With researchers testing different materials for a fresh take on the battery, how should we assess whether a certain material is a viable option? Integrating materials like silicon, graphene, and even sodium into battery chemistries is currently being studied. Here are 5 factors to consider when assessing whether a certain battery material is feasible.
- Material cost
Material costs greatly affect the feasibility of using a certain material within batteries. With batteries so heavily relied upon nowadays, and demand only continuing to grow, choosing the right materials to keep prices low is imperative.
In 2010, a lithium-ion battery pack cost more than USD1000/kwh. This dropped significantly to USD156/kwh by 2019, and is projected to drop below USD100/kwh in the coming years.
The reducing cost of the battery has allowed more and more people to buy into batteries as a permanent energy solution for large applications such as electric vehicles or grid storage, facilitating the shift towards clean energy.
However, certain materials commonly used within lithium-ion batteries contribute to the high cost of the battery. For instance, cobalt is pricey and its cost tends to fluctuate due to limited supply and high demand. The case is similar for nickel. As the supply of these metals tend to be concentrated in certain parts of the world -- the Democratic Republic of Congo for cobalt, and Indonesia for nickel -- their prices would be dependent on the export policies of these countries.
- Abundance and sustainability
The abundance and supply of a material not only affects its price but also long-term sustainability. Some analysts predict that the supply of the rare metals used in current batteries could deteriorate in just a few years. Industry insiders project that there would be a shortage of cobalt by 2022. In order to support the increasing demand for batteries, researchers are searching for alternatives.
One such alternative is sodium. Sodium is the sixth most abundant element on earth -- comparatively, lithium is the 25th. This means the sodium is a strong rival to lithium in terms of long-term availability. The sodium-ion battery is potentially cheaper and easier to produce than its lithium-ion counterpart, though there is still much to improve upon before it becomes a solid contender in terms of energy density.
For now, graphite is the preferred anode material, but much research is being put into silicon as a cheaper alternative. Silicon is the second most abundant element in the earth’s crust, making it a good choice for future batteries.
- Material deterioration
However, just because a material is abundant, it doesn’t mean it is necessarily suitable to use in a battery. While silicone is a favored substitute, many researchers have found that silicon tends to deteriorate quickly when used in a battery. Although its capacity is theoretically higher than graphite, the silicon anode tends to swell almost 300% when receiving ions. This causes the anode to crack and deteriorate, thus quickly reducing the energy density of the battery.
Different materials react differently in different combinations. For instance, although energy dense, pure lithium metal reacts negatively with the electrolyte and promotes the growth of dendrites as ions deposit unevenly on the surface of the anode. When assessing battery materials, its reactivity and long-term performance needs to be taken into consideration.
The safety of the battery is a key concern. The dendrites formed inside the battery could potentially pierce the separator and cause the battery to short-circuit. Moreover, although lithium-ion batteries are generally stable, they have also been known to catch fire or combust when damaged. This is largely due to the flammability of the liquid electrolyte used inside the battery. Semi-aqueous or solid-state electrolytes are viable replacements to create a safer battery.
- Environmental impact
In large quantities, certain materials are toxic to the environment. Cobalt and nickel are currently being used in lithium-ion batteries, however there are long-term environmental impacts associated with them, especially without proper disposal or recycling measures.
With the large number of batteries reaching end-of-life and being disposed of, heavy metals can accumulate and pose a safety hazard to people and the environment. If improperly disposed, these heavy metals can leak into the ground and water supply and affect the health of people and animals.
How materials are extracted from the environment and the effect this has should also be taken into account. Lithium mining has been found to cause habitat destruction and pollution, and damages the soil of surrounding agriculture operations.
Alternatively, the process of extracting sodium is much more environmentally friendly, another reason why it is a favorable option.
Each material has its pros and cons and these should all be measured when assessing its practicality. As batteries seek to facilitate a greener and cleaner future, the processes which this is achieved should also be examined. Sustainability should be considered alongside cost and battery chemistries in order to find balanced and viable alternatives for batteries.