Design and synthesis of Cr2O3@C@G composites with yolk-shell structure for Li+ storage

Cr2O3 is of high theoretical capacity for lithium-ion (Li+) storage. However, its cyclic stability is very poor due to the large volume change during lithiation/delithiation. In addition, the low conductivity of Cr2O3 blocked the fast transfer of electrons, resulting in an inferior rate capacity. In this study, we design yolk-shell Cr2O3 composites using carbon/Cr2O3 as core and graphene as shell to improve the conductivity of electrode materials and provide spaces for the volume change of Cr2O3. Therefore, this composites (Cr2O3@C@G) exhibit a higher specific capacity and stable cyclic performance achieved the remarkable reversible capacity of 648 mA hg(-1) after 120 cycles at 0.1 A g(-1), even a capacity of 347 mA hg(-1) is obtained after 600 cycles at 1 A g(-1). Due to the space between carbon sphere and graphene, they not only effectively alleviate the volume expansion of Cr2O3, but also enhance the electrochemical properties of the composites. Eventually the electronic conductivity and Li+ diffusion rate more pleasantly during cycling due to the excellent structural characteristics. (C) 2017 Elsevier B.V. All rights reserved.