Lithium and graphite for battery production: the future of the supply chain
E-mobility is a key component in the shift towards a sustainable transport sector for the future. However, lithium-ion batteries – the main source of power for electric drive systems – will need to be manufactured and recycled responsibly in compliance with ambitious sustainability standards. With the aim of moving towards a cleaner environment and a green economy, it is essential to take a whole-of-supply chain approach.
A new short study by the Oeko-Institut now provides an overview of two raw materials of key importance for current-generation lithium-ion batteries. It outlines the environmental and human health-related challenges associated with lithium mining and the production of graphite.
Lithium: Australia moves into pole position
Lithium is the key element in lithium-ion batteries. In previous studies, the Oeko-Institut has shown that the growing demand for lithium can be met through additional resource extraction and more recycling. Lithium is extracted from two very different sources: from brines in salt flats in South America, and from hard rock mining in Australia. The two production methods differ considerably in terms of their potential environmental impacts.
Lithium extraction from brines in Chile and Argentina has come to public attention and attracted criticism mainly in relation to water scarcity. However, only around one-third of global lithium production now relies on extraction from brines; its significance is therefore declining.
In recent years, Australia has become the largest supplier of lithium, accounting for around two-thirds of global production. The extraction of spodumene – a lithium-bearing mineral – produces wet residues, which are stored in large structures known as tailings storage facilities (TSFs). The breach of a dam at an iron ore mine in Brazil in 2019 showed just how risky this method of storing residues can be unless an effective management system is in place. Alongside robust strategies to ensure the safety of the tailings storage facilities, biodiversity-related issues must be assessed and considered at each individual mining site.
Synthetic versus natural graphite
In all, 96 per cent of anodes in lithium-ion batteries contain graphite as their main material. There are two different types of graphite: natural graphite (NG), which is extracted, and synthetic graphite (SG), which is synthesised by heat treatment of a coke-based precursor. China is now the main supplier of natural and synthetic graphite, both of which have a substantial environmental footprint. For example, the mining of natural graphite produces large quantities of dust, exposure to which can adversely affect the health of workers and local residents, causing breathing difficulties and impaired pulmonary function. Furthermore, the purification of graphite is conducted using inorganic acids which, if not sufficiently contained, can cause environmental damage. One of them is the highly toxic and hazardous hydrofluoric acid.
For the production of synthetic graphite, a carbon source is needed as the starting material, usually originating from the petroleum and coal industry. The process takes several days and requires temperatures over 2500 °C throughout the duration of the treatment. These high temperatures can only be reached in a specialised electric furnace. The resulting emissions depend to a large extent on the energy mix used. An energy mix with the highest possible renewables share is essential in order to significantly improve the environmental footprint for synthetic graphite.
The short study was prepared within the framework of the BMBF joint project Fab4Lib – Research on measures to increase material and process efficiency in lithium-ion battery cell production along the entire value chain.