Portable electronic devices rely on portable power sources. Li batteries have been the centerpiece of cellular phones, notebook computers, camcorders, digital cameras, etc. Li is positioned right below hydrogen in the Periodic Table, so batteries built upon other materials cannot surpass the capacity of Li batteries.
Graphite is now widely used as the anode material in Li ion batteries. However, the theoretical capacity of graphite having LiC6 composition is only 372 mAhr/g, which can be reached within 0-300 mV versus metallic Li[1, 2]. Therefore, research to change the graphite to a high performance material is essential to develop the next-generation, highperformance Li ion battery.
The anode material for the next generation Li ion battery should be one that can be alloyed with Li. Sn, Al and Si have much higher theoretical capacities than graphite, with Si in the Li4.4Si formation having the highest theoretical capacity, 4200 mAhr/g. However, immense volume changes happen in the Li alloy anode. In case of Si, as Li insertion and extraction continues, the performance fades rapidly because of volume change of about 310% taking place during charging and discharging.
In this report, we have investigated the morphological change of the Si electrodes during repeated charging and discharging, and tested novel ideas to circumvent or avoid the capacity decrease with the cycle number.