Hierarchical holey reduced graphene oxide-carbon quantum dot hybrid conductive additive enabling high-rate and long-cycle LiFePO4 cathodes

Abstract

LiFePO4 has been widely commercialized due to its long cycle life, excellent safety performance, and high operating voltage. However, its low electronic conductivity (10^-9-10^-10 S cm^-1) and slow lithium-ion diffusion rate (~10^-14 cm² s^-1) lead to capacity decay, limiting its application in electric vehicles. Therefore, this study proposes a strategy for constructing a multi-level conductive network: utilizing holey reduced graphene oxide as a two-dimensional conductive framework combined with carbon quantum dots interfacial modification to enhance the electronic/ionic transport network within LiFePO₄. Within the LiFePO₄ system, this approach achieves a discharge specific capacity of 134 mAh g^-1 at a charge quantity of 1 C with a minimal addition of only 2 wt%. After 300 cycles, the capacity retention rate remains at 80%. This superior performance is primarily attributed to the synergistic effect provided by the composite structure of holey reduced graphene oxide (HRGO) and carbon quantum dots (CQDs). This demonstrates that the HRGO-CQDs composite conductive agent holds promise as a candidate for novel conductive materials and opens a new pathway for enhancing the performance of lithium iron phosphate batteries.