Nano/Microstructured\nSilicon–Graphite Composite\nAnode for High-Energy-Density Li-Ion Battery

Abstract

With\nthe ever-increasing demand for lithium-ion batteries (LIBs)\nwith higher energy density, tremendous attention has been paid to\ndesign various silicon-active materials as alternative electrodes\ndue to their high theoretical capacity (ca. 3579 mAh g^–1). However, totally replacing the commercially utilized graphite\nwith silicon is still insurmountable owing to bottlenecks such as\nlow electrode loading and insufficient areal capacity. Thus, in this\nstudy, we turn back to enhanced graphite electrode through the cooperation\nof modified silicon via a facile and scalable blending process. The\nmodified nano/microstructured silicon with boron doping and carbon\nnanotube wedging (B–Si/CNT) can provide improved stability\n(88.2% retention after 200 cycles at 2000 mA g^–1) and high reversible capacity (∼2426 mAh g^–1), whereas the graphite can act as a tough framework for high loading.\nOwing to the synergistic effect, the resultant B–Si/CNT–graphite\ncomposite (B–Si/CNT@G) shows a high areal capacity of 5.2 mAh\ncm^–2 and excellent cycle retention of 83.4% over\n100 cycles, even with ultrahigh active mass loading of 11.2 mg cm^–2,which could significantly surpass the commercially\nused graphite electrode. Notably, the composite also exhibits impressive\napplication in Li-ion full battery using 2 mol % Al-doped full-concentration-gradient\nLi­[Ni_0.76Co_0.09Mn_0.15]­O₂ (Al2-FCG76) as the cathode with excellent capacity retention of\n82.5% even after 300 cycles and an outstanding energy density (8.0\nmWh cm^–2) based on the large mass loading of the\ncathode (12.0 mg cm^–2).