COBRA project researchers develop cobalt-free lithium battery for the automotive industry

The Catalonia Institute for Energy Research (IREC), in collaboration with CIDETEC Energy Storage and seventeen European partners, has developed Spain’s first large-format cobalt-free lithium-ion battery prototype. The prototype has been developed through the COBRA (CObalt-free Batteries for FutuRe Automotive Applications) project  and is currently in the pre-commercial phase.

COBRA’s materials, including the Co-free cathode, anode composite, and liquid electrolyte with flame retardant additives or ionic liquids, have been thoroughly benchmarked and characterized for the upscale of the final pouch cells intended for automotive applications.

The chosen materials are:

  • an Al-doped Li-rich LNMO, which delivers a high discharge capacity of 160 mAhg-1 at C/3 and maintains a stable discharge voltage during battery cycling;
  • an anode composite comprising 10.2 wt.% of silicon obtained from waste stream recycling and commercial graphite, providing a capacity of 438 mAhg-1 at 3C; and
  • a carbonate-based electrolyte with additives and anodic stability of ≥ 4.8 V vs Li/Li+

Co-funded with nearly €12 million from the European Commission’s Horizon 2020 program, which runs from January 2020 to July 2024, the COBRA project is manufacturing two hundred cells for the assembly of a complete battery pack. This prototype aims to be scalable in the medium-term, facilitating the path towards commercialization for manufacturers.

The prototype’s development stage is rated between levels 5 and 6 on the Technology Readiness Level (TRL) scale, which assesses the maturity of a technology. Level 1 represents the most basic form, and level 9 indicates the demonstration phase. <>/p>

The next-generation battery pack incorporates a novel Battery Management System (BMS) that integrates wireless communications within the battery system, new sensors, and advanced algorithms. The communication link relies on optical signals, making it immune to electromagnetic interference.

At the cell level, a set of smart sensors measures temperature, swelling (strain gauge), voltage, and impedance (EIS), while also performing passive balancing. At the module level, a pressure sensor detects venting episodes. Additionally, a laser-based gas sensor located at the battery pack level detects any gas formation within the pack.

These sensors generate data that is utilized by a set of advanced physics-based models to optimize battery operation. An algorithm based on EIS calculates the core temperature of the Co-free cells, while a thermal state observer estimates the temperature distribution of the cells.

Combined, these measurements enable a charge management control to compute the optimal charging profile, minimizing degradation effects such as lithium plating. Enhanced equivalent circuit models with physics-informed parameters are employed at the BMS level to improve the accuracy of State of Charge (SoC) estimation. The pressure and gas sensors provide early alerts and help prevent thermal runaway events.

All these systems operate on a decentralized BMS, which can be used in electric vehicles and grid-connected applications during the second life of the battery, both in a battery pack and single module configuration, thanks to its modular and scalable nature. The battery pack is constructed using green and recycled materials (such as pre-treated wood and aluminium) that are fire-resistant, reducing the weight and environmental impact of the battery system.

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