Scalable Manufacturing of Multilayer Electrodes with Integrated Ceramic Separators for Improved Safety, Increased Energy Density, and Reduced Cell Assembly Cost

EnPower, Inc. is a Li-ion battery manufacturing and technology development company that uses a slot-die roll-to-roll (R2R) coating process in which multilayer electrodes are produced. We plan to leverage its multilayer technology to simultaneously coat ICS separator on electrodes, thereby decreasing the number of components to be assembled, substantially increasing cell safety, and improving rate performance. This project aims to replace the polyolefin free-standing separator (FSS), an essential component of a Li-ion cell, with an integrated ceramic separator (ICS). Commercially available FSSs fundamentally contribute to the thermal runaway progression in the event of a cell failure. As temperature increases, FSSs shrink, resulting in direct anode-to-cathode contact. Even state-of-the-art (SOA) FSSs that are coated with a ceramic material cannot prevent rapid shrinkage during internal short-circuits. Additionally, polyolefin separators are limited in porosity to maintain tensile strength, and they limit assembly speed and cell thickness to maintain cell processability. During Phase I, EnPower advanced the manufacturability and tested performance of ICS technology on both anode and cathode, as well as built prototype cells without an FSS. With some ICS formulations, multiple R2R slot-die coatings were produced, with consistent, low ICS loadings and thicknesses comparable with common separators. Rate capability and life cycle tests were performed on cells with multiple ICS formulations, capacities, and layer architectures. Compared to reference cells, cells with ICS electrodes showed similar performance, even at a 3C discharge and 3C charge rate (on separate cycles). Nail penetration testing was performed to test ICS on anode and cathode individually. In the case of the ICS cathode cell, no smoke was generated, and voltage was stable after penetration (EUCAR 3). This Phase II proposal has four goals. Ľ Further develop formulation for a lower ICS density and a more electrochemically beneficial microstructure and thermal conductivity Ľ Develop the process for separator free cell assembly and demonstrate performance surpassing the baseline Ľ Develop a quality process for electrode defect detection for ICS coatings Ľ Demonstrate cell repeatability and safety to move towards commercialization By building on our proven technology and results obtained from our Phase I period, EnPower will advance ICS technology readiness and target to commercialize advanced Li-ion cells by 2025. The cells developed will both be applicable to aerospace and automotive markets, with licensing possible as well due to minimal additional equipment. The developed cell will be safer while maintaining fast charge and high power capability.