Modification of lithium nickel oxide cathode material
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
OP auditorium (L10), LInnanmaa
Topic of the dissertation
Modification of lithium nickel oxide cathode material
Doctoral candidate
M.Sc.(Eng) Juho Välikangas
Faculty and unit
University of Oulu Graduate School, Faculty of Technology, Sustainable chemistry
Subject of study
Applied chemistry
Opponent
Professor Georg Garnweitner, Technische Universität Braunschweig, Germany
Custos
Docent Pekka Tynjälä, University of Oulu
Powering the Future: Making Cobalt-Free Batteries Better with Smart Chemistry
As the demand for electric vehicles and portable electronics grows, so does the need for better, cheaper, and more sustainable batteries. One promising solution is LiNiO₂ (LNO) —a high-energy, cobalt-free cathode material that could help reduce battery costs and environmental impact.
LNO can store a lot of energy—up to 272 mAh/g—and works within a safe voltage range. Unlike traditional cathodes that use expensive, critical and ethically challenging cobalt, LNO relies on nickel, making it a more sustainable choice. But there is a catch: LNO is not very stable cathode material during charging and discharging. It tends to go through a phase change (called H2 to H3 transition) at high voltages, which can damage the material and shorten battery life.
This thesis explored how to make LNO more stable and longer lasting by modifying its chemistry and processing. This was done by doping LNO with aluminum (Al), magnesium (Mg), and chromium (Cr) to improve structural stability and by optimizing the synthesis temperature to reduce unwanted mixing of lithium and nickel atoms. Furthermore, washing the material was studied to remove leftover lithium from the surface, which affects performance. A second heat treatment was applied after washing to restore capacity and reduce gas formation. At the end, different charging methods were tested to avoid the damaging H2 to H3 phase change.
The key findings in this thesis were as follows: 1) Aluminum doping allowed for higher synthesis temperatures without increasing defects, and helped suppress the harmful phase transition, 2) Washing improved cycle life but slightly reduced capacity and speed, 3) Secondary heat treatment helped recover lost capacity and reduced gas buildup, which is important for battery safety, and 4) Changing the charging protocol (from constant current–constant voltage to just constant voltage) significantly improved battery life—especially for unwashed materials, which retained 155.5 mAh/g even after 1200 cycles.
These improvements bring us closer to making high-performance, cobalt-free batteries that are safer, cheaper, and more sustainable. With further development, LNO-based batteries could play a major role in powering the next generation of electric vehicles and renewable energy systems.
LNO can store a lot of energy—up to 272 mAh/g—and works within a safe voltage range. Unlike traditional cathodes that use expensive, critical and ethically challenging cobalt, LNO relies on nickel, making it a more sustainable choice. But there is a catch: LNO is not very stable cathode material during charging and discharging. It tends to go through a phase change (called H2 to H3 transition) at high voltages, which can damage the material and shorten battery life.
This thesis explored how to make LNO more stable and longer lasting by modifying its chemistry and processing. This was done by doping LNO with aluminum (Al), magnesium (Mg), and chromium (Cr) to improve structural stability and by optimizing the synthesis temperature to reduce unwanted mixing of lithium and nickel atoms. Furthermore, washing the material was studied to remove leftover lithium from the surface, which affects performance. A second heat treatment was applied after washing to restore capacity and reduce gas formation. At the end, different charging methods were tested to avoid the damaging H2 to H3 phase change.
The key findings in this thesis were as follows: 1) Aluminum doping allowed for higher synthesis temperatures without increasing defects, and helped suppress the harmful phase transition, 2) Washing improved cycle life but slightly reduced capacity and speed, 3) Secondary heat treatment helped recover lost capacity and reduced gas buildup, which is important for battery safety, and 4) Changing the charging protocol (from constant current–constant voltage to just constant voltage) significantly improved battery life—especially for unwashed materials, which retained 155.5 mAh/g even after 1200 cycles.
These improvements bring us closer to making high-performance, cobalt-free batteries that are safer, cheaper, and more sustainable. With further development, LNO-based batteries could play a major role in powering the next generation of electric vehicles and renewable energy systems.
Last updated: 10.6.2025