Improving Cycle Life of Silicon-Dominant Anodes Based on Microscale Silicon Particles under Partial Lithiation

Abstract

Using only parts of the maximum capacity of silicon microparticles in a lithium-ion battery (LIB) anode represents a promising material concept. The high capacity, better rate capability compared with graphite and accessibility on an industrial scale, as well as its attractive cost make microsilicon an ideal choice for the next generation anode material. However, currently the cycle life of LIBs using silicon particles in the anode is limited due to drastic volume change of Si during lithiation and delithiation. Continuous formation of a solid electrolyte interphase (SEI) and the associated lithium loss are the main failure mechanisms, while particle decoupling from the conductive network plays a role mainly during operation at low discharge voltages. The present study discusses approaches on the material- and cell-level to enhance cycle performance of partially lithiated silicon microparticle-based full cells by addressing the previously described failure mechanisms. Reducing the surface area of the silicon particles and coating their surface with carbon to improve the electronic contact, as well as prelithiation to compensate for lithium losses have proven to be the most promising approaches. The advantageous combination of these routes resulted in a significant increase in cycling stability exceeding 600 cycles with 80% capacity retention at an initial capacity of about 1000 mAh g−1 at anode level, compared to only about 250 cycles for the non-optimized full cell.