Micron-sized Secondary Silicon Spherical Composite for Practical Li-ion Batteries

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)


The ever-growing demand for smaller batteries with higher energy density and longer life cycle has triggered research interest on metal alloy materials as an anode for Li-ion batteries (LIBs) in broad applications such as electric vehicle and portable electronics, because metal alloys usually possess much higher theoretical gravimetric and volumetric capacities than those of graphite. Si has been considered as potential candidate due to its highest capacity (4200 mAh/g, according to a state of Li4.4Si), low price and high abundancy. However, progressively large volume change during the charge and discharge reactions hinders Si from being commercially used. We have successfully developed a micron-szied secondary Si-based composite (MSC), with Si nanoparticles (diameter ~70 nm, commercial) embedded in a porous conductive network constructed with conductive carbon and binder materials. Si NPs were purchased in bulk and used as received. The MSC anode exhibited an initial CE of 81%, and >99.8% thereafter. The volume expansion of Si has been effectively limited inside the secondary particle, avoiding damage to the structure of electrode. As a result, the MSC electrode delivered excellent cycling stability with 8% loss over 500 cycles at a rate of 0.5C. Considering the advantages of micron-sized composite, this material could be of interest in the application of real-life LIBs.