Improved safety and mechanical characterizations of thick lithium-ion battery electrodes structured with porous metal current collectors

Porous metal current collectors enable the fabrication of thick electrode structures with improved safety margins and unique mechanical properties. Interpenetrating phase composite LiCoO2 cathodes and graphite anodes with large active material loadings are formed using advanced slurry processing techniques with a submersible ultrasonic horn. Full cells with 600 μm thick electrodes demonstrate high aerial capacity of 16.7 mAh.cm−2, improving energy density by 22% with respect to volume versus reference cells using traditional laminate composite electrode stacks. External shorting and nail penetration testing show notably suppressed joule heating currents, limiting peak temperature accrued to just 25% of the reference. Shear testing and three-point bending of individual electrodes and stack assemblies elucidate the greater role of the binder phase in the mechanical response, and that extensive characteristics such as thickness can be more influential than the intensive properties of the materials. Optimization of electrode thicknesses to balance rate capability with abuse safety is discussed, and opportunities for multifunctional application as load-bearing structural components are considered. Improved battery safety characteristics are demonstrated by reorienting the inherent components of the cell, without altering the chemical make-up, emphasizing the profound influence of structural design.