Three-dimensional graphene-wrapped Co0.85Se@C as high volumetric capacity anode material for lithium-ion batteries.

Three-dimensional graphene-wrapped Co 0.85 Se@C hybrids with high volumetric capacities are prepared as anode materials for lithium-ion batteries. • A novel three-dimensional graphene-wrapped Co 0.85 Se@C composite is synthesized. • C-O-Co is formed from reactions between the Co 0.85 Se@C and oxygen-containing groups. • The specific capacity of GCS reaches to 1022.5 mAh g−1 after 200 cycles at 0.1 A g−1. • The anode electrode exhibits good long-cycling durability and rate performance. To overcome the drawbacks of poor long-term cyclic and large volume expansion for selenides, which have high theoretical specific capacity and are promising candidates to fulfill the requirement of high volumetric energy density for lithium-ion batteries, we prepared a novel three-dimensional graphene-wrapped Co 0.85 Se@C composite (3D-G@Co 0.85 Se@C) through a capillary evaporation-induced drying method. This process leads to a shrinkage of graphene assembly, generating an ideal configuration compact composite material. XPS analysis confirms that the C-O-Co is formed from reactions between the Co 0.85 Se@C and oxygen-containing groups on graphene oxide during the preparation process. Such a strong covalent interaction between the Co 0.85 Se@C and graphene, together with its compact structure are favorable to high volumetric capacity. The electrochemical measurements show that the specific capacity of the GCS is about 1022.5 mAh g−1 after 200 cycles at 0.1 A g−1, corresponding to a remarkably reversible volumetric capacity of 2096.1 mAh cm−3. Moreover, good long-cycling durability and rate performance are also achieved. Consequently, this composite is a promising electrode material with high volumetric capacity in lithium-ion batteries. [ABSTRACT FROM AUTHOR]