New materials could lead to safer and more sustainable batteries

Solid-state lithium batteries have the potential to transform energy storage by offering higher energy density and improved safety compared to today’s lithium-ion batteries. However, their limited lifespan remains a major challenge. To address this, researchers at Luleå University of Technology have developed new materials that can significantly extend battery life.

“Our new materials can be used in cathode and electrolyte to extend battery lifespan and support the development of more environmentally friendly energy storage,” says Jiajia Li, who recently completed her PhD in Energy Engineering at Luleå University of Technology.

Lithium metal batteries are considered a promising solution for future energy systems, offering both higher performance and improved safety. By replacing the traditional liquid electrolyte with a solid-state electrolyte – so-called solid-state batteries – they can operate at higher voltage and with lower risk of fire or leakage. Solid-state batteries with high energy density have great potential in areas such as electric vehicles, stationary energy storage, and portable electronics. With longer range, faster charging, and increased safety, they could play an important role in the green transition and contribute to a more sustainable energy system. However, for solid-state batteries to become commercially viable, the solid-state electrolytes must function reliably in practice – something researchers at Luleå University of Technology are focusing on.

“Solid-state electrolytes have the potential to overcome many of the limitations found in today’s solid-state lithium metal batteries, but their conductivity, long-term stability, and the high interface resistance with electrodes still need to improve before they can be used in real-world applications,” says Jiajia Li.

Jiajia Li, doctoral student in Energy Engineering at Luleå University of Technology.

New materials for improved battery performance

The research focuses on solid electrolytes based on poly(ionic liquids) – plastic-like materials that conduct ions. These materials have both high ionic conductivity and good (electro)chemical stability, which are crucial for reliable battery performance. By adjusting the structure of the materials, the researchers have improved lithium-ion transport and the interface between the electrolyte and other battery components. One of the developed materials enabled stable operation for more than 1,000 charge and discharge cycles without performance degradation – an important step toward longer-lasting batteries.

“Many solid-state lithium batteries start losing performance after just 500–700 cycles, so this is a clear improvement. Our materials also work at higher voltages than is typically possible, making them compatible with high-voltage cathodes,” says Jiajia Li.

The results show that several key challenges in the development of solid-state lithium batteries can be addressed – such as improved interfacial contact between electrolyte and electrode, greater voltage stability, and extended cycle life. This makes the technology more relevant for future use in applications like electric vehicles.

The research team has also integrated cellulose acetate from wood – a renewable material – into the electrolytes to increase both mechanical strength and environmental sustainability. The new materials maintained high performance at voltages up to 4.8 volts, while also contributing to longer battery life.

However, several challenges remain before the technology can be used in commercial products – such as the ability to manufacture the materials at scale and to test them under more realistic conditions, including varying temperatures and fast charging.

“This is an important step forward, but further development is needed before the technology is ready for use in electric vehicles. We need to ensure that the materials perform reliably even under high loading mass active material and in varying environments,” says Xiaoyan Ji, Professor of Energy Engineering at Luleå University of Technology and the principal supervisor and responsible Principal Investigator for the research.

The research is conducted in collaboration with the Institute of Process Engineering at the Chinese Academy of Sciences. Through this partnership, the team has been able to establish advanced testing environments, strengthen doctoral supervision, and promote international knowledge exchange in the field of next-generation battery technology. These results have attracted international attention and have been accepted for publication in leading scientific journals such as Advanced Materials and Nano-Micro Letters.

• Energy Engineering
  
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