Preparation and performance studies of low-cost graphite thick dry electrodes

doi:10.19799/j.cnki.2095-4239.2024.1234

Abstract

Abstract:

A graphite dry electrode for lithium-ion batteries was fabricated using a binder fiberization technique. The effects of electrode thickness, polytetrafluoroethylene (PTFE) content, and carbon nanotube (CNT) addition on electrode performance were systematically investigated. Morphological and elemental distribution analyses were conducted using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Mechanical, electrical, and wetting properties were evaluated using a universal testing machine, a four-probe internal resistance meter, and an optical contact angle goniometer, respectively. Electrochemical performance was assessed through charge-discharge testing. The results showed that when the electrode thickness exceeded 300 μm, electrochemical performance deteriorated markedly; therefore, the thickness should be limited to ≤300 μm. Based on comprehensive evaluation, including electrochemical behavior, tensile strength, conductivity, and electrolyte wettability, the optimal formulation was identified as graphite∶PTFE∶CNT∶Super P (SP) at a mass ratio of 96∶1∶1∶2. This composition yielded a coulombic efficiency of 91.7%, a reversible capacity exceeding 330 mAh/g, a surface capacity of 11.28 mAh/cm², a tensile elongation of 9.06%, a resistance of 24.1 Ω, and a contact angle of 65.33°. SEM images confirmed the presence of abundant PTFE fibers on the surface and cross-section of the electrode, forming a branched and hierarchically structured network throughout the electrode matrix. The inclusion of CNTs enhanced both the resilience and conductivity of the electrode sheet, facilitating easier fabrication. To meet the growing demand for high energy density, thick electrode manufacturing has become a critical focus. Unlike conventional wet-coating techniques, dry electrode fabrication eliminates the need for solvents, offering a cost-effective, environmentally friendly, and scalable approach to producing thick electrodes.

Key words: lithium-ion batteries, dry electrode, PTFE fiberization, graphite, thick electrode

CLC Number:

TB 332

Jingjing RUAN, Xiangkun WU, Yonghui LI, Chongchong ZHAO, Shenshen LI, Tongfei WANG, Shengjie LIANG, Guihong GAO. Preparation and performance studies of low-cost graphite thick dry electrodes[J]. Energy Storage Science and Technology, 2025, 14(6): 2248-2255.

Figures/Tables 9

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References 12

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石墨∶PTFE∶CNT∶SP	放电比容量/(mAh/g)	充电比容量/(mAh/g)	首效/%	10圈后容量保持率/%	厚度/μm	面密度/(mg/cm²)
94∶3∶0∶3	397	314	79	93.3	242	33
95∶2∶0∶3	401	331	82.5	92.7	243	34.9
96∶1∶0∶3	376	316	84.1	95.5	245	33.8
95∶2∶1∶2	359	306	85.3	83.5	235	34.5
96∶1∶1∶2	362	332	91.7	94.5	230	35.5
97∶1∶1∶1	348	304	87.3	93.3	232	32.3
97∶1∶0.7∶1.3	354	312	88.2	90.8	230	31.4
97.5∶0.5∶0.7∶1.3	335	290	86.6	91.5	251	35.1
98∶0.5∶0.7∶0.8	356	304	85.3	89.9	261	34.5

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