E-Mobility Engineering 015 l EMotive Scarab off-road truck dossier l In Conversation: Giulio Ornella l Hall effect and magnetic sensors focus l Challenge of batteries for heavy-duty EVs l Alpha Motor Corporation digest l Automated charging insight l HVAC systems focus

TheGrid Fromblackmass to high-purity cobalt Reference design aimed at e-bikes Aqua Metals has demonstrated a key step in using recycled elements in the production of lithium-ion cells for EVs (writes Nick Flaherty). The company, based in Nevada, has successfully plated high-purity cobalt and produced manganese dioxide from lithium-ion battery black mass. Black mass is the result of the recycling process of lithium-ion battery cells and packs (see EME 11, Autumn 2021), and typically includes a range of elements. It has already recovered lithium hydroxide, copper and nickel using a hydrometallurgical refining process that Efficient Power Conversion (EPC) has developed an inverter reference design based around an integrated gallium nitride (GaN) chip that reduces the size of powertrains in electric bikes and other urban vehicles (writes Nick Flaherty). The design, for a 1.5 kW three-phase brushless DC motor drive inverter, uses the EPC23101 eGaN chip. This has an embedded gate driver function and a floating-power GaN FET with an on resistance of 3.3 mΩ RDS(on). The design, called the EPC9173, operates on an input supply of 20- 85 V and can deliver a peak current of up to 50 A. This voltage range and power level makes it suitable for motor drives in e-bikes, scooters and city cars. It contains all the necessary circuits to support a complete motor drive inverter, including gate drivers, regulated auxiliary power rails for housekeeping supplies, voltage, temperature and current sensing, and protection functions. The board in the EPC9173 measures 130 x 100 mm and includes a 40-pin connector to provide power, PWM signals and analogue feedback signals between reuses the chemicals that extract the elements into the black mass. It uses modular systems called Aqualyzers that generate ultra-pure metal one atom at a time. The company, which already recycles lead-acid batteries, supplies the Aqualyzer equipment and services, and is looking to license the technology to recyclers. The ability to plate cobalt and produce manganese dioxide means the process can recover all the high-value metals from used lithium-ion batteries at bench scale. This is leading to the the interface control board and the EPC9173. There are versions for multi- phase DC-DC conversion topologies including Buck, Boost, half-bridge, full- bridge and LLC. The GaN chip operates at up to 250 kHz, higher than for a silicon driver and power switch, which reduces the deadtime in the motor drive control to less than 30 ns. This helps to increase the efficiency of the motor with lower distortion for lower acoustic noise, lower current ripple for reduced magnetic loss, lower torque ripple for improved precision, and lower filtering for lower cost and a smaller footprint. deployment of a lithium-ion recycling pilot that will begin operating later this year, and the company is looking for commercial partners for the technology. The recovered metals can be sold immediately or processed into battery cathode precursor materials for lithium- ion batteries in existing production lines. “We expect that at the early pilot stage, we will be able to recycle 6-10 t of lithium-ion black mass per month, with the goal of scaling up to 1000 t of annual production by the end of 2023,” said Steve Cotton, president and CEO of Aqua Metals. The EPC9173’s smaller size enables the drive to be incorporated into the motor housing and support low- inductance, higher power-density motors. When configured for a frequency of 100 kHz, the size of the input filter and the number of capacitors can be reduced, eliminating electrolytic capacitors from the board. The reference design enables phase current sensing and leg shunt current sensing. EPC provides full demonstration kits, which include interface boards that connect the inverter board to the controller board development tool for fast prototyping. RECYCLING INVERTERS EPC’s inverter reference design is based around a GaN chip to reduce powertrain sizes 8 Autumn 2022 | E-Mobility Engineering