Stabilized lithium metal powder (SLMP) has been applied during battery assembly to effectively prelithiate high capacity (1500–2500 mAh/g) silicon–carbon nanotube (Si-CNT) anodes, eliminating the ...20–40% first cycle irreversible capacity loss. Pressure-activation of SLMP is shown to enhance prelithiation and enable capacity matching between Si-CNT anodes and lithium nickel cobalt aluminum oxide (NCA) cathodes in full batteries with minimal added mass. The prelithiation approach enables high energy density NCA/Si-CNT batteries achieving >1000 cycles at 20% depth-of-discharge.
Fullerenes are increasingly being used in medical, environmental, and electronic applications due to their unique structural and electronic properties. However, the energy and environmental impacts ...associated with their commercial-scale production have not yet been fully investigated. In this work, the life cycle embodied energy of C60 and C70 fullerenes has been quantified from cradle-to-gate, including the relative contributions from synthesis, separation, purification, and functionalization processes, representing a more comprehensive scope than used in previous fullerene life cycle studies. Comparison of two prevalent production methods (plasma and pyrolysis) has shown that pyrolysis of 1,4-tetrahydronaphthalene emerges as the method with the lowest embodied energy (12.7 GJ/kg of C60). In comparison, plasma methods require a large amount of electricity, resulting in a factor of 7−10× higher embodied energy in the fullerene product. In many practical applications, fullerenes are required at a purity >98% by weight, which necessitates multiple purification steps and increases embodied energy by at least a factor of 5, depending on the desired purity. For applications such as organic solar cells, the purified fullerenes need to be chemically modified to 6,6-phenyl-C61-butyric acid methyl ester (PCBM), thus increasing the embodied energy to 64.7 GJ/kg C60-PCBM for the specified pyrolysis, purification, and functionalization conditions. Such synthesis and processing effects are even more significant for the embodied energy of larger fullerenes, such as C70, which are produced in smaller quantities and are more difficult to purify. Overall, the inventory analysis shows that the embodied energy of all fullerenes are an order of magnitude higher than most bulk chemicals, and, therefore, traditional cutoff rules by weight during life cycle assessment of fullerene-based products should be avoided.
Multiplex digital PCR (dPCR) enables noninvasive and sensitive detection of circulating tumor DNA with performance unachievable by current molecular-detection approaches. Furthermore, picodroplet ...dPCR facilitates simultaneous screening for multiple mutations from the same sample.
We investigated the utility of multiplex dPCR to screen for the 7 most common mutations in codons 12 and 13 of the KRAS (Kirsten rat sarcoma viral oncogene homolog) oncogene from plasma samples of patients with metastatic colorectal cancer. Fifty plasma samples were tested from patients for whom the primary tumor biopsy tissue DNA had been characterized by quantitative PCR.
Tumor characterization revealed that 19 patient tumors had KRAS mutations. Multiplex dPCR analysis of the plasma DNA prepared from these samples identified 14 samples that matched the mutation identified in the tumor, 1 sample contained a different KRAS mutation, and 4 samples had no detectable mutation. Among the tumor samples that were wild type for KRAS, 2 KRAS mutations were identified in the corresponding plasma samples. Duplex dPCR (i.e., wild-type and single-mutation assay) was also used to analyze plasma samples from patients with KRAS-mutated tumors and 5 samples expected to contain the BRAF (v-raf murine sarcoma viral oncogene homolog B) V600E mutation. The results for the duplex analysis matched those for the multiplex analysis for KRAS-mutated samples and, owing to its higher sensitivity, enabled detection of 2 additional samples with low levels of KRAS-mutated DNA. All 5 samples with BRAF mutations were detected.
This work demonstrates the clinical utility of multiplex dPCR to screen for multiple mutations simultaneously with a sensitivity sufficient to detect mutations in circulating DNA obtained by noninvasive blood collection.
Carbon nanotubes for lithium ion batteries Landi, Brian J.; Ganter, Matthew J.; Cress, Cory D. ...
