Design of porous Si/C–graphite electrodes with long cycle stability and controlled swelling†
Silicon (Si) is one of the most promising candidates to replace graphite anodes in the next generation of Li ion batteries. Although various approaches have been adopted to improve the performance of Si-based anodes over the last few years, a main challenge in the practical application of Si-based anodes, i.e., the thickness swelling of a Si based anode, has been much less investigated. Here, we use a porous Si/C–graphite electrode as an example to elucidate the design principle for stable Si anodes of controlled thickness swelling. Excellent agreement between the theoretical design and experimental data was demonstrated. The practical electrode (∼3 mA h cm−2 loading) with a specific capacity of ∼650 mA h g−1 has ∼82% capacity retention over 450 cycles. The initial electrode swelling upon full lithiation is <20%. The calendered electrodes demonstrated ∼56% end-of-life swelling and ∼90% capacity retention after 200 cycles. The full-cell of Li(Ni1/3Mn1/3Co1/3)O2 and the pre-lithiated anode demonstrates >84% capacity retention over 300 cycles.