Sodium batteries with longer life and insensitive to temperature thanks to a new electrolyte – Technology – Hybrids and electrics

A research team from Pacific Northwest National Laboratory (PNNL) belonging to the United States Department of Energy, has developed a sodium ion battery con a high life cycleovercoming what is the biggest handicap of this technology to replace the lithium batteries. The work focused on change the type of salt circulating in the electrolyte in such a way that it was possible to avoid the slowing down of the electrochemical reactions which maintain the flow of energy.

The perfect battery is impossible to achieve. That’s why a combination of criteria is necessary to balance to try to obtain a product that meets all without being the best in any: safety, energy density, power, life cycle and high percentages of reuse and recycling, all this at the lowest possible cost.

In the case of this last criterion, low cost, sodium-ion batteries are ideal candidates. This material is obtained from the oceans or the earth’s crust and is therefore cheap, abundant and durable. They also offer benefits of operating now at elevated temperatures, as they are not flammable and work well in cold climates. Although they don’t have as much capacity as lithium batteries, when cycled at high voltage (4.5 volts) they can dramatically increase the amount of energy that can be stored in a weight or volume given. However, they give degradation problems during loading and unloadingwhich, until now, has hampered its commercialization.

The The PNNL research team got around this drawback by changing the ingredients that make up the battery’s liquid core. This change avoids the performance issues experienced by sodium-based batteries. The research and its findings have been published in the journal natural energy. The director of the investigation, Jiguang (Jason) Zhanga pioneer in battery technologies with over 23 patented inventions, claims to have demonstrated “that sodium-ion batteries have the potential to be a sustainable and environmentally friendly technology”.

As Zhang explains, in batteries, the the electrolyte is the “blood” which circulates and maintains the flow of energy. It is formed by dissolving salts in solvents resulting in charged ions flowing between the positive and negative electrodes. Over time, the electrochemical reactions that keep energy flowing slow down and the battery stops being able to recharge. In current sodium-ion battery technologies, this process occurs much faster than in lithium-ion batteries.

electrolyte salt sodium ion batteries pnnl-interior
In lab tests, scientists dramatically increased the number of charge and discharge cycles to over 300 with minimal capacity loss (less than 10%) for a coin-sized battery.

The current recipe for sodium ion battery electrolyte causes the protective film on the negative end (the anode) to dissolve over time. This film is critical because it allows sodium ions to pass through, preserve battery life. The technology designed by PNNL works by stabilizing this protective film.

The PNNL team tackled the problem by changing the liquid solution and the type of salt that passes through it to create a new chemical recipe for the electrolyte. The new electrolyte also generates an ultra-thin protective layer on the positive pole (the cathode) which contributes to the additional stability of the whole unit.

In laboratory tests, for the first time, scientists significantly increased the number of charge and discharge cycles (more than 300) with a minimal capacity loss (less than 10%) for the case of a coin-sized pile.

The technology recently developed by PNNL researchers uses a solution that works well as a natural fire extinguishing system that it is insensitive to temperature changes and that it can operate at high voltages. The key to this characteristic is precisely the ultra-thin protective layer that is created on the anode which remains stable once formed, providing an extended life cycle.

Sodium ion battery technology late again vis-à-vis the achievement of a high rate of energy density. However, its advantages, such as resistance to temperature changes, stability and long life, make it competitive with lithium since they are valuable for implementation in light electric vehicles and even for storage of batteries. network energy.

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