AbstractA strategy to synthesize a Fe3O4@carbon nanotube (CNT) composite with high tap density of 1.22 g cm−3 and electronic conductivity of 4.1 S cm−1 is developed. The Fe3O4@CNT composite exhibits an extremely high capacity of over 1263 mAh g−1, even after 125 cycles at a current density of 100 mA g−1. Additionally, a lithium‐ion full battery of Fe3O4@CNT|LiNi0.5Mn1.5O4 with an energy density of 2283 Wh kganode−1 (381 Wh kgcathode−1) is successfully configured. After optimization of the work voltage windows and electrolyte additives, it has a capacity retention of 71 % after more than 400 cycles. Using this synthetic strategy, additional metal oxide@CNT (e.g., Co3O4, MnO2, CuO, ZnO) composites with high lithium storage capability are explored, and their electrochemical differences versus the cathode of LiNi0.5Mn1.5O4 are investigated in light of their superior performances. Applying this type of metal oxide‐based composite in full cells is a significant step to the development of high‐energy lithium‐ion batteries and to further applications in current sodium‐ion batteries.