April 27, 2020
Institute for Materials Research, Tohoku University
Sumitomo Chemical, Co., Ltd.

Tohoku University and Sumitomo Chemical Reveal a New Mechanism
for Preventing Deterioration of Aluminum Anode during Cyclic Battery Reactions

Summary⚫

Discovered that the use of high purity aluminum foil can successfully control the hugevolume expansion/contraction of high capacity aluminum anodes during charge/discharge
processes, and clarified its mechanism.

⚫

Determined that high purity aluminum foil can be an “integrated anode”, which can replace
two components of the conventional graphite anode, i.e., a layered structure of carbon
material (that accommodates lithium ions) and copper foil (that functions as a substrate tocollect current) as it plays the roles of both components.

⚫

Contributed to higher performance and significant simplification of the battery
manufacturing process.

Abstract
Research Assistant Professor Hongyi Li and Professor Tetsu Ichitsubo et al. at Institute forMaterials Research, Tohoku University and researchers at Sumitomo Chemical have jointly
undertaken the research and development of novel anodes for higher capacity of lithium-ion
rechargeable batteries since April 2019. This joint research group has successfully elucidated
a new mechanism for circumventing the huge volume strain during charge/discharge battery
reactions with the use of a high purity aluminum foil alone as anode.
Lithium-ion rechargeable batteries consist of four components: a cathode, an anode, anelectrolyte, and a separator film. Lithium ions move between the cathode and anode when thebattery is charged or discharged; when charging, the anode takes in the lithium ions releasedby the cathode, and the reverse when discharging. Carbon-based materials are currently themainstream for anodes. However, the use of silicon or metals such as tin and aluminum, hasbeen considered as promising anode materials for high energy-density batteries because thesematerials can store three to ten times more lithium ions than the same weight carbon-basedmaterials. Despite the higher capacity for absorbing more lithium ions, the application ofmetal anodes has been deadlocked because their huge volume changes (two to four times) can
destroy the anode’s structure.
The joint research group has discovered that optimizing the hardness of high purity aluminum
foils can control volume changes, thereby finding a solution to this long-standing issue. This

www.tohoku.ac.jp

discovery was made possible by integrating the excellent materials science capabilities of theInstitute for Materials Research, Tohoku University and the excellent technologies that
Sumitomo Chemical has cultivated to date through its high purity aluminum business. As theintegrated aluminum anode can dramatically streamline the manufacturing process oflithium-ion batteries, the two organizations expect that this will reduce impacts on theenvironment while allowing for the creation of higher capacity, lighter weight, and lower priced
lithium-ion rechargeable batteries. These research results can also be applied to next
generation solid-state batteries, dual-ion batteries, etc.
Institute for Materials Research, Tohoku University and Sumitomo Chemical will continue theirjoint research efforts toward practical implementation of the integrated aluminum anode andcontribute to the development of a sustainable society.
Technical details⚫

In the charging process, optimization of the hardness of high purity aluminum foil enables
uniform insertion of lithium ions across the entire foil surface.

⚫

After the formation of uniform layer of aluminum-lithium compound (AlLi) across the entire
front surface, a concentration gradient is formed between the surface of the foil and theinterior, due to the tolerance of off-stoichiometric composition in that intermetallic compound,even though the ratio is not one-to-one. This causes aluminum element within the foil tomove toward the surface uniformly across the entire face, ensuring that expansion only
occurs along the thickness dimension of the foil during charging (lithium insertion).

⚫

In the discharging process, lithium ions are extracted from the side of the aluminum-lithiumcompound electrode foil that has expanded in the charging process due to the insertion oflithium ions. The remaining aluminum shrinks moderately to form a columnar-porous
structure, which efficiently accommodates lithium ions again for the next charge process.

⚫

The bottom of the aluminum foil remains intact, serving as a substitute for the copper foil ofconventional graphite anodes, collecting current and maintaining a stable electrodestructure. In other words, the high purity aluminum foil alone can be a two-in-one integrated
anode.

The research was published in Nature Communications (online version, April 13, 2020)
https://www.nature.com/articles/s41467-020-15452-0
Publication details
Journal：Nature Communications
Title：Circumventing Huge Volume Strain in Alloy Anodes of Lithium Batteries
Authors：H. Li, T. Yamaguchi, S. Matsumoto, H. Hoshikawa, T. Kumagai, N. L. Okamoto,T. Ichitsubo
DOI：10.1038/s41467-020-15452-0
Acknowledgements
This work is a joint research project contracted between the Institute for Materials Research at
Tohoku University and Sumitomo Chemical Co. Ltd. This work is partly supported by Grant-inAid for Scientific Research (S) number 18H05249 and Grant-in-Aid for JSPS Research Fellow
number 18J11696 commissioned by Japan Society for the Promotion of Science (JSPS).

Contact◆Further research information
Structure-controlled functional materials
Institute for Materials Research, Tohoku University
Professor Tetsu Ichitsubo
TEL +81-22-215-2372
tichi@imr.tohoku.ac.jp◆MediaInstitute for Materials Research
Tohoku University
Misa Tomimatsu
TEL +81-22-215-2144
pro-adm@imr.tohoku.ac.jp

Sumitomo Chemical
Corporate Communications Dept.
Takahiro Suzuki
TEL +81-3-5543-5102
sumika-kouhou@ya.sumitomo-chem.co.jp