Lithium-ion battery technology is changing our lives, driving the proliferation of electric vehicles such as cars, buses, and trucks. Even mining companies are starting to consider using electric vehicles at mine sites as an economic and environmentally friendly alternative to traditional vehicles. Establishing a reliable, diversified supply of lithium is a top priority for battery suppliers and vehicle manufacturers. The demand is growing at such a rapid rate that technologies to recycle lithium are being pursued.
A related project, reported by Mining.com, focuses on how to best reclaim battery electrodes. The $1-million project, called RecycleMat, is led by the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW). Its ultimate goal is to prevent bottlenecks in the supply chains of cobalt, lithium and natural graphite and to mitigate price risks.
“Future demand for lithium-ion batteries for electric vehicles and for short-term storage of green electricity will surely be enormous,” Margret Wohlfahrt-Mehrens, who heads up Accumulators Materials Research at ZSW, said in a media statement. “The development of a recycling concept to recover as much raw material from spent batteries as possible can be decisive to the sustainable supply of these resources and could considerably reduce the amount of material and energy required for new cells.”
According to Wohlfahrt-Mehrens, the team working at RecycleMat is investigating how to best extract lithium, nickel, cobalt and natural graphite from spent batteries and recondition the electrode material for direct reuse in new lithium-ion batteries or as an intermediate product for battery material synthesis. The scientists plan to validate their processes and resulting products with industry partners.
However battery materials are sourced, manufacturing lithium-ion batteries is complex, and battery manufacturers need reliable technologies to ensure the quality and consistency of their products. Critical to the advancement of the battery is the emergence of higher quality separator film, the coating of separator film for higher efficiency, and the coating of the anode and cathode. Measurement and control systems are specifically designed to increase the quality and performance efficiency of lithium-ion battery separator film, electrode coating and electrode calendering production lines. These systems offer sensor accuracy, reporting capabilities, and innovative techniques to ensure efficient production of high-quality, reliable battery products.
Separator film is one of the key components of a lithium-ion battery. It is a thin but permeable layer of film used to separate the anode from the cathode and prevent short-circuiting while facilitating the flow of charged ions. Separator films are produced either by a dry or wet process to create the required micro porous structure. Therefore, consistent thickness of the film and homogenous distribution of the pores are necessary to optimize the performance and life of the battery. Additionally, separator film can be coated with ceramic or another material to improve efficiency. Thickness sensors offer advanced non-nuclear measurement technology, an ideal solution for measuring the thickness of separator film.
Continuous or patch coating on an aluminum substrate for the cathode or on a copper substrate for the anode is an expensive and challenging operation. Uneven coating of the cathode or anode will result in poor construction of the battery. Even worse, it could create a hotspot lowering the efficiency of the battery, shortening its lifespan, increasing charge time and the risk of thermal runaway. Furthermore, coated products are not recoverable. A basis weight sensor is the ideal sensing technology for accurately measuring the coatings on the cathode and anode, controlling and perfecting the process, and improving yield and quality.
After the electrode coating is controlled to the proper coat weight, the electrode material is calendered for homogeneous thickness and particle size. Pressing the ingredients of a composite electrode improves electrical contact and adhesiveness, and assures the desired geometric and electrochemical characteristics. Proper coating thickness measurement and calender control is critical not only to avoid excessive calender pressing, which could destroy the porous nature of the electrode, but also to provide final dimensional accuracy and essential product attributes in this important process step.