Collaborative Research: An Integrated Experimental and Computational Approach to Reveal Adsorption-Catalysis Cathode Design Principles for Na-S Batteries

Rechargeable batteries are essential for diminishing reliance on fossil fuels, mitigating greenhouse gas emissions, and achieving a net-zero carbon economy. This project aims to enhance the performance of room temperature sodium-sulfur (Na-S) batteries, which offer a promising, cost-effective, and environmentally friendly energy storage solution. Currently, widely used lithium faces challenges of scarcity and supply chain disruptions.

In contrast, sodium is abundantly available domestically, providing a sustainable and low-cost alternative for electric vehicles (EVs) and large-scale grid applications. Na-S batteries have significant potential due to their high theoretical capacity, energy density, and abundance of sodium and sulfur. However, a critical issue hindering their widespread adoption is the "shuttle effect" of sodium polysulfides, leading to rapid capacity decay and poor electrochemical performance.

This research seeks to address the challenge by exploring the use of cation and anion-doped MoSe2 electrocatalysts designed to immobilize and catalyze the conversion of sodium polysulfides. The outcomes of this project are crucial for advancing the field of rechargeable battery technology and supporting national interests in sustainable energy storage and environmental protection.

Additionally, the project promotes education and diversity by providing research opportunities and training in advanced battery technologies for undergraduate and graduate students, particularly those from underrepresented groups in STEM fields. The outreach activities, including summer workshops and demonstrations of battery technologies, will help cultivate awareness among the next generation of scientists and engineers regarding critical issues such as global warming and clean energy.

The objective of this project is to elucidate the effects of cation and anion doping on MoSe2 with tuned surface and defect structures as electrocatalysts for sodium polysulfides immobilization and catalytic conversion in room-temperature sodium-sulfur (Na-S) batteries. The research will focus on: (i) computational screening of anion and cation dopants in MoSe2 to identify those that enhance polysulfide adsorption and reversible conversion kinetics; (ii) designing and synthesizing cation/anion doped MoSe2 electrocatalysts for dual adsorption-catalysis functionality; (iii) investigating the impact of doping on the electrochemical performance and elucidating the mechanistic details of Na-S chemistry; and (iv) using reactive molecular dynamics (MD) simulations to elucidate interfacial reaction mechanisms and kinetics.

The project will leverage density functional theory (DFT) and ReaxFF MD simulations along with in situ/ex-situ transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), energy-dispersive X-ray spectroscopy (EDX), and differential electrochemical mass spectroscopy (DEMS) to achieve a fundamental understanding of adsorption, interfacial reaction mechanisms, kinetics, and the structural/compositional evolution of sodium polysulfides at the interfaces. This integrated computational and experimental investigation will provide unprecedented insights into the mechanisms of polysulfide chemistry to enable the development of advanced, long-life Na-S batteries for sustainable energy storage solutions.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.