Progress 07/01/22 to 02/28/23

Outputs
Target Audience:A target audience is lithium ion battery manufacturers who will benefit from a domestic supply chain replacement for active anode materials. Another target audience is biomass raw material suppliers who could supply materials to COnovate for processing/upscalinginto eCOphite materials that can be used as active anode materials in lithium ion batteries. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Dr. Marvin Schofield and Dr. Carol Hirschmugl worked as mentors with Intern Adam Opperman, training him to gain proficiency in sample preparation, collecting a variety of analytical data and learning how to analyze the data. Adam Opperman is a graduate student in Physics at the University of Wisconsin-Milwaukee, and earning his graduate degree in parallel with working at COnovate as an intern. Learning how to collect, organize, evaluate and analyze large data sets for COphite material is the basis of his project. How have the results been disseminated to communities of interest?Data has been shared at the International Battery Seminar in Orlando, Florida and at the NATBATT annual meeting in Pheonix Arizona. Battery experts including battery engineers, and other battery experts regularly attend these meetings to learn about ongoing and new developments in the battery ecosystem. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1.) Major Activities Completed Objective A: Prepare and evaluate eCOphite materials from bio-renewable crystalline nanocellulose (CNC) raw materials. Two CNC materials were evaluated; both generated eCOphite material with one material generating slightly better GmO component. The iterative process to develop appropriate material processing procedures was pursued. Materials were generated with a variety of processing recipes, including distinct polysacharide components such as disaccharides and monosaccharides, involving in some cases surrogates from easily attainable sources. Material and recipe with the most pronounced GmO signatures were chosen for further iterations. Objective B: Prepare and evaluate eCOphite materials from bio-renewable lignin used as a raw carbon source material.?A similar procedure to that described for Objective A was implemented to screen and evaluate a variety of lignin samples and recipes. The lignin samples were chosen to test the impact of impurities with respect to impact on eCOphite material production and performance. It is critical to evaluate and determine the acceptable specifications including impurities of raw feedstocks and correlate to final eCOphite material for battery applications. Activities focused on highest and lowest impurity level feedstocks. Combinations of lignin and CNC, and a raw material from wood with an original combination of lignin, cellulose and hemicellulose were all evaluated through the process.? Objective C: Scale and evaluate the eCOphite materials from CNC and lignin and employ in lithium-ion half cells to demonstrate the eCOphite material electrochemical performance. A recipe was promoted from each objective A and B and scaled to produce 10g final batches. 10g is sufficient for material evaluation with analytical and electrochemical testing. 2.) Data Collected All data for the various processing conditions and screening results was collected in Uncountable, a machine informatics/machine learning platform that we have implemented to help determine the best quality eCOphite materials to scale and test in lithium-ion batteries. Objective A and B: Onset temperatures and temperature windows for mass-loss events were identified from thermal gravimetric analysis profiles and were used to guide the design of heating profiles for subsequent furnace operations to produce and optimize the conversion percentage of the GmO component within the eCOphite materials. The samples were evaluated with transmission electron microscopy (TEM) diffraction techniques (and later x-ray diffraction (XRD)) to characterize the GmO component (or lack thereof) of the processed material. Evaluating these materials included collecting diffraction data from both TEM and XRD, where the XRD characterization expanded our capabilities from microscopic (TEM-based) to bulk (XRD-based) measurements that are critical for scaling. Chemical functionality was evaluated using vibrational spectroscopy to detect the functional groups present in the samples. Since the final product is a battery grade eCOphite material, additional materials parameters are collected for selected eCOphite materials, to determine how similar they are to battery grade materials that lead to high quality electrodes. They include particle size, preferably below 25 micrometers in all dimensions; specific surface area, preferably below 10 m2/g and tap density, preferably approximately 1 g/cm3. Objective C: The TEM and IR data support that the scaled materials provide similar quality eCOphite materials to the smaller development batches. The electrochemical performance of the larger materials was collected, since the value of the product is how it performs in the final application. A critical aspect of this project is to link electrochemical performance to material characteristics to identity promising candidates for further development for producing cost effective, battery grade eCOphite active anode materials - the primary goal of this proposal. This data was produced both at COnovate and at a third-party validator, which is critical for validation to attract customers. 3.) Results Objective A and B: The TEM line profiles illustrate that multiple material preparations can show diffraction spacings that correspond to GmO. Optimized thermal processing and recipe conditions show mature GmO features present in the eCOphite material that is anticipated to lead to better battery performance. Spectra from eCOphite materials generated from CNC- and lignin-based routes were compared to representative IR spectra from GO-based COphite material. The IR data contains vibrational signatures consistent with GmO functional groups and that there is a lack of functional groups associated with hydrogen, consistent with COphite materials generated from inorganic graphite-derived routes. The broad weak signature between 1000-1500 cm-1 is indicative of C-O functional groups associated with dioxetane, while the lack of broad signatures between 3000-3600 cm-1, and lack of all signatures between 2700-3000 cm-1 show that the COphite and eCOphite materials do not contain hydrogen-containing functional groups. There is a positive correlation (>.80 correlation for these output parameter pairs) between initial electrochemical performance (specific capacity and Coulombic efficiency) and crystallographic properties (c-axis figure of merit and spacing, both indicators of GmO quality) of lignin-based eCOphite materials processed under a variety of thermal profiles and conditions. Objective C: As materials were scaled, COnovate conducted full cell testing with Polaris Laboratories. This testing consisted of first validating our materials in a slurry for battery electrodes. This testing was completed using a 25% (e)COphite/ 75% graphite mixtures and compared to a 100% graphite slurry. After completing the slurry testing, single layer pouch cells were produced to demonstrate the performance advantages of eCOphite blend electrode over the current 100% graphite technology. 4.) Key Outcomes or Other Accomplishments Realized. Objective A and B:. By drawing Key Parameters from synthesis, core analytic methods (XRD in this case), and final application performance metrics, we can, for example, iteratively improve the material properties with respect to performance in lithium-ion half-cell batteries. For the materials generated to date, the lignin-derived eCOphite materials are closer to the desirable battery grade properties than the CNC-derived eCOphite materials with high specific capacity and the highest first coulombic efficiency as compared to the other materials tested. The lignin-based materials also had low surface area and tap densities greater than 1g/cm3. Objective C: The rheology profile of the 25% eCOphite - 75% graphite slurry shows an identical rheology profile to that of the 100% graphite slurry. This result shows that incorporating 25% eCOphite materials into current battery slurries would yield a similar viscosity and is predicted to process similarly to a 100% graphite slurry. High (2C) charge rate cycling data comparing the performance of both a 100% graphite electrode was compared to a 25% eCOphite blended with graphite. This testing shows superior performance of the eCOphite when cycled using high charge rates. The graphite cells show a significant decrease in capacity in the first 50 cycles and after 100 cycles, only retain 45% of their initial capacity. With eCOphite materials showing compatibility with current lithium-ion battery production processes and having more cycle stability at higher charge rates, this material should be desirable as both an additive and full replacement to current graphite anode materials when high charge rates are needed.

Publications