Critical Investigation of Metal–Organic-Frameworks to Improve the Silicon Anode of Lithium-Ion Batteries

The poor capacity retention of the silicon (Si) anode has hindered its widespread use in lithium-ion batteries. Metal–organic-frameworks (MOF) may offer the structural and functional tunability needed to alleviate some of the longstanding problems associated with silicon pulverization. Herein, MOF-74 (Co-based) and MOF-199 (Cu-based) were implemented in different design configurations for high-Si loading electrodes. Multilayer sandwich configurations provided a modest improvement in capacity retention. However, greatest improvements in capacity retention were observed when the MOF was in situ synthesized onto the silicon surface (Si@MOF) and subsequently pyrolyzed. The best performing high-loading 0.5Si@MOF-c sample delivered a high capacity of 1000 mAh/g and retained 60% capacity after 100 cycles, surpassing a standard silicon-graphite composite.