A Composite Coating Derived from Aluminum Lactate Promoting the Electrochemical Performance of Natural Graphite

Natural graphite (NG) is the ideal anode material for Li-ion batteries due to its high cost performance. The main issue hindering the wide application lies in the unstable solid electrolyte interphase (SEI) that leads to unsatisfactory cyclability and rate performance. In this work, a multifunctional coating layer was constructed on the NG surface through hydrothermal treatment with aluminum lactate (AL) and subsequently sintered at 500 °C. The strong coordination of Al3+ allows some residual carboxylates to remain in the coating, thus achieving the composite coating comprised of carbon, amorphous Al2O3, and carboxylates after the sintering, conducive to reducing charge-transfer resistance, improving Li+ diffusion, and boosting the interaction between the NG particles and binder. Therefore, the AL-modified NG demonstrates outstanding rate performance (attaining average specific delithiation/lithiation capacities of 333.0/334.6 mAh g–1 at 0.5 C) and cyclability. The simple energy-efficient modification strategy with the inexpensive precursor of AL could be practically used to produce the NG anode material with outstanding performance.