Energy & environmental science,
01/2009, Volume:
2, Issue:
6
Journal Article
Peer reviewed
Lithium ion batteries are receiving considerable attention in applications, ranging from portable electronics to electric vehicles, due to their superior energy density over other rechargeable ...battery technologies. However, the societal demands for lighter, thinner, and higher capacity lithium ion batteries necessitate ongoing research for novel materials with improved properties over that of state-of-the-art. Such an effort requires a concerted development of both electrodes and electrolyte to improve battery capacity, cycle life, and charge-discharge rates while maintaining the highest degree of safety available. Carbon nanotubes (CNTs) are a candidate material for use in lithium ion batteries due to their unique set of electrochemical and mechanical properties. 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. In addition, CNTs have the capability to be assembled into free-standing electrodes (absent of any binder or current collector) as an active lithium ion storage material or as a physical support for ultra high capacity anode materials like silicon or germanium. The measured reversible lithium ion capacities for CNT-based anodes can exceed 1000 mAh g-1 depending on experimental factors, which is a 3times improvement over conventional graphite anodes. The major advantage from utilizing free-standing CNT anodes is the removal of the copper current collectors which can translate into an increase in specific energy density by more than 50% for the overall battery design. However, a developmental effort needs to overcome current research challenges including the first cycle charge loss and paper crystallinity for free-standing CNT electrodes. Efforts to utilize pre-lithiation methods and modification of the single wall carbon nanotube bundling are expected to increase the energy density of future CNT batteries. Other progress may be achieved using open-ended structures and enriched chiral fractions of semiconducting or metallic chiralities that are potentially able to improve capacity and electrical transport in CNT-based lithium ion batteries.
While disposal bans of lithium-ion batteries are gaining in popularity, the infrastructure required to recycle these batteries has not yet fully emerged and the economic motivation for this type of ...recycling system has not yet been quantified comprehensively. This study combines economic modeling and fundamental material characterization methods to quantify economic trade-offs for lithium ion batteries at their end-of-life. Results show that as chemistries transition from lithium-cobalt based cathodes to less costly chemistries, battery recovery value decreases along with the initial value of the raw materials used. For example, manganese-spinel and iron phosphate cathode batteries have potential material values 73% and 79% less than cobalt cathode batteries, respectively. A majority of the potentially recoverable value resides in the base metals contained in the cathode; this increases disassembly cost and time as this is the last portion of the battery taken apart. A great deal of compositional variability exists, even within the same cathode chemistry, due to differences between manufacturers with coefficient of variation up to 37% for some base metals. Cathode changes over time will result in a heavily co-mingled waste stream, further complicating waste management and recycling processes. These results aim to inform disposal, collection, and take-back policies being proposed currently that affect waste management infrastructure as well as guide future deployment of novel recycling techniques.
•The majority of recoverable value resides in the active materials of the cathode.•Changes in cathode result in high compositional uncertainty of the waste stream.•Cathode technology trajectory indicates reduced economic incentive to recycle LIBs.•Trade-offs in recovery priority exist for environmentally based metrics i.e. toxicity.
An approach to battery end-of-life (EOL) management is developed involving cathode refunctionalization, which enables remanufacturing of the cathode from EOL materials to regain the electrochemical ...performance. To date, the optimal end-of-life management of cathode materials is based on economic value and environmental impact which can influence the methods and stage of recycling. Traditional recycling methods can recover high value metal elements (e.g. Li, Co, Ni), but still require synthesis of new cathode from a mix of virgin and recovered materials. Lithium iron phosphate (LiFePO4) has been selected for study as a representative cathode material due to recent mass adoption and limited economic recycling drivers due to the low inherent cost of iron. Refunctionalization of EOL LiFePO4 cathode was demonstrated through electrochemical and chemical lithiation methods where the re-lithiated LiFePO4 regained the original capacity of 150–155 mAh g−1. The environmental impact of the new recycling technique was determined by comparing the embodied energy of cathode material originating from virgin, recycled, and refunctionalized materials. The results demonstrate that the LiFePO4 refunctionalization process, through chemical lithiation, decreases the embodied energy by 50% compared to cathode production from virgin materials.
