A multifunctional boron-doping graphene/lithium carbonate (BG/LCO) nanointerfacial interphase is designed on the surface of commercial LiFePO4 particles using a CO2 reduction method. This innovation first leverages the self-catalytic properties of the BG/LCO layer to create a robust inorganic LiF-rich CEI while simultaneously enhancing electron and Li+ conductivity and strengthening FeO bonding.
Abstract
Lithium iron phosphate (LFP) cathode is renowned for high thermal stability and safety, making them a popular choice for lithium-ion batteries. Nevertheless, on one hand, the fast charge/discharge capability is fundamentally constrained by low electrical conductivity and anisotropic nature of sluggish lithium ion (Li+) diffusion. On the other hand, the interface and internal structural degradation occurs when subjected to high-rate condition. Herein, a multifunctional boron-doping graphene/lithium carbonate (BG/LCO) nanointerfacial layer on surface of commercial LiFePO4 particles is designed, in which the BG layer catalyzes the rapid reaction of Li2CO3-LiPF6 for homogeneous and mechanically robust inorganic LiF-rich structure across the cathode-electrolyte interphase (CEI), forms a conductive network to significantly enhance both electron and Li+ transport, and strengthens the FeO bonding to minimize both Fe loss and the formation of Fe-Li antisite defects. Correspondingly, the modified LFP cathode achieves a high capability of 113.2 mAh g−1 at 10 C and extraordinary cyclic stability with 88.0% capacity retention over 1000 cycles as compared to the pristine LFP cathode with a capacity of only 94.0 mAh g−1 and 64.6% capacity retention. It also exhibits great enhancements of 20.1% and 3.7% at higher-rate condition (room temperature/15 C) and the low temperature condition (−10 °C/1 C), respectively.