•Cost/energy-efficient scalable roll-to-roll system without toxic solvent involved•Deep analysis of the unique microstructure of the solvent-free electrodes•Significant lower tortuosity to enable fast-charging performance•Stable cycle life with uniform coating layer on the active material surface With the rapidly increasing demand for energy storage, the lithium-ion battery market keeps expanding. However, the conventional battery electrode manufacturing method involves toxic organic solvent and energy-consuming drying/recovering processes. The evaporation of the solvent leads to uneven materials distribution and the electrodes’ microstructure could impede the fast-charging ability. Here, we have developed a dry-printing method to avoid the toxic solvent in the conventional slurry cast method and skip the energy- and time-consuming drying process. The total manufacturing cost could be reduced by up to 15%, and the roll-to-roll system has huge potential to be scaled up. The properties and the mechanism of the dry electrodes have been deeply studied. The unique microstructure could also benefit the electrode with better fast-charging ability and longer cycle life. Thus, we believe this work paves a more efficient way for battery manufacturing with higher-quality electrode products. In response to the growing demand for lithium-ion batteries (LIBs), we demonstrate a solvent-free manufacturing technology that can avoid toxic organic solvents and form unique electrode structures to overcome the bottlenecks in low costs and fast charging. The lower tortuosity achieved by the open pores in the dry-printed (DP) electrode allows for a shorter Li+ diffusion pathway, which leads to better rate performance. The DP pouch cells exhibit higher capacity retention of 78% and 69% at 3C and 4C, respectively, compared with 67% and 52% for the slurry cast (SL) cells at the same rates. Moreover, the coating layer on the surface of active materials prevents the excess side reaction between active materials and electrolytes, which prolongs the cycle life of the DP cells. This manufacturing process is a roll-to-roll system with immense potential to be scaled up, providing a more efficient and economical way for battery manufacturing. In response to the growing demand for lithium-ion batteries (LIBs), we demonstrate a solvent-free manufacturing technology that can avoid toxic organic solvents and form unique electrode structures to overcome the bottlenecks in low costs and fast charging. The lower tortuosity achieved by the open pores in the dry-printed (DP) electrode allows for a shorter Li+ diffusion pathway, which leads to better rate performance. The DP pouch cells exhibit higher capacity retention of 78% and 69% at 3C and 4C, respectively, compared with 67% and 52% for the slurry cast (SL) cells at the same rates. Moreover, the coating layer on the surface of active materials prevents the excess side reaction between active materials and electrolytes, which prolongs the cycle life of the DP cells. This manufacturing process is a roll-to-roll system with immense potential to be scaled up, providing a more efficient and economical way for battery manufacturing. As the highly frequent extreme weather phenomena that happened in recent years alert us to the power of climate change, the control of greenhouse gases emission is urgent. In response to the United Nations Paris climate agreement (2015), the major emission countries and institutions such as the United States, the European Union, and China have claimed their net-zero pledge.1Rogelj J. Geden O. Cowie A. Reisinger A. Three ways to improve net-zero emissons targets.Nature. 2021; 591: 365-368Crossref PubMed Scopus (154) Google Scholar These policies have accelerated the lithium ion batteries (LIBs) market surge, and the boost could last for decades. As a result, the LIBs market will expand from about 160 GWh in 2018 to 1,200 GWh by 2030 based on forecasts.2Pillot C. The rechargeable battery market and main trends 2018–2030.International Congress for Battery Recycling. 