Full-molar-ratio synthesis and enhanced lithium storage properties of CoxFe1−xCO3 composites with an integrated lattice structure and an atomic-scale synergistic effect

Abstract

Multicomponent composites with an integrated lattice structure can possess an atomic-scale distribution of different components within the crystallites and may express an enhanced synergistic effect compared to the mechanical mixture. In this paper, a series of cobaltous-ferrous carbonates Co_xFe_1−xCO₃ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) have been synthesized via a facile hydrothermal route with the assistance of ascorbic acid (AA). The four multicomponent Co_xFe_1−xCO₃ composites exhibit hexagonal structures similar to those of the monocomponents FeCO₃ and CoCO₃, and the resulting rodlike crystallites give aspect ratios and unit-cell parameters linearly changed along with the increasing x value, indicating the successful synthesis of Co_xFe_1−xCO₃ composites at an arbitrary Co/Fe molar ratio. When used as lithium ion battery anodes, the Co_xFe_1−xCO₃ composites can well inherit both the high-conductivity characteristic of CoCO₃ and the low-rate cycling stability of FeCO₃. In particular, each composite presents better electrochemical properties than the corresponding xCoCO₃ + (1 − x)FeCO₃ mixture, mainly assigned to an inner atomic-scale synergistic effect within the formula Co_xFe_1−xCO₃. Therefore, Co_xFe_1−xCO₃ composites may serve as novel high-capacity LIB anode materials for practical application, and also a facile strategic approach is introduced for the full-molar-ratio synthesis of multicomponent composites.