A cathode additive improves lithium-ion batteries

Authors: Maria Diaz-Lopez (Diamond Light Source) , Philip Chater (Diamond Light Source)
Co-authored by industrial partner: No

Type: Diamond Annual Review Highlight

State: Published (Approved)
Published: July 2021
Diamond Proposal Number(s): 20893

Abstract: During the first charging cycles in lithium-ion (Li-ion) batteries, lithium from the cathode material is irreversibly bound at the surface of the anode. This loss of lithium from the cathode reduces the overall cell capacity and limits the battery’s performance. Additives can provide extra lithium ions to the cathode by reacting during the first charge, compensating for lost lithium ions. However, many of these sacrificial cathode materials produce gases, which can be dangerous. Researchers developed a sacrificial cathode additive, made from a nanoscale mixture of Li2O and Li-Mn-O, with outstanding first charge capacities. They monitored the sacrificial cathode reaction during the first charging cycles, using in situ Pair Distribution Function (PDF) on the I15-1 beamline at Diamond Light Source. They made use of the Diamond Radial In situ X-ray (DRIX) electrochemical cell, which is optimised for fast operando PDF analysis. The low and constant background scattering from the DRIX cell provides excellent total scattering data quality, even on nanostructured or weakly-scattering samples. This design allows for a comprehensive understanding of reactions within battery materials including knowledge of the short-range ordering, nanostructures and amorphous intermediates. The study demonstrated that the first charge capacities of Li2O:Li-Mn-O sacrificials are achieved by the electrochemical activation of Li2O. Adding the sacrificial to the battery cathode improved the first charge capacity of LiFePO and LiCoO by 13%.Due to their lowcost, ease of preparation 42 and compatibility with industrial battery fabrication, Li2O:Li-Mn-O sacrificials are highly promising, outperforming currently used additives.

Journal Keywords: Li-ion batteries; In situ pair distribution function; Cation disordered rock-salts; Sacrificial additives

Diamond Keywords: Batteries; Lithium-ion

Subject Areas: Materials, Chemistry, Energy

Instruments: I15-1-X-ray Pair Distribution Function (XPDF)

Added On: 12/11/2021 13:30

Discipline Tags:

Physical Chemistry Energy Energy Storage Materials Science Energy Materials Chemistry

Technical Tags:

Scattering Total Scattering