ORNL team tailors the structure of carbon black from waste tires to create higher performance carbon anode material for Li-ion batteries
Researchers at Oak Ridge National Laboratory (ORNL) have tailored the microstructural characteristics of carbon black recovered from discarded tires to produce a higher performance, low-cost carbon anode material for Li-ion batteries.
Electrochemical studies reported in their paper published in the journal RSC Advances showed that the recovered-carbon-based anode had a a reversible capacity of nearly 390 mAh/g of carbon anode after 100 cycles—exceeding the best properties of commercial graphite. Researchers attribute this to the unique microstructure of the tire-derived carbon. Anodes made with the sulfonated tire-rubber-derived carbon and a control tire-rubber-derived carbon exhibited an initial coulombic efficiency of 71% and 45%, respectively.
The team suggested that the success in producing a higher performance carbon material from waste tire rubber for potential use in energy storage applications adds a new avenue to tire rubber recycling.
The ORNL technique uses a proprietary pretreatment to recover pyrolytic carbon black material, which is similar to graphite but man-made. Micronized tire rubber was first digested in a hot oleum bath to yield a sulfonated rubber slurry that was then filtered, washed, and compressed into a solid cake.
Pyrolysis of the cake in a nitrogen atmosphere yielded sulfonated rubber powder; when the recovered hard carbons are treated properly before or during carbonization, they can yield very high surface area pyrolytic carbon black composites. To avoid potential impurities such as metal particles in the carbon powder, the powdered rubber can be washed with an acid solution during the recovery process.
The chemical pretreatment of rubber produced a carbon monolith with higher yield than that from the control (a fluffy tire-rubber-derived carbon black).
The carbon monolith showed a very small volume fraction of pores of widths 3–5 nm, prominent nanoporosity (pore width < 2 nm), reduced specific surface area, and an ordered assembly of graphitic domains.
This technology addresses the need to develop an inexpensive, environmentally benign carbon composite anode material with high-surface area, higher-rate capability and long-term stability.—Amit Naskar, lead author
ORNL plans to work with US industry to license this technology and produce lithium-ion cells for automobile, stationary storage, medical and military applications.
ORNL has posted the solicitation titled, “Low-Cost, Graphite Anodes For Lithium-Ion Batteries,” in FedBizOpps. The solicitation (#ORNL-TT-2014-08) closes 15 Sept. Other potential uses include water filtration, gas sorption and storage.
The researchers are working on a pilot manufacturing process to scale up the recovery of material and demonstrate applications as anodes for lithium-ion batteries in large-format pouch cells. Researchers expect these batteries to be less expensive than those manufactured with commercial carbon powders.
The research on conversion of recycled tires to graphite powders was funded by the laboratory’s Technology Innovation Program while the research on battery fabrication and electrochemical testing was sponsored by DOE’s Office of Basic Energy Sciences, Materials Sciences and Engineering Division. Transmission electron microscopy research was supported by ORNL’s Center for Nanophase Materials Sciences, a DOE Office of Science user facility.
Naskar, Amit K. and Bi, Zhonghe and Li, Yunchao and Akato, Sam K. and Saha, Dipendu and Chi, Miaofang and Bridges, Craig A. and Paranthaman, M. Parans (2014) “Tailored recovery of carbons from waste tires for enhanced performance as anodes in lithium-ion batteries,” RSC Adv. doi: 10.1039/C4RA03888F