To successfully meet the United Nations’ Sustainable Development Goals (SDGs), we need significant breakthroughs in clean and efficient energy technologies. Central to this effort is the development of next-generation energy storage systems that can contribute towards our global goal of carbon neutrality. Among many possible candidates, high-energy-density batteries have drawn particular attention, as they are expected to power future electric vehicles, grid-scale renewable energy storage, and other sustainable applications.
Lithium-oxygen (Li-O2) batteries stand out due to their exceptionally high theoretical energy density, which far exceeds that of conventional lithium-ion batteries. Despite this potential, their practical application has been limited by poor cycle life and rapid degradation. Understanding the root causes of this instability is a critical step toward realizing a sustainable and innovative energy future.
In a recent study, a Tohoku University research team led by Dr. Wei Yu (FRIS) Professor Hirotomo Nishihara (AIMR/IMRAM), and first author Zhaohan Shen (JSPS Fellow (DC1)) - with researchers from Gunma University, Kyushu Synchrotron Light Research Center, Manchester Metropolitan University (UK), and the University of Cambridge (UK) - addressed this long-standing challenge by synthesizing a high-purity (> 99%) 13C-labeled graphene mesosponge (13C-GMS).
“Graphene mesosponge is a hollow-structured material with sponge-like properties, such as high flexibility,” explains Nishihara, “It has a unique structure that makes it useful for many different applications. In this case, we customized it to learn more about why batteries fail,”
This novel material, with high surface area and few edge sites, serves as a stable scaffold for loading polymorphic ruthenium (Ru) catalysts. By integrating quantitative characterization techniques and theoretical simulations, the team was able to clearly distinguish whether battery failure originates from carbon cathode degradation or electrolyte decomposition.
The results show that while reducing charge potential helps to suppress carbon cathode degradation, different Ru crystal phases induce varying degrees of electrolyte decomposition.
“Our findings allow us to point out the ‘weakest link’ in batteries – either the cathode or the electrolyte – which lets us know exactly what we need to improve to make Li-O2 batteries a more practical option,” explains Yu.
This breakthrough not only resolves a key controversy regarding the role of solid-state catalysts in Li-O2 batteries but also contributes to the global pursuit of sustainable energy storage solutions. By revealing the hidden mechanisms behind battery failure, the research provides new design principles for next-generation batteries that can support SDGs and accelerate innovation in clean energy systems.
The findings were published in Applied Catalysis B: Environment and Energy on September 29, 2025.
This work was supported by JST ASPIRE (grant no. JPMJAP2309); JST A-STEP Grant no. JPMJTR22T6; JSPS KAKENHI (grant nos. 24K17761, 22K14757, 21K14490 24KJ0436 and 24K08038); EPSRC (EP/X042693/1, EP/X035859); UKRI Future Leaders Fellowship (MR/T043024/1).