Hydrothermal modification of natural graphite with KCl: different roles of K+ and Cl− in promoting the electrochemical performance of Li-ion batteries

IF 2.4 4区化学 Q3 CHEMISTRY, PHYSICAL

Ionics Pub Date : 2024-07-23 DOI:10.1007/s11581-024-05718-8

Zong‒Xiao Zhao, Wei Liu, Yong‒Xin Qi, Yu‒Jun Bai

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Abstract

The poor structural stability and cyclability restrict the wide application of natural graphite (NG) in Li-ion batteries (LIBs). Herein, NG was hydrothermally modified with KCl at 200 °C for 12 h. The NG modified with 1.0 wt% KCl exhibits excellent rate performance (revealing average lithiation capacities of 407.7 mAh g⁻¹ at 0.1 C and 341.2 mAh g⁻¹ at 0.5 C) and cyclability. The roles of K⁺ and Cl⁻ in promoting the electrochemical performance of NG was revealed via systematic characterizations. In the hydrothermal process, K⁺ entered into graphene interlayers to enhance electronic conductivity and introduce lattice distortion in NG to facilitate Li-ion transport during lithiation and delithiation, while Cl⁻ interacted with the NG surface to create C‒Cl bonds which are partially converted into Li-conductive LiCl during lithiation to function as the component of solid electrolyte interphase. Both the residual C‒Cl bonds and in situ formed LiCl with high stability could stabilize the structure and performance of the NG anode. This simple hydrothermal modification with KCl might promote the wide utilization of the NG anode in LIBs.

Graphical Abstract

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用 KCl 对天然石墨进行水热改性：K+ 和 Cl- 在促进锂离子电池电化学性能方面的不同作用

天然石墨（NG）的结构稳定性和循环性较差，限制了其在锂离子电池（LIB）中的广泛应用。用 1.0 wt% KCl 修饰的天然石墨具有优异的速率性能（0.1 C 时的平均锂化容量为 407.7 mAh g-1，0.5 C 时的平均锂化容量为 341.2 mAh g-1）和可循环性。通过系统表征揭示了 K+ 和 Cl- 在促进 NG 电化学性能方面的作用。在水热过程中，K+进入石墨烯夹层，增强了电子传导性，并在 NG 中引入了晶格畸变，以促进锂离子在锂化和脱锂过程中的传输；而 Cl- 与 NG 表面相互作用，生成了 C-Cl 键，并在锂化过程中部分转化为锂导电的氯化锂，成为固体电解质间相的组成部分。残留的 C-Cl 键和原位形成的高稳定性氯化锂都能稳定 NG 阳极的结构和性能。这种用氯化钾进行的简单水热改性可能会促进氮气阳极在锂离子电池中的广泛应用。

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来源期刊

Ionics 化学-电化学

CiteScore

5.30

自引率

7.10%

发文量

427

审稿时长

2.2 months

期刊介绍： Ionics is publishing original results in the fields of science and technology of ionic motion. This includes theoretical, experimental and practical work on electrolytes, electrode, ionic/electronic interfaces, ionic transport aspects of corrosion, galvanic cells, e.g. for thermodynamic and kinetic studies, batteries, fuel cells, sensors and electrochromics. Fast solid ionic conductors are presently providing new opportunities in view of several advantages, in addition to conventional liquid electrolytes.