Silicon-Based Graphite Electrode Materials–Impact of Electrode Architecture on Electrochemical Performance and Cell Degradation

Graphite is commonly used as anode material in commercial lithium-ion-batteries (LIBs). Due to the demand for a significantly increased energy density for electrical vehicles, there is worldwide a strong effort in research and development to add silicon nano-particles to composite electrodes. Pure silicon has the benefit to enable almost one order of magnitude higher gravimetrical energy densities than graphite. Due to a huge volume expansion of silicon of about 300 % during electrochemical cycling it is so far most promising for commercialization to use silicon/graphite composites, instead of pure silicon. However, for silicon/graphite electrodes, the volume expansion during lithiation is still a problem regarding an enhanced cell degradation. Thick film electrodes are further concept to enable increased energy densities on cell level by avoiding inactive cell components namely separator and current collector materials. Due to limitations in diffusion kinetics in thick film electrodes and an increased diffusion overpotential at high charging/discharging currents, a significant drop in power density is observed. Material processing using ultrafast laser radiation provides now an exceptional approach to overcome power and lifetime limitations of thick-film and silicon/graphite electrodes. ... mehrLaser structuring was applied on electrode materials without changing the electrochemical and material properties of the active material by maintaining mechanical integrity. Post-mortem studies using laser-induced breakdown spectroscopy were carried out. A reduced cell degradation was achieved with structured electrodes in comparison to unstructured ones. Laser structuring of electrodes offers a new manufacturing tool for next-generation battery production to overcome current limitations in electrode design and cell performance.