On-chip high power porous silicon lithium ion batteries with stable capacity over 10000 cycles

We demonstrate the operation of a graphene-passivated on-chip porous silicon material as a high rate lithium battery anode with over 50X power density, and 100X energy density improvement compared to identically prepared on-chip supercapacitors. We demonstrate this Faradaic storage behavior to occur at fast charging rates (1-10 mA cm^-2) where lithium locally intercalates into the nanoporous silicon, preventing the degradation and poor cycling performance attributed to deep storage in the bulk silicon. This device exhibits cycling performance that exceeds 10000 cycles with capacity above 0.1 mA h cm^-2 without notable capacity fade. This demonstrates a practical route toward high power, high energy, and long lifetime all-silicon on-chip storage systems relevant toward integration into electronics, photovoltaics, and other silicon-based platforms.