In situ LiFePO4 nano-particles grown on few-layer graphene flakes as high-power cathode nanohybrids for lithium-ion batteries

Abstract

We have realized a Lithium Iron Phosphate (LFP)-graphene nanohybrid obtained by a direct LFP crystal colloidal synthesis on few-layer graphene (FLG) flakes produced by the liquid phase exfoliation (LPE) of pristine graphite. This hybrid material has been tested as a cathode in Li-ion batteries, achieving fast charge/discharge responses to high specific currents. We demonstrate a specific capacity exceeding 110 mAh g−1 at 20 C, with no electrode damaging. Our LFP-FLG electrodes display a low charge transfer resistance, chemical stability and steady electrochemical behavior even under stressful conditions, such as impulsive charges at a high-rate (5 C) and long cycles at 1 C (> 700 cycles). The LFP colloidal synthesis combined with the FLG production by LPE allows for tuning both the LFP-platelets like and FLG flake morphologies in order to promote an optimal connection between the LFP and FLG flakes, ensuring fast charge transfers and consequently high-rate electrochemical performances. The method here proposed yields a scalable production path, which can be easily extended to silicate-, phosphate- and fluorophosphates-based cathode materials for the next generation of high-power lithium batteries.