As lithium-ion batteries (LIBs) find application in new fields, the specific capacity of single LIBs must be enhanced, and the backward-cell problem in battery modules must be solved. Here, Mn3O4 and carbon nanofragment (Mn3O4/CNF) composites are synthesized and shown to have higher capacities than commercial graphite (theoretical capacity of approximately 372mAh·g−1) and hierarchical voltage plateaus. Nanosized Mn3O4 particles are introduced into the CNFs to simultaneously increase the specific capacity and prevent the corresponding LIB modules from over-discharging. The Mn2+-modified CNFs are spray-dried and calcined to form Mn3O4/CNF composites with 1.62%, 3.21%, and 6.74% Mn, which exhibit enhanced reversible specific capacities of 486.1, 609.3, and 539.0mAh·g−1, respectively, at 0.1C after 100 cycles. Furthermore, the additional voltage plateau at 1.2V due to Mn3O4 can help prevent the corresponding LIB modules from over-discharging and metallic lithium deposition on the anode.