Silicon-based anodes for lithium-ion batteries: Effectiveness of materials synthesis and electrode preparation

Lithium-ion batteries are widely used throughout the world for portable electronic devices and mobile phones and show great potential for more demanding applications like electric vehicles. Unfortunately, lithium-ion batteries still lack the required level of energy storage to completely meet the demands of such applications as electric vehicles. Among advanced materials being studied, silicon nanoparticles have demonstrated great potential as an anode material to replace the commonly used graphite. Silicon has been shown to have a high theoretical gravimetric capacity, approximately 4200 mA h/g, compared to only 372 mA h/g for graphite. Though silicon nanoparticles have remarkably high capacity, they suffer from rapid degradation with each cycle due to electrode volume expansion of approximately 400% during lithiation, placing a large strain on the material. With each cycle that strain creates cracks in the electrode particles and causes them to break down into smaller particles, which create void spaces between the particles and lead to poor contact as reflected in poor conductivity. In this review, we discuss exciting new research on silicon-based anodes conducted during the past couple of years. Besides stressing the importance of well-designed nanostructures of Si, we focus on optimization of the Si electrode and resulting performance enhancement by properly selecting binders and synergistically integrating them with various carbon materials during electrode design and fabrication. Importantly, although each improvement strategy has its own advantage, appropriate combination of them will yield much higher anode performance. We summarize the core issues in developing the silicon anode and effective strategies in yielding more promising results.