Development of sustainable purification methods for natural graphite and spent graphite for battery use
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
Arina auditorium (TA105), Linnanmaa campus
Topic of the dissertation
Development of sustainable purification methods for natural graphite and spent graphite for battery use
Doctoral candidate
Master of Science Venla Rantala
Faculty and unit
University of Oulu Graduate School, Faculty of Technology, Research Unit of Sustainable Chemistry
Subject of study
Chemistry
Opponent
Professor Saeed Chehreh Chelgani, Luleå University of Technology
Custos
Docent Sari Tuomikoski, University of Oulu
Environmentally friendly purification of natural and recycled graphite: a step towards more sustainable battery materials
A doctoral dissertation conducted at the University of Oulu presents new, environmentally friendly methods for purifying both natural and recycled graphite for use in lithium-ion batteries. Graphite is the most important anode material in lithium-ion batteries, but its availability and production methods are associated with significant challenges. The research offers solutions that could reduce dependence on imported raw materials and promote the circular economy of battery materials.
Graphite is classified as a strategic critical raw material in the European Union, as its supply chains are vulnerable and demand is growing rapidly, for example, due to the electrification of transport. Natural graphite is mainly produced in China, often using environmentally harmful methods. The production of synthetic graphite, on the other hand, consumes large amounts of energy. At the same time, the number of spent batteries is increasing, and the graphite they contain, typically around 22% of the cell mass, remains largely unused in current recycling processes. Industrial recycling mainly focuses on valuable metals. However, under the Critical Raw Materials Act, by 2030, at least 10% of the annual consumption of strategic raw materials should be covered by extraction within the European Union, and at least 25% by recycling.
The dissertation developed sustainable purification methods for both natural graphite and graphite recovered from spent lithium-ion batteries. The results show that graphite can be purified effectively without the use of harmful chemicals. The key results are:
• Natural graphite can be purified without halogens by combining sulfuric acid leaching and a short high-temperature treatment.
• Metallic impurities in spent graphite can be removed using an acid mixture method, that enables simultaneous removal of multiple impurities while avoiding harmful halogens.
• Remaining impurities can be removed by a short high-temperature treatment, which also repairs structural defects caused by battery use and recycling processes.
The study demonstrates that graphite purification can be carried out in a more environmentally friendly way using both primary and secondary raw materials. This opens up opportunities to increase graphite production in Europe and to advance circular economy solutions, where battery materials are given a new lease of life.
Graphite is classified as a strategic critical raw material in the European Union, as its supply chains are vulnerable and demand is growing rapidly, for example, due to the electrification of transport. Natural graphite is mainly produced in China, often using environmentally harmful methods. The production of synthetic graphite, on the other hand, consumes large amounts of energy. At the same time, the number of spent batteries is increasing, and the graphite they contain, typically around 22% of the cell mass, remains largely unused in current recycling processes. Industrial recycling mainly focuses on valuable metals. However, under the Critical Raw Materials Act, by 2030, at least 10% of the annual consumption of strategic raw materials should be covered by extraction within the European Union, and at least 25% by recycling.
The dissertation developed sustainable purification methods for both natural graphite and graphite recovered from spent lithium-ion batteries. The results show that graphite can be purified effectively without the use of harmful chemicals. The key results are:
• Natural graphite can be purified without halogens by combining sulfuric acid leaching and a short high-temperature treatment.
• Metallic impurities in spent graphite can be removed using an acid mixture method, that enables simultaneous removal of multiple impurities while avoiding harmful halogens.
• Remaining impurities can be removed by a short high-temperature treatment, which also repairs structural defects caused by battery use and recycling processes.
The study demonstrates that graphite purification can be carried out in a more environmentally friendly way using both primary and secondary raw materials. This opens up opportunities to increase graphite production in Europe and to advance circular economy solutions, where battery materials are given a new lease of life.
Created 4.6.2026 | Updated 4.6.2026