Sodium carboxymethylcellulose induced engineering a porous carbon and graphene immobilized magnetite composite for lithium-ion storage.

Immobilizing nanosized electrochemically active materials with supportive carbonaceous framework usually brings in improved lithium-ion storage performance. In this work, magnetite nanoparticles (FeO) are stabilized by both porous carbon domains (PC) and reduced graphene oxide sheets (RGO) to form a hierarchical composite (FeO@PC/RGO) via a straightforward approach. The PC confined iron nanoparticle intermediate sample (Fe@PC) was first fabricated, where sodium carboxymethylcellulose (Na-CMC) was employed not only as a cross-linker to trap ferric ions for synthesizing a Fe-CMC precursor sample, but also as the carbon source for PC domains and iron source for Fe nanoparticles in a pyrolysis process. The final redox reaction between Fe@PC and few-layered graphene oxide (GO) sheets contributed to the formation of FeO nanoparticles with reduced size, avoiding any severe aggregation or excessive exposure. The FeO@PC/RGO sample delivered a specific capacity of 522.2 mAh·g under a current rate of 1000 mA·g for 650 cycles. The engineered Fe@PC and FeO@PC/RGO samples have good prospects for application in wider fields.