Improved Graphene-Based Sodium-Ion Battery Anodes Using Low Surface Area and Tempreture

Abstract

Reduced graphene oxide (rGO) has emerged as a strong candidate for high-capacity anodes in sodium-ion batteries, yet its inherently large specific surface area—mainly caused by structural exfoliation during reduction promotes excessive solid–electrolyte interphase (SEI) growth, resulting in substantial irreversible capacity during early cycles. To address this drawback, we developed a strategy to produce rGO powders with controlled, low surface area by combining spray drying with gradual thermal reduction, thereby suppressing over-exfoliation. Electrodes fabricated from these powders and reduced at different temperatures (200–1000 °C) were systematically compared with high-surface-area counterparts to disentangle the contributions of oxygen functionality and surface area to electrochemical behavior. The optimized sample reduced at 400 °C delivered the most favorable performance, achieving a reversible capacity of 216 m Ah g⁻¹ at 100 mA g⁻¹ and maintaining 85% of its capacity after 200 charge–discharge cycles. Furthermore, irreversible capacity loss was diminished by a factor of two to three relative to earlier reports. Although further refinement is needed to achieve full commercial viability, these findings underscore the importance of morphological control strategies that minimize surface area, promote structural restacking, and optimize oxygen functional group content to enhance the long-term performance of rGO-based sodium-ion battery anodes.