A Look into Emerging Battery Technologies

The world depends more and more on batteries each year. Nowadays, lithium-ion batteries, a technology that has been around for decades and is also present in gadgets like laptops and smartphones, power the majority of electric vehicles (EVs).

Continuous development has reduced costs and improved performance over time, bringing EV prices closer to those of conventional gas-powered vehicles while enabling them to go hundreds of miles between charges. New applications for lithium-ion batteries include grid-based electricity storage, which helps mitigate the volatility of renewable energy sources like solar and wind.

However, there is still plenty of opportunity for development, labs and businesses alike are looking for methods to improve technology, increase capacity, shorten charging times, and decrease prices. The goal is to develop even cheaper batteries, which will provide cheap grid storage and allow EVs to travel even longer distances on a single charge. At the same time, concerns over the availability of essential battery materials such as cobalt and lithium are driving the hunt for alternatives to traditional lithium-ion technology. In the midst of rising demand for EVs and renewable energy, as well as a surge in battery research, one thing is certain, batteries will play a critical role in the transition to renewable energy. Let’s take a look at some of the emerging technologies.

1. Solid State Batteries

The electrolyte for liquid lithium-ion batteries is a liquid (an organic solvent). While liquid electrolytes can easily enter the cathode/anode and conduct lithium, high temperatures increase the electrolyte's chemical breakdown, and the flammability of organic solvents might result in catastrophes, such as ignition, in the event of a malfunction. The electrolyte in a Solid State Battery, on the other hand, is solid, not volatile or flammable, and is widely regarded as very safe, temperature-resistant, and resistant to deterioration.

Source: Nissan

Liquid electrolytes use organic solvents with low boiling points and high volatility, hence there are temperature constraints for charging. Solid State Batteries, on the other hand, do not need liquid electrolytes, allowing them to operate at high temperatures and provide great fast charging performance. The materials that can be used in liquid electrolytes are limited due to side reactions with the cathode and anode materials, but solid electrolytes have fewer side reactions because they are solid, allowing for more material combinations.

The fundamental problem with solid-state batteries has been their production at scale and at a reasonable cost. However, tremendous progress is being made, with various firms and research institutes collaborating to overcome these challenges. If marketed effectively, solid-state batteries could offer a safer and more efficient alternative to present lithium-ion batteries.

2. Sodium-ion Batteries

Sodium-ion batteries are rechargeable batteries that function similarly to lithium batteries but carry the charge with sodium ions (Na+) rather than lithium ions (Li+). Sodium is a silvery, soft alkaline metal that is plentiful in nature, including sea salt and the earth's crust. The functioning of sodium-ion batteries is extremely similar to that of lithium-ion batteries since the two elements' chemistry is similar.

Sodium-ion batteries are made up of the following components: a negative electrode or anode that releases electrons and a positive electrode or cathode that accepts them.

When the battery is discharged, sodium ions flow from the anode to the cathode via an electrolyte, a material made up of free ions that acts as an electrical conductor, creating the potential difference that generates the current. When the battery is charged, sodium ions return to the anode until a specific voltage is reached. Sodium-ion batteries are a versatile and cost-effective solution since they rely on an alkaline metal that is abundant on Earth and has minimal production costs. They are less toxic than other popular batteries, as they do not require lithium, cobalt, copper, or nickel and can release polluting gases in the event of a fire. And they are adaptable to different uses.

Sodium-ion batteries have a lower energy density than lithium-ion batteries, however, they are still in the early phases of development, with ongoing research aimed at improving their performance.

3. Lithium-Sulfur Batteries

A lithium-sulfur (Li-S) battery is a type of lithium battery that uses lithium as the negative electrode and sulfur as the positive electrode. The working principle of a Li-S battery differs slightly from that of a conventional lithium-ion battery. In traditional lithium-ion batteries (LIBs), lithium ions move from the lithium-containing cathode to the anode during charging and in the reverse direction during discharging. However, in a Li-S battery, the cells are initially in a charged state and begin by discharging.

During discharging, lithium ions move from the lithium anode to the sulfur (or sulfur composite) cathode through a separator soaked in the electrolyte, where sulfur undergoes a multi-step, multi-electron reduction process, forming lithium sulfide (Li₂S). During the charging process, lithium sulfide (Li₂S) is oxidized back to sulfur, releasing lithium ions, which then migrate back to the lithium anode via the electrolyte.

The very low cycle life of lithium-sulfur batteries has been one of their main problems. During charging and discharging, the sulfur cathode degrades significantly, reducing the battery's total life. Nonetheless, new developments in materials and production processes are enhancing Li-S batteries' robustness and functionality.

4. Graphene Batteries

Graphene batteries are a form of battery that includes graphene in the electrodes. The graphene material can enhance the performance of existing batteries, such as lithium-ion batteries, by boosting conductivity and allowing for faster charge and discharge cycles. The large surface area of graphene can also boost the energy density of the battery, allowing for more storage capacity in a smaller space. Despite being a promising material for battery applications, graphene batteries are still under development and have yet to be commercialized on a big scale.

High-quality graphene production is expensive, and scaling up to large-scale applications remains a considerable challenge. Graphene is currently only produced in limited amounts, and the manufacturing technique is still too expensive for mass-market uses.