Novel Polymeric Morphologies as Positive Electrodes in Lithium-Ion Batteries

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Growing demands for next-generation energy storage technology for utilization in consumer and grid energy storage applications have prompted a re-evaluation of lithium-ion batteries (LIBs), which are the preeminent electrochemical energy storage technology. Due to the cost and environmental impact of transition metals used in the positive electrode, researchers are investigating novel materials and processing techniques to introduce new chemistries and electrode architectures into LIBs. Herein, we propose a novel materials-processing platform to develop application-specific polymeric electrode architectures for next-generation LIBs. Organic radical polymers are of interest as an alternative positive electrode for LIBs. In particular, poly (2,2,6,6 tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) has garnered attention for its relative ease of synthesis and its fast charge-discharge kinetics. However, before implementation as an electrode, PTMA requires a significant amount of conductive additive and binder to remedy its electronically insulating polymeric backbone and its solubility in organic electrolytes, all of which decreases the gravimetric performance of PTMA. The multiphasic processing platform presented here utilizes the precipitation of PTMA in turbulent solvent-nonsolvent induced phase separation to introduce a soft dendritic colloid (SDC) morphology. Characterized by fractal branching and nanofibrillar contact splitting, the morphology of PTMA SDCs rectifies the solubility and electronic conductivity limitations associated with PTMA electrodes by introducing improved surface area and self-adhesive properties. Rate capability and cycling stability improvements are expected from PTMA SDC electrodes compared to benchmark slurry cast PTMA electrodes due to more efficient contact with conductive additives and reduced electrolyte solubility in PTMA SDCs. This hypothesis is tested and reported upon here through electrochemical analysis via cyclic voltammetry and galvanostatic charge and discharge experiments of PTMA SDC and benchmark slurry cast PTMA positive electrodes in half-cell environments against reference lithium metal electrodes.