Improving rate performance of FeC2O4/rGO composites on lithium storage via single-polymerization‐induced electrostatic self‐assembly

Based on the wide interlayer distance for ions diffusion, iron (II) oxalate exhibits excellent lithium storage ability. However, the local deposition of metallic nanoparticles of Fe0 leads to low electrochemical reactivity, which hinders the actual application of FeC2O4 in large current regions (>5C). To solve this problem, a strong cationic polymeric electrolyte, polyelectrolyte diallyl dimethyl ammonium (PDDA), was introduced to construct a [FeC2O4(PDDA)]+ ligand. By single-polymerization‐induced electrostatic self-assembly, the [FeC2O4(PDDA)]+ ligand was combined with the surface-charged rGO to produce a FeC2O4/rGO material. It is proved that the rGO carrier improves the interparticle conductivity, electrochemical activity and structure stability of the iron (II) oxalate particles, ensuring the stability of Li || FeC2O4/rGO battery at a rapid charging rate of 20C (8 A g−1) for more than 500 cycles (with the special capacity of 713 mAh g−1). Compared with FeC2O4 electrode, owning to high reactivity of rGO and continuously activating on the nanoscale Fe metal generated at ∼0.75 V, FeC2O4/rGO shows higher electrochemical activity of conversion reaction in the first 50 cycles and better reversibility in the rate charge–discharge test (the capacity rapidly increased to 1158.8 mAh g−1 after 20C cycles). This work reveals how the structural design of conducting and supporting the carrier can achieve fast charging for iron (II) oxalate lithium-ion batteries.