Synergistic Design of a SiO ₂ –CNT–Amorphous Carbon 3D Host for Stable SEI Formation and Long‐Term Cycling Stability of Lithium Metal Anodes

Lithium metal batteries (LMBs) offer exceptionally high energy density but suffer from dendritic lithium growth and large volume changes. Employing three‐dimensional (3D) host electrodes is a promising strategy to mitigate these challenges. Here, a 3D composite host comprising conductive carbon nanotubes (CNTs) and amorphous carbon with uniformly distributed SiO 2 (SiO 2 @AC‐CNT) is fabricated through spray pyrolysis followed by carbonization. The synergistic integration of SiO 2 , CNTs, and amorphous carbon optimizes electrical conductivity and lithiophilicity, enabling uniform, dendrite‐free lithium deposition, while the amorphous carbon domains promote a Li 2 CO 3 ‐rich solid electrolyte interphase that facilitates lithium‐ion transport and suppresses parasitic reactions. In asymmetric cell tests, the SiO 2 @AC‐CNT electrode delivers an average coulombic efficiency of 99.5% for 100 cycles at 2.0 mA cm −2 . With a lithium loading of 3.0 mAh cm −2 , symmetric cell tests of the SiO 2 @AC‐CNT sustain more than 1300 h at 1.0 mA cm −2 with stable voltage hysteresis and a low overpotential of 18 mV. Paired with a commercial LiFePO 4 cathode, the full cell exhibits excellent capacity retention over 600 cycles at 2.0 C, highlighting its potential as a stable and high‐performance 3D host for practical LMB.