Graphene as conductive additives for enhancing the electrochemical performance of commercial cathode materials (e.g., LiFePO₄, LiCoO₂, and LiMn₂O₄) in advanced Li-ion batteries (LIBs) has attracted great attention in recent years. However, the LiFePO₄ and LiCoO₂ electrodes usually show a poor rate capability when using graphene as the conductive additive, since its planar structure hinders ion transmission. Herein, a variety of reduced graphene oxides (rGO-x) have been successfully prepared using the modified Hummer's method followed by calcination. The results show that due to a large specific area and moderate defect density, rGO-5 can ensure good enough interfacial contact between active material particles and collector, thus maintaining fast electron/ion transportation. It has been found that LiFePO₄ and LiCoO₂ electrodes exhibit good lithium storage properties of 160.95 and 139.41 mA h g^-1 at a rate of 0.1 C when rGO-5 is utilized as a conductivity additive. Meanwhile, combined with the electrochemical impedance and kinetic exploration, it can be seen that the LiFePO₄ and LiCoO₂ electrodes demonstrate a high Li⁺ diffusion coefficient (D_Li+) of 6.7 × 10^-14 cm² s^-1 and 4.3 × 10^-13 cm² s^-1, respectively. Therefore, this research sheds new light on the practical utilization of rGO additives in high-performance lithium-ion batteries.

中文翻译：

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具有一定缺陷浓度的还原氧化石墨烯导电添加剂使锂离子电池的倍率能力成为可能


近年来，石墨烯作为用于增强先进锂离子电池 （LIB） 中商用正极材料（如 LiFePO₄、LiCoO₂ 和 LiMn₂O₄）电化学性能的导电添加剂引起了广泛关注。然而，当使用石墨烯作为导电添加剂时，LiFePO₄ 和 LiCoO₂ 电极通常表现出较差的倍率能力，因为其平面结构阻碍了离子传输。在此，使用改进的 Humer's 方法和煅烧成功制备了多种还原石墨烯氧化物 （rGO-x）。结果表明，由于比面积大、缺陷密度适中，rGO-5 可以保证活性材料颗粒与捕收剂之间足够好的界面接触，从而保持快速的电子/离子传输。研究发现，当 rGO-5 用作电导率添加剂时，LiFePO₄ 和 LiCoO₂ 电极在 0.1 C 的速率下表现出 160.95 和 139.41 mA h ^g-1 的良好储锂性能。同时，结合电化学阻抗和动力学探索，可以看出 LiFePO₄ 和 LiCoO₂ 电极表现出较高的 Li⁺ 扩散系数 （D_Li+），× ^10-14 cm^{2 s-1} 和 4.3 × 10-13 cm^{2 s-1}分别。因此，本研究为 rGO 添加剂在高性能锂离子电池中的实际应用提供了新的思路。