Progress 08/15/19 to 10/14/20
Outputs
Target Audience:The target audience will be battery researchers and battery materials customers that are seeking newhigh capacity durable anode material for lithium ion batteries. The initial target markets for the battery materialsare military, aerospace and consumer automotive. Suppliers of micro-algae may also be interested in the potential energy storage markets for their bio-materials. Changes/Problems:A no-cost extension was requested in early 2020 in order to have more time to collect full cell data and mitigate issues with lab-closures due to COVID. Equipment issues resulted in impedance analysis of full cells to not be carried. However, standard half cell and full cell voltage cycling and discharge capacity evaluation was carried out. What opportunities for training and professional development has the project provided?pH Matter was able to hire chemical engineering interns from Ohio State University that served in a engineering technician role on the project. The interns learned methods for preparing battery materials and test procedures to measure battery performance. How have the results been disseminated to communities of interest?Scientists from pH Matter planto attend battery conferences in the near future to share the project details, however, due to COVID restrictions conference attendance has been delayed. What do you plan to do during the next reporting period to accomplish the goals?pH Matterplans to prepare a Phase II SBIR proposal in order to further improve the biomorphic silicon battery performance.
Impacts
What was accomplished under these goals?
Superior silicon (Si) based battery anodes enable better Li-ion batteries (LIBS), less liable to fail, longer lasting, and with higher specific energy. Standard chemical synthesis methods for nano Si cannot create the best battery Si anode today., We have shown that algae, with our proprietary process, creates more durable and higher specific energy Si anode materials for LIBS. With our Phase I SBIR funding, pH Matter (PHM ) developed a process that converts the uniform nano structure of micro-algae (diatoms) into highly stable porous Si and demonstrated improved battery cycle life compared to commercial nano Si used in LIB anodes. Our research proves natural materials can be used for better LIB materials synthesis. Nature, has developed materials that can be of great utility for human needs. The ability of biological organisms to self-assemble intricate three-dimensional structures in large volumes to provide a uniform product enables agriculture to deliver materials of great value to LIB manufacturers. Recent materials research in nano-technology has proven nature to be the ideal model for materials synthesis. With the advantage of time, nature through the process of evolution, has been the most successful laboratory to have ever existed. The ability of biological organisms to self-assemble intricate three-dimensional structures in large volumes provides a blue print for materials scientist to harness for future methods of commercial nano-assembly. Diatoms, a 3-dimensional natural silica biomaterial generated from single cell algae with unique nano and micro-morphologies and patterns has been shown to have several exceptional structural, mechanical, optical, and chemical properties optimized through millions of years of evolution. PHM demonstrated in our Phase I SBIR that 3-dimensional natural silica biomaterial from single cell algae with unique nano and micro morphologies and structures have significant advantages over Si produced from expensive and dangerous chemical precursors such as silane, a colorless, flammable, poisonous gas that can explode in air. Si is used in semiconductors, solar PV, and other applications and is being used in next-generation LIB anodes. Today standard commercial Si suffers from severe degradation during LIB charge and discharge cycles so major improvements are needed in the Si morphology (shape) and micro-structure (size) to develop better anode materials. Our trade-secret biomorphic shape-preserving reactions convert uniform nano-porous diatom silica structures into optimum shape, size and porosity for improved Si anode cyclability versus conventional chemical synthesis of Si particles. The intricate nanostructures that micro-algae possess cannot be economically replicated using synthetic chemical production methods that are the industry standard today. Industrial processes to create nano structured Si are expensive ($1,000's/kg) , use toxic chemicals such as hydrofluoric acid (HF) to chemically etch porous structures, or use silane to grow structures from catalysts, and can be expensive and difficult to scale up to high volume manufacturing. Commercial adoption of electric vehicles is limited in part by the low specific energy of today's LIBs. Achieving better battery performance targets requires significant improvement in major LIB cell components, including the anode. PHM's new biomimetic (mimicking nature) approach could achieve desired power and energy goals, by exceeding today's conventional Si materials limits and improving Si anode lifetime, cycle fade, charge/ discharge rate, and efficiency. Million mile Li-ion batteries being developed by Tesla, GM, and Chinese vendors focus mainly on cathode improvements to extend battery lifetimes. Their strategies include limiting use of Ni and Co in the cathode, expensive elements which reduce battery cycle life. Improvements in cathode stability and reduction in expensive Ni and Co usage, combined with PHM's focus on high specific energy Si anodes, will result in lower cost LIBS for E-transport including air, land, and sea platforms as well as micro-grid and main grid. Figure 1 shows the value of our bio--ag based innovation versus expensive and toxic based nano-Si technology. Our Phase I SBIR results show less than 27% decline in battery capacity over 50 charge discharge cycles versus 90% for commercial nano Si. PHM's advanced bio-morphic Si anode materials enables us to develop commercial Si anodes with Phase II funding that will be price competitive with graphite anodes on an energy basis ($15/kWh). Some of the key goals of the project were the following: The major goals for this project are as follows: • Demonstrate a cost effective process for converting micro-algae to active battery materials. • Demonstrate a process to stabilize the battery materials in the electrochemical cell format. • Demonstrate improvements in the battery cyclability of micro-algae precursors. • Demonstrate a full cell energy density greater than 350 Wh/kg based on the full cell components at 50 cycles. The following list of Phase I objectives were demonstrated during the project: PHM was able to demonstrate the economic conversion of commercial bio-silica diatom frustules while retaining porosity of the final silicon product. pH Matter developed methods to remove/clean the organic lipids of the micro-algae to produce a high purity silica frustule that was then converted to phase pure silicon which was confirmed by x-ray diffraction techniques. PHM used a moderate temperature metallurgical reaction to obtain the final biomorphic silicon product. PHM demonstrated a process to uniformly carbon coat the silicon obtained from bio-morphic conversion. This carbon coating was found to further improve silicon cycle life. PHM developed the capability to carbon coat the biomorphic silicon using low-cost gas phase carbon in continuous rotary reactors. PHM demonstrated improvements in the cyclability in the battery anodes produced from the bio-morphic silicon in both half-cell and full cell measurements when compared to commercial grade nano-silicon. These cells were prepared in a high energy density format (>350 Wh/kg). With certain species of micro-algae, the cycle life was improved by a factor of 5X.
Publications
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