Session: Government Agency Student Posters

Paper Number: 174330

Novel Biodegradable Poly-Lysine Crosslinked Multi-Carbonyl Polymers as High-Performance Cathode Materials for Sodium/potassium-Ion Batteries. 

As the climate crisis intensifies, there is an urgent global imperative to develop environmentally friendly and sustainable electrode materials for energy storage applications. Biomolecules—such as proteins, peptides, and amino acids—have emerged as promising alternatives to conventional metal oxide and hydroxide-based systems due to their intrinsic safety, non-toxicity, abundance, and ease of device fabrication. However, many existing organic electrode materials, particularly those based on aliphatic backbones, suffer from poor biodegradability, thereby posing significant challenges for end-of-life waste management.

To address this critical issue, recent research has focused on the development of polypeptide-based batteries that maintain operational stability but can undergo on-demand degradation under acidic conditions at the end of their lifecycle, producing environmentally benign amino acids and other non-toxic byproducts. Building upon this concept, we introduce a novel class of biodegradable polylysine-crosslinked polycarbonyl polymers as high-performance cathode materials for advanced sodium-ion (SIBs) and potassium-ion batteries (KIBs).

The central innovation of this work lies in the integration of excellent electrochemical performance with intrinsic biodegradability through precise molecular design. Specifically, we synthesized these polymers by crosslinking biocompatible and biodegradable polylysine with various polycarbonyl dianhydride monomers, including 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), and pyromellitic dianhydride (PMDA). The resulting polymers feature robust, insoluble networks formed via stable imide linkages between the amino groups of polylysine and the anhydride functionalities, effectively mitigating the dissolution issues that plague small organic molecules in battery electrolytes. Moreover, the material’s biodegradability is primarily derived from the controlled hydrolysis of the polylysine peptide backbone under mild acidic conditions. This design strategy not only enhances electrochemical performance but also aligns closely with principles of the circular economy and sustainable materials science.

The target polymers were synthesized via crosslinking polymerization, and their structures were thoroughly characterized using a suite of techniques. Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of characteristic functional groups and bonding motifs, while solid-state nuclear magnetic resonance (NMR) elucidated the molecular architecture. Thermogravimetric analysis (TGA) assessed thermal stability and compositional integrity, scanning electron microscopy (SEM) revealed morphological features and nanostructures, and X-ray diffraction (XRD) provided insights into crystallinity. Surface elemental composition and oxidation states were further analyzed via X-ray photoelectron spectroscopy (XPS).

Electrochemical performance was evaluated using coin-type half-cells. Cyclic voltammetry (CV) revealed redox behavior, galvanostatic charge-discharge (GCD) tests assessed specific capacity and voltage profiles, and rate performance testing demonstrated capacity retention at high current densities. Long-term cycling tests evaluated durability, while galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) were employed to investigate ion diffusion kinetics and charge transfer resistance. These methods collectively elucidated the underlying mechanisms of the material’s superior performance. Future work will incorporate in situ characterization techniques (e.g., in situ XRD and FTIR) to monitor ion–polymer interactions during cycling for deeper mechanistic understanding.

Preliminary results indicate that PLLPTCDA—polylysine crosslinked with PTCDA—exhibits outstanding high-rate capability and excellent long-term cycling stability. In sodium-ion batteries, PLLPTCDA delivered a specific capacity of approximately 125 mAh g⁻¹ at a current density of 0.05 A g⁻¹ and retained about 75 mAh g⁻¹ even at 5 A g⁻¹. Remarkably, over 1500 stable cycles were achieved at 1 A g⁻¹. This superior performance is attributed to the robust molecular architecture of the crosslinked framework, its favorable nanostructure, and rapid ion diffusion kinetics. PTCDA-based materials are already known for their high theoretical capacity, stable redox activity, and excellent cycling performance, and their incorporation into a biodegradable polymer matrix represents a synergistic advancement.

Overall, this work represents a significant step toward the realization of next-generation green energy storage systems that are both high-performing and environmentally responsible. It not only introduces a new class of degradable, high-efficiency cathode materials but also provides a versatile design strategy for future development of sustainable and customizable battery technologies.

Presenting Author: Chengxiang Chen University of Miami

Presenting Author Biography: Chengxiang Chen is a Ph.D. student at the University of Miami, focusing on the synthesis of organic electrode materials for sodium- and potassium-ion batteries. His research involves molecular design, organic synthesis, and electrochemical evaluation of sustainable energy storage systems.

Authors:

Chengxiang Chen University of Miami
Chao Luo University of Miami