Multi-functional carbon integrated rGO-Fe3O4@C composites as porous building blocks to construct anode with high cell capacity and high areal capacity for lithium ion batteries

For lithium ion batteries (LIBs), a high cell capacity, which requires both a high capacity and a high loading mass of active materials, is crucial for practical application. However, how to fabricate efficient anodes with high cell capacity and high areal capacity remains a challenge. To solve this issue, we design a structure of porous building block composed of multi-functional carbon integrated rGO-Fe 3 O 4 @C composites. The carbon shell of Fe 3 O 4 @C derived from polydopamine (PDA) acts as an artificial solid electrolyte interface (SEI) film to avoid the excessive SEI formation, within which there are sufficient lithium ion diffusion pathways derived from the spaces between Fe 3 O 4 nanocrystals. The carbon derived from the in-situ polymerized polyacrylamide and rGO act as a glue to integrate the as-obtained Fe 3 O 4 @C composites to form the porous building blocks. Due to the compact stacking of building blocks, the composite electrode achieves a high active material loading mass of 5.94   mg (5.25   mg   cm −2 ), while maintains a satisfying capacity (685   mAh   g −1 after the 100th cycle at 0.5   A   g −1 ) and good rate performance (440   mAh   g −1 at 3   C). Therefore, a high cell capacity (4.02   mAh) and a high areal capacity (3.6   mAh   cm −2 ) at 2.62   mA   cm −2 in a single CR2032 coin cell are achieved.