FeCO3 (FCO), FeCO3/rGO (FCOG) and Fe0.8Mn0.2CO3/rGO (MFCOG) nanocomposites are synthesized via a facile and controllable one-step hydrothermal process. XRD, SEM and TEM characterizations show that Mn ions can successfully substitute for partial iron atoms in FeCO3 nanocrystals without any crystal structure changes. Applied as anodes for lithium-ion batteries (LIBs), MFCOG delivers optimal electrochemical performance with a reversible capacity of 1223 mAh g(-1) at a current density of 0.2 A g(-1) after 120 cycles. Furthermore, MFCOG maintains a specific capacity of 613 mAh g(-1) at a high current density of 1.6 A g(-1), showing the enhanced rate capabilities and stable cycling performance. It indicates that the excellent lithium storage performance of MFCOG is mainly related to its well-designed nanostructure of doped metal carbonates and rGO nanosheets with high electrical conductivity which can work as effective conductive matrix and restrain the agglomeration of FeCO3, leading to synergistic effects on improving the structural integrity and accommodating the volume changes of MFCOG during the process of lithium intercalation/deintercalation. (C) 2017 Elsevier B.V. All rights reserved.