High-Strength Silicon Anodes with High Tap Density via Compression Carbonization for Liquid and All-Solid-State Lithium-Ion Batteries

Despite the advantages of nanostructure design with a balance of capacity and cycle life, the low tap density (<1 g cm^-3) and high swelling properties make nanostructured silicon far from practical in applications. Here, we design a free-standing silicon graphite composite integrated anode through facile one-pot sintering with pitch under pressure. The thermomechanical effect during compression carbonization enables the integrated electrode to achieve a high tap density of 1.51 g cm^-3, >2 times that of typical free-standing electrodes. In situ expansion measurements demonstrate that the longitudinal expansion of integrated electrodes is <20% of that of conventional electrodes. A rational conductive framework enables integrated electrodes to exhibit remarkable cycling stability in both liquid lithium-ion batteries (77.6% capacity retention after 500 cycles) and all-solid-state lithium-ion batteries (98.5% capacity retention after 1000 cycles). In particular, integrated electrodes remain stable even with a high areal capacity of 12.6 mAh cm^-2.