2019https://rechargebatteries.org/wp-content/uploads/2019/02/Keynote_2_AVICENNE_Christophe-Pillot.pdfGoogle Scholar In the LIBs market, electrical vehicles (EVs) make up the largest market share and have huge potential. Due to the limitation of charging time and the cost of organic solvent in the electrode manufacturing process, the development of EVs is retarded. Current electrode manufacturing technology uses a slurry of active materials (AMs), conductive carbon, binders, and organic solvent coated on a metallic substrate. 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The energy-dispersive X-ray spectroscopy (EDS) mapping of fluorine in Figures 1A and 1B also proves the uniform spatial distribution of PVDF. The presence of carbon in the surface coating layer is also confirmed by the Raman spectrum in Figure S3. After the electrostatic spraying, thermal activation, and calendering, the surface morphology of the DP electrode shows a significant difference from the SL electrodes.23Ludwig B. Zheng Z. Shou W. Wang Y. Pan H. Solvent-Free Manufacturing of electrodes for lithium-ion batteries.Sci. Rep. 2016; 6: 23150https://doi.org/10.1038/srep23150Crossref PubMed Scopus (110) Google Scholar,29Liu J. Ludwig B. Liu Y. Zheng Z. Wang F. Tang M. Wang J. Wang J. Pan H. Wang Y. Scalable dry printing manufacturing to enable long-life and high energy lithium-ion batteries.Adv. Mater. Technol. 2017; 2https://doi.org/10.1002/admt.201700106Crossref PubMed Scopus (22) Google Scholar,30Liu J. Ludwig B. Liu Y. Pan H. Wang Y. 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The significant pores and gaps between the particles could increase the electrolyte wettability and enhance the Li+ exchange contact interface between the AM and electrolyte phases. Figures 1E and 1F show the detailed cross-section microstructure inside the electrode prepared by the ion polishing. The C65 and PVDF form the “conductive binder agglomeration (CBA)” clusters, which bridge the AM particles in the DP electrode.23Ludwig B. Zheng Z. Shou W. Wang Y. Pan H. Solvent-Free Manufacturing of electrodes for lithium-ion batteries.Sci. Rep. 2016; 6: 23150https://doi.org/10.1038/srep23150Crossref PubMed Scopus (110) Google Scholar These CBA clusters can provide enough bonding strength for the DP electrode while not filling most of the space between the AM particles like the microstructure in the SL electrode (Figure 1F).32Ludwig B. Liu J. Chen I.M. Liu Y. Shou W. Wang Y. Pan H. 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The extensive nano-size C65 powder on the surface works as a carbon coating layer, which could improve the local conductivity for the single particle and prevent the surface phase transformation during cycling.33Phattharasupakun N. Wutthiprom J. Duangdangchote S. Sarawutanukul S. Tomon C. Duriyasart F. Tubtimkuna S. Aphirakaramwong C. Sawangphruk M. Core-shell Ni-rich NMC-nanocarbon cathode from scalable solvent-free mechanofusion for high-performance 18650 Li-ion batteries.Energy Storage Mater. 2021; 36: 485-495https://doi.org/10.1016/j.ensm.2021.01.032Crossref Scopus (29) Google Scholar,34Ren D. Yang Y. Shen L. Zeng R. Abruña H.D. Ni-rich LiNi0.88Mn0.06Co0.06O2 cathode interwoven by carbon fiber with improved rate capability and stability.J. Power Sources. 2020; 447https://doi.org/10.1016/j.jpowsour.2019.227344Crossref Scopus (20) Google Scholar,35Chen G. Peng B. Han R. Chen N. Wang Z. Wang Q. A robust carbon coating strategy toward Ni-rich lithium cathodes.Ceram. 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The gradient binder distribution is caused by the capillary effect, which would result in binder migration during solvent evaporation.31Font F. Protas B. Richardson G. Foster J.M. Binder migration during drying of lithium-ion battery electrodes: modelling and comparison to experiment.J. Power Sources. 2018; 393: 177-185https://doi.org/10.1016/j.jpowsour.2018.04.097Crossref Scopus (75) Google Scholar,36Müller M. Pfaffmann L. Jaiser S. Baunach M. Trouillet V. Scheiba F. Scharfer P. Schabel W. Bauer W. Investigation of binder distribution in graphite anodes for lithium-ion batteries.J. Power Sources. 