Periodic Reporting for period 3 - COBRA (CObalt-free Batteries for FutuRe Automotive Applications)
Reporting period: 2022-10-01 to 2024-06-30
COBRA addresses the main shortcomings of xEV batteries that are now in the market by enhancing each component in the system holistically. The COBRA battery cells will be fabricated using electrodes containing no cobalt without compromising capacity and nominal voltage. The new components will allow rapid cell charging and enhanced safety at a reduced cost. At cell level, the main target is to maximize energy density and integrate smart sensors to improve safety. The battery pack will be constructed using sustainable and recycled materials, and the advanced BMS will ensure optimum battery performance and an extended lifetime for the system. The COBRA project will allow the development of European technology for generation 3b of Li-ion batteries, with an improved performance (electrochemical, economic, and environmental) that could be exploited at an industrial scale shortly after the project’s completion. The COBRA project is important for society in many aspects, including 1) decarbonizing road transport, 2) the production of innovative and sustainable materials and processes for battery production that can be easily adapted to production lines, 3) the reduction of CRM, especially Co, to improve aspects related to energy security, “conflict mineral” vs “ethical supply chain”, and toxicity associated to current Li-ion batteries, 4) reduce dependency on foreign suppliers 5) validate a cost-effective and sustainable technology for the end-user and 6) fulfill energy and power demands associated to xEV of the near future. Regarding COBRA objectives, COBRA will develop a Co-free Li-ion battery technology, demonstrate it at TRL6 (battery pack), and validate it on an automotive EV testbed. At the component level, the main objectives are as follows: a) high discharge capacity and fast C-rate discharge capacity for the cathode, b) useful cycle life of 2000 cycles and withstand high C-rates for the anode, c) stable electrolyte operation at > 4.5 V, d) energy density of at least 750 Wh/l at cell level, e) develop an advanced BMS including smart sensors, f) a more sustainable battery pack with improved characteristics, g) testing and validation of the battery pack for xEV applications and h) attain >95% recyclability of metals at large scale and avoid the use of Co by 100%.
Optimized Li-rich Co-free cathodes deliver a high discharge capacity of 250 mAhg-1, fast charging at 3C, and capacity retention of 65% after 800 cycles. Cathode water processing yielded results comparable to NMP-based processing. Silicon samples were recycled from different sources and tested as composite anode with graphite. Optimized anodes deliver 650 mAhg-1 at C/3 and 438 mAhg-1 at 3C. Several compositions with LiFSI salt and (flame-retardant) additives were formulated and tested as electrolytes, leading to a more stable SEI formation for the anode. Best-performing compositions, including ionic liquids, were formulated as a polymer electrolyte and implemented into coin cells. Selected battery cell components were upscaled and implemented into prototype pouch cells of 23 Ah for characterizations and module assembly; this was achieved by combining optimizations during processing with studies on voltage range, capacity ratio, and cell activation at full cell coin cell level. Cell assembly was conducted using a semiautomatic cell production line, which allowed manufacturing developments to be implemented, including thinner current collectors and the integration of smart sensors for improved safety. The fabrication steps, electrolyte filling and formation, were also optimized during the project. BMS innovations, including integrating sensors, wireless communication, and advanced models and algorithms, have been developed and validated at the battery pack level. The pack designed has sustained 3C charging rates, and prototype COBRA pouch cells have shown higher voltage windows than current generation 3 solutions. The battery pack fabrication included light and strong components with green and recycled materials, and its design targets easy battery disassembly for 2nd life: the pack sustained fire for more than 30 min., and a weight reduction higher than 50 % to steel with better tensile strength per kg. Testing activities were defined according to market needs and electric vehicle standards to validate the battery packs. Environmental and sustainability studies have demonstrated that the recyclability of the battery pack would be 95 %. The use of Co has been completely avoided, showing improvement in LCA and SLCA impacts. In terms of cost, considering the entire lifecycle, the price of the final battery pack was reduced by 33 % compared to the benchmark. The COBRA consortium has published over ten open-access journals, participated in 47 events, and released the Market Intelligent reports, greatly impacting the battery community. The partners are exploring several exploitation pathways, including business case support and continued research in future projects.
Co-free oxide materials with a composite (R+M) structure have been prepared and tested as cathodes for generation 3b batteries. These materials are less toxic and less expensive than current cathode materials, e.g. NMC622 or next-generation NMC811, since COBRA materials do not contain cobalt. Green GEN2 pouch cells were fabricated using water as the cathode and anode solvent. The cathode and a selected electrolyte can be cycled up to 4.7 V, delivering a stable capacity at a laboratory scale. The anode composite fabricated using silicon obtained from recycling e.g. kerf from the photovoltaic industry, shows promising electrochemical results, and to our knowledge, no recycled material has been reported as an anode for generation 3b batteries. The anode delivers high capacity at a 3C rate allowing fast charging for the battery cell. Best-performing electrolyte compositions and new additives to improve safety have been characterized at the coin cell level. Some selected compositions, including ionic liquids, have been selected for polymer engineering, enhancing the cell energy density and safety of battery cells and facilitating the transition towards solid-state battery cells (generation 4). The COBRA project has delivered a battery cell with electrochemical performance in the range of state-of-the-art Li-ion battery cells but without cobalt. The production of these prototype cells will accelerate the implementation of generation 3b battery systems. The fabrication of the cells has been conducted in a semi-automatic assembly line that allows rapid integration and high flexibility for the manufacturing processes, including integrating smart sensors at the battery cell level. The battery pack has been designed with innovative materials that reduce the environmental impact and the system’s weight while increasing its safety, fire resistance, and strength. Moreover, the gas sensor will be placed at pack level to monitor and prevent safety risks. The advanced BMS centralizes the control and safety of the battery and enhances its electrochemical performance. The COBRA project has developed multiple materials and processing innovations, contributing to safety, electrochemical performance, and reduced cost. The recyclability of the full battery pack reached around 95%. The use of cobalt has been avoided 100%, showing improvement in LCA and SLCA impacts.