Experimental study of multifunctional NCM-Si batteries with self-actuation

Among anode materials for lithium ion batteries, silicon (Si) in known for high theoretical capacity and low cost. Si exhibits over 300% volume change during cycling, potentially providing large displacement. In this paper, we present the design, fabrication and testing of a multifunctional NCM-Si battery that not only stores energy, but also utilizes the volume change of Si for actuation. The battery is transparent, thus allowing the visualization of the actuation process during cycling. This paper shows Si anode design that stores energy and actuates through volume change associated with lithium insertion. Experimental results from a transparent battery show that a Cu current collector single-side coated with Si nanoparticles can store 10.634 mWh (charge)/ 2.074 mWh (discharge) energy and bend laterally with over 40% beam length displacement. The unloaded anode is found to remain circular shape during cycling. Using a unimorph cantilever model, the Si coating layer actuation strain is estimated to be 30% at 100% SOC.