Fending Off Oxygen Release Leads to Safer High-Energy-Density Lithium-Ion Batteries

A fresh insight has been given by a research group in the way safe high-energy-density batteries can be realized with the release of oxygen in lithium-ion batteries.

Having discovered that the higher the energy density of the battery, the higher the possibility of battery overheating that may have the end result of explosion of battery, and to achieve the United Nations Sustainable Development Goals, batteries that store more energy should be developed to help carbon neutrality.

It is known that the Oxygen that comes out of a active cathode material would trigger thermal runway, leading to overheating, the knowledge to deal with this occurrence appears limited, it is on the aegis of this that Researchers from the Tohoku University and the Japan Synchrotron Radiation Research Institute (JASRI) stepped in to this challenge, studied the behaviour of oxygen release, together with the relating structural changes of cathode material for lithium-ion batteries LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111). NCM111 acted as a model oxide-based battery material through coulometric titration and X-ray diffractions.

The team found out that the NCM111 component infuse 5 mol% of oxygen release without decomposing and also discovered that with the exchange of Li and Ni, oxygen release induced structural disordering.

It was noted that with the release of oxygen, transition metals, Ni, Co and Mn in NCM111 have the ability to uphold a balanced charge in the materials limited.

The team proceeded to use soft X-ray spectroscopy absorption at BL27SU SPring-8 – a JASRI operated large-scale synchrotron radiation facility in Japan.

The researchers further observed a selective reduction of  Ni³⁺  in NCM111 from the start of oxygen release. With the end of the Ni³⁺  reduction, Co³⁺ decreased, while Mn⁴⁺ remained invariant during 5 mol% of oxygen release.

Takashi Nakamura, a co-author of the paper had this to say about the process:

“The reduction behaviours strongly suggest that high valent NI (Ni³⁺) enhances oxygen release significantly,” To test this hypothesis, Nakamura and his colleagues prepared modified NCM111 containing more Ni³⁺ than the original NCM111. To their surprise, they discovered the NCM111 exhibited much severer oxygen release than expected.

In cognizance of this, the team proposed that the high valent transition metals destabilize lattice oxygen in oxide-based battery materials.

“Our findings will contribute to the further development of high energy density and robust next-generation batteries composed of transition metal oxides,” said Nakamura.

Reference: “Lattice Oxygen Instability in Oxide-Based Intercalation Cathodes: A Case Study of Layered LiNi_1/3Co_1/3Mn_1/3O₂” by Xueyan Hou, Kento Ohta, Yuta Kimura, Yusuke Tamenori, Kazuki Tsuruta, Koji Amezawa and Takashi Nakamura, 23 June 2021, Advanced Energy Materials.
DOI: 10.1002/aenm.202101005