such, these batteries lower environmental impacts and manufacturing costs while reducing the battery’s weight and providing high energy density. In fact, Li–S batteries offer twice the amount of energy per kilogram than Li-i batteries use.
For all these reasons, Lithium–sulfur (Li-S) batteries may commercially replace lithium-ion cells in the future.
Metal-Air Batteries
A metal–air battery uses an anode made from pure metal and an external cathode of ambient air. As the battery is discharging, the anode is going through oxidation (losing electrons), while oxygen is reduced in the cathode to induce a current flow.
The specific capacity and energy density of metal–air batteries is higher than that of lithium-ion batteries, making them a prime candidate for use in electric vehicles.
Aluminium–air and Lithium-air batteries are the most promising metal-air batteries. They have the highest energy densities of all batteries. They are however not widely used because of high costs. They also tend to be single-use (non-rechargeable). This has restricted their use to mainly military applications. However, a car with aluminium batteries has the potential for up to eight times the range of a lithium-ion battery with a significantly lower total weigh. As such, investments in research seem to be worth it.
Sodium-Ion Batteries
The sodium-ion battery (NIB or SIB) is (very) similar to the lithium-ion battery, but uses sodium ions as the charge carriers instead of lithium.
In fact, lithium, cobalt, copper and nickel are not strictly needed to make sodium-ion batteries. As such, this type of battery has received a lot of interest over the past decade because of the uneven geographic distribution, high environmental impact and high cost of these elements (as mentioned earlier). The largest advantage of sodium-ion batteries is the high natural abundance of sodium (salt is cheap). This would make commercial production of sodium-ion batteries far less costly than lithium-ion batteries.
There are however many challenges to mass adoption : these batteries have low energy density, and a limited number of charge-discharge cycles. Nevertheless, they may yet have a future as lithium-ion complements for lower-quality products.
Nanowire Batteries
Regardless of the chemical make-up of future batteries, a nanowire battery would increase the surface area of the electrodes in contact with the electrolyte, thereby increasing the anode’s power density and allowing for faster charging and higher delivery.
Nanowires are usually made of silicon, which tends to expend and damage the battery. In 2016, however, researchers at the University of California, Irvine announced the invention of a nanowire made of gold, capable of over 200,000 charge cycles without any breakage. The technology could lead to batteries that never need to be replaced in most applications.
Solid-State Batteries
The batteries above use liquid electrolytes, which cannot be compressed. The Holy Grail, as such, is solid-state batteries — batteries with solid electrolytes. They would first and foremost improve safety levels: solid electrolytes are non-flammable and will work it harsher environments, unlike their liquid counterparts. Secondly, it permits the use of new materials (such as carbon or glass), enabling denser, lighter, 3D batteries with better shelf-life. Moreover, at system level, it will bring additional advantages such as simplified mechanics as well as thermal and safety management. As the batteries can exhibit a high power-to-weight ratio, they may be ideal for use in electric vehicles.
Challenges however abound, especially if mass adoption is the goal. These batteries are difficult to mass-produce, and are very expensive. This isn’t surprising, as this is the trend for all new technologies.
Many of these technologies are not new at all. Lithium-ion and Lithium-sulfur batteries, in fact, were first developed in the 60s. But as our needs and manufacturing capabilities evolves, so do our interests in various battery technology.
Whatever the best technology, NextGen batteries will need to be cheaply produced at a large scale, with manufacturing capacities we do not have. They will need to have a long life-span to avoid them ending in landfills after a couple of charges. They will also be dependent on the chargers we use, a technology the still needs to evolve. We’ve got our work cut out for us.
Good luck out there.
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