Researchers at IBM and vehicle OEM Daimler have used a quantum computer to help them design next-generation lithium-sulfur batteries.
Scientists used quantum hardware to calculate the dipole moment of three lithium-containing molecules for lithium hydride (LiH) using four qubits— a basic unit of quantum information— on IBM’s Q Valencia quantum computer.
The team simulated the ground state energies and the dipole moments of the molecules that can form in lithium-sulfur batteries during operation. These were: LiH, hydrogen sulfide (H2S), lithium hydrogen sulfide (LiSH), and lithium sulfide (Li2S).
The research was published in their paper ‘Quantum Chemistry Simulations of Dominant Products in Lithium-Sulfur Batteries’.
Q Valencia was used to calculate the dipole moments of LiH (and simulated the other three) to understand the electronic distribution in a molecule across its different atoms as bonds are broken.
In a statement, Jeannette Garcia—senior manager for Quantum Applications, Algorithms and Theory— at IBM Research said: “This is crucial— for instance, in the case of LiH, the dipole changes as the nuclei are separated, making the molecule change from being polar (ionic) to neutral.
“Also, while the molecular bonds are stretched, the molecular system must be described by a highly ‘entangled’ state.
“The impact of this entanglement is visible in the dissociation curve for LiH, and without applying the error mitigation techniques, developed by IBM, there is a noticeable bump in the middle of the curve at around 2.5 angstroms. We have applied the same error mitigation techniques in our recent work on Li–S batteries.”
To make sure our calculations on the hardware were accurate, we also performed them on a classical computer using the IBM quantum simulator.