Separability of Common Lithium-ion Battery Cathode Particles from Graphite Particles by Dielectrophoretic Filtration

• Black mass particles display varied behaviour in dielectrophoretic filtration. • Dielectrophoretic separation of graphite particles is greater than cathode particles. • Separation of cathode particles remain low in black mass mixture separation. In material recycling processes, bulk material shredding commonly results in complex particle mixtures of various size fractions. Traditional particle separation methods based on size exclusion, density and magnetic differences struggle to separate components of the finest particle fraction. This hampers full material recovery from valuable waste streams, e.g. shredded lithium-ion batteries (LIB), waste electronic and electrical equipment (WEEE) and mining tailings. Dielectrophoresis (DEP) is an electrokinetic force experienced by polarisable particles in non-uniform electric fields. Particles show different DEP behaviour depending on their size, shape and composition. DEP offers a chemical-free selective separation method to aid recovery of valuable components in shredded material wastes. In this paper, the separability of particles found in shredded LIB waste is investigated using DEP. Common LIB particles are evaluated including graphite, lithium nickel manganese cobalt oxides, lithium nickel cobalt aluminium oxide and lithium iron phosphate. The effect of DEP conditions (voltage, frequency, medium conductivity) on the particle trapping rate of each battery material was analysed. Graphite particles demonstrated the highest particle trapping rate compared to cathode particles of similar size. Varied DEP behaviour of anode and cathode particles suggests they are separable based on conductivity differences. The effect of graphite on cathode separability during DEP filtration was investigated using anode/cathode mixtures in which cathode particle trapping rates remained low even in the presence of graphite. This work presents DEP as a potential particle separation candidate for LIB recycling as well as other complex microparticle waste streams.