Conductive agent

Conductive agents are materials added to battery electrodes to improve electronic conductivity by forming conductive pathways between active material particles and the current collector, thereby reducing internal resistance and improving charge–discharge performance.

In lithium-ion batteries, conductive carbons such as carbon black, graphite, and carbon nanotubes (CNTs) are commonly used for this purpose. CNTs, particularly single-walled carbon nanotubes (SWCNTs), can establish conductive pathways at lower loadings than conventional carbon additives due to their high aspect ratio and intrinsic electrical conductivity.^[1] This can be especially important in thick or high-mass-loading electrodes, where long-range electron transport becomes more difficult. However, their effectiveness depends strongly on dispersion, since nanotube aggregation can lead to heterogeneous electron transport and reduced electrode performance.^[2][3]

The conductive agent carbon black is used for improving the conductivity of the electrodes and decreasing the resistance of interaction.[1]

Carbon black conductive agent

The conductive carbon black is characterized by small particle size, particularly large specific surface area, and particularly good electrical conductivity, and it can function as a liquid absorption and liquid retention in the battery.^[4]

The carbon black conductive agents: acetylene black, 350G, carbon fiber (VGCF), carbon nanotubes (CNTs), Ketjen black (Ketjenblack EC300J, Ketjenblack EC600JD, Carbon ECP, Carbon ECP600JD).^[5]

Acetylene Black (Polyacetylene): carbon black obtained by continuous pyrolysis of acetylene having a purity of 99% or more obtained by decomposing and purifying by-product gas during pyrolysis of calcium carbide method or naphtha (crude gasoline).^{[citation needed]}

Ketjen Black: High-efficiency superconducting carbon black for lithium batteries, branched, high purity, and excellent electrical conductivity.^{[citation needed]}

Graphite conductive agent: KS-6, KS-15, SFG-6, SFG-15, etc.^{[citation needed]}

CNTs: the incorporation of CNTs as a conductive additive at a lower weight loading than conventional carbons, like carbon black and graphite, presents a more effective strategy to establish an electrical percolation network.^[6]

Carbon nanotube conductive agents in lithium batteries

Dispersion of SWCNTs using cellulose-based binders

Recent studies have emphasized that the effectiveness of carbon nanotube (CNT) conductive agents in lithium-ion batteries depends strongly on their dispersion within the electrode matrix. In particular, single-walled carbon nanotubes (SWCNTs) tend to aggregate due to van der Waals interactions, which can hinder the formation of continuous electron-conduction networks.

In a 2025 study, cellulose elementary fibrils (CEFs) were introduced as a binder system to improve the dispersion of SWCNTs in high-mass-loading cathodes. The SWCNTs used in the study were commercially sourced (Tuball, average diameter ~1.5 nm), representing a commercially available SWCNT material used in battery research. The CEF binder enabled uniform dispersion of SWCNTs without additional dispersants, attributed to increased surface area and anionic charge density of the fibrils. Raman spectroscopy showed a shift in the G-band from 1573 to 1592 cm⁻¹, interpreted as evidence of SWCNT de-aggregation.

The improved dispersion resulted in enhanced electronic conductivity of the cathode (7.4 S cm⁻¹) compared to electrodes using conventional binders, as well as more homogeneous electron-conduction pathways across the electrode thickness. The system enabled stable operation at areal mass loadings up to 50 mg cm⁻² and a reported specific energy of 445.4 Wh kg⁻¹. These results highlight the importance of binder–nanotube interactions in determining the performance of CNT-based conductive networks in battery electrodes.^[7]

References

1. He, X. (2023). "Perspective on carbon nanotubes as conducting agent in lithium-ion batteries: the status and future challenges". Carbon Letters. doi:10.1007/s42823-022-00449-0.
2. Lee, G. (2025). "CNT distribution governs lithium-ion battery cathode performance: From slurry rheology to long-term degradation". Chemical Engineering Journal. 525 170617. doi:10.1016/j.cej.2025.170617.
3. Kim, J. (2025). "Debundling of SWCNTs Using a Non-Toxic, Low Carbon Footprint Approach". Polymers. doi:10.3390/polym17223007.
4. Kuroda, Shintaro; Tobori, Norio; Sakuraba, Mio; Sato, Yuichi (June 2003). "Charge–discharge properties of a cathode prepared with ketjen black as the electro-conductive additive in lithium ion batteries". Journal of Power Sources. 119–121: 924–928. Bibcode:2003JPS...119..924K. doi:10.1016/s0378-7753(03)00230-1.
5. Takamura, Tsutomu; Saito, Morihiro; Shimokawa, Atushi; Nakahara, Chieko; Sekine, Kyoichi; Maeno, Siji; Kibayashi, Naoki (September 2000). "Charge/discharge efficiency improvement by the incorporation of conductive carbons in the carbon anode of Li-ion batteries". Journal of Power Sources. 90 (1): 45–51. Bibcode:2000JPS....90...45T. doi:10.1016/s0378-7753(00)00446-8.
6. Landi, Brian J.; Ganter, Matthew J.; Cress, Cory D.; DiLeo, Roberta A.; Raffaelle, Ryne P. (2009). "Carbon nanotubes for lithium ion batteries". Energy & Environmental Science. 2 (6): 638. Bibcode:2009EnEnS...2..638L. doi:10.1039/b904116h.
7. Hong, Y.-K.; Kim, J.-H.; Kim, N.-Y. (2025). "Cellulose Elementary Fibrils as Deagglomerated Binder for High-Mass-Loading Lithium Battery Electrodes". Nano-Micro Letters. 17: 112. doi:10.1007/s40820-024-01642-8.