A green route based on π-π interactions to coat graphite for high-rate and long-life anodes in lithium-ion batteries

Abstract

Although graphite (G) materials dominate the commercial lithium-ion battery (LIBs) anode market due to their excellent overall performance, their limited rate performance and cycle life hinder applications in high-performance fields. To improve the cycling and rate performance of graphite anodes, this study first employed economical and eco-friendly tannic acid (TA) as a carbon coating precursor to coat graphite surfaces via π-π stacking interactions. In an oxygen-rich alkaline environment, tannic acid undergoes oxidation polymerization and crosslinks with formaldehyde to form a polymer matrix that coats the graphite surface. After subsequent carbonization, carbon-coated graphite material (G@C) was successfully synthesized. Carbon coatings on graphite effectively lower LIB resistance, enhance lithium-ion diffusion, and prevent exfoliation during cycling, thereby significantly boosting rate performance and prolonging the cycle life of graphite. After 500 cycles at 2C, the specific capacity of G@C was 103.7 mAh g⁻¹, with a retention of 89%. However, G exhibited only 68.7 mAh g⁻¹ and 85% retention under identical conditions. This carbon-coated graphite modification strategy offers a novel, green, and economical approach for designing and tailoring graphite anode materials for lithium-ion batteries with long cycle life and high rate.