Boosting Li-storage properties of conversion-type anodes for lithium-ion batteries via steric effect of intercalation-type materials: A case of MnCO_3

摘要

The conversion-type anodes have been widely investigated in lithium-ion batteries (LIBs), due to their high theoretical specific capacity. However, their rate capability and cyclic stability were suffered from large volume expansion and pulverization. Herein, we report a method to improve the electrochemical performance of conversion-type anodes by using the steric effect of intercalation-type materials, as was done in conversion-type MnCO3. The role of the intercalation-type TiO2 nanocrystals in the structural evolution of composite anodes was verified. It was found that TiO2 nanocrystals could form a good electrical contact with as-pulverized MnCO3 anode, and maintain their structural stability. Furthermore, the electrochemical analysis shows that TiO2 nanocrystals can provide fast electron transfer channels for the composites matrix, which is conducive to improving the rate capability of MnCO3 anode. Moreover, TiO2 nanocrystals can effectively avoid the aggregation of metal Mn nanocrystals by their steric effect. As a result, the composite anode showed better electrochemical properties than its counterpart MnCO3 by delivering 378 mA h g(-1) at a current density of 1 A g(-1) after 200 cycles. Different from previously reported methods, our strategy is simple and easy to scale. Importantly, our research provides a new insight for solving issues involved volume expansion and pulverization of conversion-type anodes.