Industry, academia and governments alike have poured immense resources into improving Li-ion technology—and they’re getting more and more creative. Automaker Mercedes-Benz and quantum computer company PsiQuantum, for instance, are developing novel computational techniques to optimize battery chemistries.
Quantum Battery Simulation
Lithium-ion batteries consist of four main components: cathode, anode, electrolyte and separator. Each of these components must be optimized to create a high performance battery for demanding applications such as EVs and energy storage systems (EESs).
Mercedes-Benz R&D teamed up with PsiQuantum to determine a way to optimize Li-ion electrolytes, the medium that transports positively charged ions between a battery’s cathode and anode. Designing efficient, high performance electrolytes requires a deep understanding of the underlying chemical processes.
To this end, the researchers proposed simulating the chemical reactions in liquid Li-ion electrolytes at the molecular level. However, because such simulations are too demanding for classical computers, the researchers instead proposed using quantum computers, which exploit the strangeness of quantum mechanics to accelerate certain types of calculations, such as quantum chemistry.
The two organizations published their research last month in Physical Review Research, titling their paper “Fault-tolerant resource estimate for quantum chemical simulations: Case study on Li-ion battery electrolyte molecules.”
Understanding the Electrolyte
An electrolyte is a chemical solution inside a battery that allows an electrical charge to pass between the two electrodes. For a battery to be efficient and stable, its electrolyte should have high ionic conductivity, should not react with electrode materials, and should be resistant to temperature changes.
Depending on the type of battery, the electrolyte can be a liquid, solid-state substance (gel), or dry polymer. A variety of solutions, such as soluble salts, acids and bases, can be used as electrolytes.
A common electrolyte in Li-ion batteries is the salt lithium hexafluorophosphate (LiPF6) and solvent ethylene carbonate (EC). Electrolytes can also be enhanced with the use of different additives, such as fluoroethylene carbonate (FEC). The researchers proposed simulations with these components.
Taking Advantage of Quantum Computers
When a salt is placed in a solvent, its components dissociate into ions in a process called solvation. The researchers proposed that quantum chemical simulations would calculate the dissociation energy required for solvation in two different solvent environments, one with additives and one without. The goal would be to determine which environment is more suitable for dissociation.
This case study is but one example of how future researchers could better understand Li-ion electrolytes. Understanding the interactions between the three electrolyte components—salt, solvent and additive—can provide insight into optimizing all types of electrolytes, according to the researchers.
“Quantum chemical simulation can be used to understand the electrochemical reactions that occur in these constituent molecules and thus aid in designing better electrolytes,” the researchers wrote in their paper.
A Path Forward
Ultimately, the crux of the research was not to determine the efficacy of a specific electrolyte additive, but rather to understand the cost and requirements of simulating quantum chemical reactions. The researchers claim that their study is a step toward better understanding how the power of quantum computing can be harnessed to solve real-world problems—like optimizing battery electrolytes—that are classically intractable.
“Quantum computers are expected to enable quantum chemical simulation from first principles—with fewer assumptions and approximations—and thus accurately model the properties of various molecules. In turn, such studies may lead to new insights into those molecules that are otherwise difficult to obtain,” reads the paper.
So, while EV manufacturers won’t yet be cramming their vehicles with quantum-optimized Li-ion batteries, keep an eye on this space. Quantum computers are starting to show real promise, and if this study is any indication, that promise may soon be put to use in the transition to renewable energy.