The United States develops an environmental protection law for lithium battery manufacturing and recycling to reduce processing costs and energy consumption -Lithium - Ion Battery Equipment
(: Virginia Tech)
The researchers found that the rate performance and cycle life of electrodes fabricated through a water-based process were comparable to electrodes fabricated using traditional solvent-based processes. The use of water-soluble binders enables the use of water to recover cathode compounds from spent electrodes. After successful regeneration of such compounds, the electrochemical performance of the new electrode is equivalent to that of the original electrode.
Mass production of lithium batteries can cause environmental concerns during battery manufacturing and handling. Traditional lithium battery electrodes, especially the cathode, use N-methylpyrrolidinone (NMP) as the solvent and are made by the slurry method. In fact, it is estimated that a battery manufacturing plant with an annual output of 100,000 60kW, 10kWh plug-in hybrid electric vehicle (PHEV) cells uses 4.1 million kilograms of NMP annually to deposit cathode layers. Considering that the global production of lithium batteries is about 400GWh, a large amount of NMP is required.
However, NMP is an expensive regenerated toxic substance that was placed on the idle list by the European Commission in 2018. In addition, in the production process of lithium batteries, about 47% of the energy consumption is spent in the electrode drying process for the evaporation and recovery of NMP solvent. If NMP is replaced with water, a quarter of the energy consumption can be reduced. An additional 29% of the energy is consumed in drying chamber equipment, which is used to control the humidity and temperature of the slurry mixing and casting operations. Therefore, new electrode production processes and/or NMP alternatives need to be developed to reduce processing costs and energy consumption.(Lithium - Ion Battery Equipment)
The researchers replaced NMP with water in electrode production, separated the black material (a mixture of carbon black and active material) from the current collector, dissolved the water-soluble binder in water to achieve recovery, and then separated the active material from the carbon black separated from it and lithiumized again to form battery materials.
The researchers say the water-based processed electrode used in this study has excellent electrochemical properties that are comparable to those made from recycled materials. If some potential challenges can be addressed, this approach could provide a green, sustainable process for manufacturing and recycling lithium batteries.