2017; 340: 1-5https://doi.org/10.1016/j.jpowsour.2016.11.051Crossref Scopus (123) Google Scholar,37Jaiser S. Kumberg J. Klaver J. Urai J.L. Schabel W. Schmatz J. Scharfer P. Microstructure formation of lithium-ion battery electrodes during drying – an ex-situ study using cryogenic broad ion beam slope-cutting and scanning electron microscopy (Cryo-BIB-SEM).J. 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Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are used to confirm the composition uniformity and thermal stability of the DP electrodes. In Figure S4A, the DP and SL electrodes show 89.47% and 87.91% weight retention, respectively, after 700°C, which represents the similar ratio of AM (NMC 622 is stable at 700°C) in the electrodes.40Bai Y. Hawley W.B. Jafta C.J. Muralidharan N. Polzin B.J. Belharouak I. Sustainable recycling of cathode scraps via Cyrene-based separation.Sustain. Mater. Technol. 2020; 25https://doi.org/10.1016/j.susmat.2020.e00202Crossref Scopus (31) Google Scholar The weight ratio of graphite in anodes cannot be identified by the TGA test because the burning temperatures of graphite and C65 are overlapped (Figure S4B). For the DSC analysis in Figure S4C, the small heat flow peaks between 400°C and 500°C and is corresponding to the decomposition of PVDF, while the higher peaks between 500°C and 600°C represent the burning of C65.41Ribeiro J.S. Ribeiro A.A. Cardoso C.X. Preparation and characterization of PVDF/CaCO3 composites.Mater. Sci. Eng. B. 2007; 136: 123-128https://doi.org/10.1016/j.mseb.2006.09.017Crossref Scopus (80) Google Scholar,42Freiberg A.T.S. Sicklinger J. Solchenbach S. Gasteiger H.A. Li2CO3 decomposition in Li-ion batteries induced by the electrochemical oxidation of the electrolyte and of electrolyte impurities.Electrochim. Acta. 2020; 346https://doi.org/10.1016/j.electacta.2020.136271Crossref Scopus (72) Google Scholar The DC shows a delayed heat flow peak (564°C), compared with the SC (551°C), which could be caused by the heat exchange through the surface of coated C65 with the high heat capacity NMC particles. Figure S4D shows the C65 peak is merged with the graphite peak in the DA, which is caused by the C65 coating on the surface of graphite particles and burned as an entirety. The graphite heat flow peak is significantly delayed in the DA (765°C), compared with the SA (706°C).43Ma X. Chen M. Chen B. Meng Z. Wang Y. High-performance graphite recovered from spent lithium-ion batteries.ACS Sustainable Chem. Eng. 2019; 7: 19732-19738https://doi.org/10.1021/acssuschemeng.9b05003Crossref Scopus (92) Google Scholar The C65 agglomerations in the SA could ignite the graphite particles and accelerate the burnout process. Overall, the microstructure of DP electrodes could help to delay the thermal runaway with higher burning temperatures.44Song L. Zheng Y. Xiao Z. Wang C. Long T. Review on thermal runaway of lithium-ion batteries for electric vehicles.J. Electron. Mater. 2022; 51: 30-46https://doi.org/10.1007/s11664-021-09281-0Crossref Scopus (16) Google Scholar Mercury intrusion porosimetry (MIP) was applied to characterize the pore size distribution in the cathode electrodes. In Figure 2A, the SC shows a significant peak between 0.1 and 0.2 μm, which is corresponding to the nanopores in the slurry CBD phase. The peak near 1 μm of the black line represents the open pores between the NMC and the CBD phase. However, the DP electrode exhibits a broader and lower peak at the sub-micro range and a higher amount of larger pores between 1 and 10 μm. The large open pores (over 10 μm) observed from the SEM images cannot be distinguished from the voids between samples (electrodes need to be cut into small pieces for the MIP test).45Radloff S. Kremer L.S. Hoffmann A. Wohlfahrt-Mehrens M. Characterization of structured ultra-thick LiNi0.6Co0.2Mn0.2O2 lithium-ion battery electrodes by mercury intrusion porosimetry.Mater. 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