•Commercial LiFePO4 cells were cycled to an end-of-life (EOL) state.•Capacity fade with cycling was determined to be due to lithium loss.•LiFePO4 capacity was recovered through electrochemical and chemical re-lithiation.•Re-lithiation is a process to refunctionalize cathode to regain performance.•Refunctionalization has less embodied energy than material synthesis or recycling.
Single-wall carbon nanotubes (SWCNTs) synthesized via laser vaporization have been dispersed using chlorosulfonic acid (CSA) and extruded under varying coagulation conditions to fabricate ...multifunctional wires. The use of high purity SWCNT material based upon established purification methods yields wires with highly aligned nanoscale morphology and an over 4× improvement in electrical conductivity over as-produced SWCNT material. A series of eight liquids have been evaluated for use as a coagulant bath, and each coagulant yielded unique wire morphology based on its interaction with the SWCNT-CSA dispersion. In particular, dimethylacetamide as a coagulant bath is shown to fabricate highly uniform SWCNT wires, and acetone coagulant baths result in the highest specific conductivity and tensile strength. A 2× improvement in specific conductivity has been measured for SWCNT wires following tensioning induced both during extrusion via increased coagulant bath depth and during solvent evaporation via mechanical strain, over that of as-extruded wires from shallower coagulant baths. Overall, combination of the optimized coagulation parameters has yielded acid-doped wires with the highest reported room temperature electrical conductivities to date of 4.1–5.0 MS/m and tensile strengths of 210–250 MPa. Such improvements in bulk electrical conductivity can impact the adoption of metal-free, multifunctional SWCNT materials for advanced cabling architectures.
Germanium nanoparticles (Ge-NPs) were synthesized through a one-step chemical vapor deposition process and were included in a hybrid free-standing single-wall carbon nanotube (SWCNT) electrode. The ...Ge-NPs were characterized through scanning electron microscopy and Raman spectroscopy to confirm the presence of crystalline nanoparticles with average diameters of 60 nm. Electrochemical testing of the Ge-NPs shows high reversible lithium ion capacity up to 900 mAh g–1 and a Coulombic efficiency of 96% on the first cycle, with capacities realizing 1000 mAh g–1 and a Coulombic efficiency of 98% on the second cycle. The use of SWCNTs to provide a stable nanoscale electrical network to support Ge-NPs resulted in a hybrid three-dimensional free-standing electrode, which is an attractive alternative to the conventional composite-current collector approach. The Ge-NP:SWCNT hybrid electrode with thin film titanium contacts produced electrode capacities of 983 mAh g–1 versus Li/Li+ up to 3 V. The higher anode capacity for the hybrid is maintained at modest cycling rates up to 1C. The pairing of the hybrid electrode with a commerical LiFePO4 cathode showed excellent performance with anode capacities of 800 mAh g–1 over a 1 V discharge range. Even at higher discharge rates, up to 1C, the anode energy density changes by only 8.5%. Thus, this demonstrates the first full battery comprising a free-standing Ge-based anode with a high power cathode exhibiting improved energy and power density.
Wires formed of densified as-received and purified commercially available Carbon Nanotube (CNT) sheet material as well as a laid CNT wire were tested for long-term stability in a saltwater ...environment under an applied electrical bias. Tafel electrochemical measurements showed increased chemical stability for the CNT samples over copper, with the corrosion resistance of CNT samples showing further improvement after purification. Under constant DC voltage biases of 2.50 V, CNT materials show improvements in failure time by as much as 108 times over comparable diameter copper wires, with further improvement over copper at lower applied voltages due to material stability and an absence of gas evolution. Shear forces resulting from gas formation was found to significantly contribute to the failure of CNT wires at elevated voltages compared to chemical corrosion typical in copper wires.
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•The long-term stability of carbon nanotube conductors under electrical bias in seawater is measured and compared to copper.•CNT wires fabricated from densified as-received and purified CNT sheet material as well as twisted CNT fibers examined.•Stability under 1.0–2.5 V constant voltage and 5 mA constant current examined.•Constant voltage testing of CNT wires show improvement in failure times by up to 108 times more than Cu.
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