 To boost the electrochemical performance of MnCO3 (MC) microspheres, binary SbxMn1−xCO3 (x = 1/3, 1/2 and 2/3) microspheres, labeled SMC-12, SMC-11 and SMC-21, respectively, were prepared using a solvothermal method. A 3D conductive network of carbon nanotubes (CNT) was also successfully built from the inside to the surface of the SMC-12 microspheres to promote electronic and ionic transportation. As observed, the microspheres of SMC-12 were larger and had a more uniform distribution compared with pure MC, SMC-11 and SMC-21. Profiting from the introduction of neural-like CNTs networks, the electrochemical performance and the utility of the SMC-12 microspheres (approximately 3.5–7 µm in diameter) were remarkably improved. The obtained CNTs@SMC-12 composite anode delivered 1066 and 572 mAh g−1 at current densities of 500 and 5000 mAg−1 after 200 cycles, respectively, which were much higher than the 737 and 297 mAh g−1 of bare SMC-12.