Northvolt, a battery company founded in 2016 in Sweden, manufactures the world’s greenest lithium-ion batteries by managing the supply chain to reduce the transport distance of raw materials, using hydroelectricity to power the gigawatt factory, and making batteries from spent batteries.
Challenges: lithium battery
As road transportation is responsible for approximately 16% of human-made carbon dioxide (CO2) emissions, electric vehicles could significantly lessen this environmental burden. Rapid expansion of electric vehicles increases demand for lithium-ion batteries. The global production of lithium-ion batteries was around 154 GW h in 2017 and could exceed 2,000 GW h by 2028. However, the production and disposal of lithium-ion batteries today are not at all environmentally friendly.
The mining and refining of essential battery materials produces sulfur dioxide and nitrogen oxides, which contribute to environmental issues such as acid rain and smog. Transporting of raw materials and energy-intensive manufacturing processes cause copious carbon dioxide emissions. In addition, 95% of spent batteries today end up in landfills, which poses a risk of toxic chemical leaching.
Northvolt Technology
Northvolt could manufacture lithium-ion batteries that emit 60-70% less carbon dioxide than comparable batteries. Northvolt accomplishes this in three ways: (1) by locating its mining and refining operations nearby; (2) by utilizing hydroelectricity to power its factory; and (3) by recycling used batteries to create new ones.
Refine raw materials close to where they are mined
The mining, refining, and transportation of the cathode materials, such as lithium, nickel, manganese, and cobalt, are reportedly responsible for 30% of the battery's greenhouse gas emissions. Therefore, the manner in which these raw materials are supplied to battery manufacturers is crucial in determining the eco-friendliness of their batteries.
Northvolt deals directly with mining companies and refiners. For example, Northvolt's lithium is derived from spodumene ore mined in Australia and Canada and refined into lithium hydroxide at plants located near these mines. Northvolt can avoid transporting the vast majority of the ore's mass by locating the mining and refining operations nearby.
Hydroelectricity powers gigawatt factory to make batteries
Northvolt’s batteries use the most recent generation of cathode material, with an 8:1:1 ratio of nickel to manganese to cobalt (NMC) to keep the high energy density but maintain the stability and cycle life. NMC batteries power Nissan Leaf, Chevy Volt, and BMW i3 and their demand is growing.
However, the production of NMC 811 batteries is difficult, partly because the cathode’s reactive nickel ions are extremely sensitive to moisture. These cathodes with a high nickel content are considerably more difficult to manipulate because they have to be mixed and coated in extremely dry conditions. Factories are required to operate a portion of their production lines in large, climate-controlled dry rooms, which increases the total energy consumption of the process.
All the steps involved in transforming ore and other raw materials into typical NMC-based Li-ion batteries emit approximately 42 kg of carbon dioxide per 1 kW h of capacity, with approximately 40% of those emissions occurring during cell manufacturing. The Northvolt gigawatt factory, powered by hydroelectricity, should avoid almost all of that carbon dioxide.
Manufacture batteries from used batteries
Northvolt has developed its own hydrometallurgical method for recycling used batteries to make new ones. The hydrometallurgical process uses significantly less energy than pyrometallurgy, and many of the recycling reagents can be reused. Utilizing hydroelectricity to power the process will further improve the sustainability of Northvolt's recycling procedure.
1. Solution discharge of cells and modules for battery recycling
The batteries are crushed prior to the hydrometallurgy process. Discharging the batteries is crucial for safety reasons because spent batteries have "voltage rebound." Voltage rebound can occur minutes to hours after a battery is discharged to 0 V, and the voltage of the battery can rise to 2.5 V or higher. This is extremely dangerous when the cell is being crushed, as the anode and cathode materials could come into contact, resulting in a short circuit or self-ignition. For safe crushing, a deep discharge to a voltage between 0.5 V and 0 V is required.
Northvolt develops a solution discharge process for the deep discharging of used lithium-ion batteries that allows for the safe, fast, low-cost, and effective discharging of batteries to a low voltage of about 0 V and, at the same time, allows for the effective prevention of the voltage rebound to greater than about 0.5 V. The solution discharging process includes the following steps: