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. - Highlights: • A yolk-shell structure is proposed for anodes of lithium-ion batteries. • Cr₂O₃@carbon@graphene is fabricated via a spray drying route. • The multi-protection makes sure the excellent properties to store lithium-ions.