Iron-Loaded Carbon Spherogels as Sustainable Electrode Materials for High-Performance Lithium-Ion Batteries

The increasing demand for sustainable energy storage drives the development of advanced lithium-ion battery (LIB) materials that combine high performance, cost efficiency, and environmental sustainability. Carbon spherogels, characterized by high surface area, interconnected porosity, and high conductivity, are promising electrode candidates; however, they suffer from low specific capacities when used alone. This study presents iron-loaded carbon spherogels as next-generation LIB electrodes, leveraging iron's high theoretical capacity, abundance, and eco-friendliness. A scalable and tailorable synthesis method enabled the integration of tunable iron contents (15-40 mass %) into the carbon framework, forming robust porous networks with uniformly distributed iron nanoparticles. Electrochemical characterization revealed high specific capacities (up to 1190 mAh g^-1) and high cycling stability (>99% Coulombic efficiency over 300 cycles). Post-mortem analysis highlighted the synergistic interaction between iron redox activity and carbon matrix stability. The medium (27 mass %) iron-loaded carbon spherogel sample achieved the best balance between capacity and durability. These findings position iron-loaded carbon spherogels as sustainable, high-performance LIB electrodes, offering a cobalt-free and nickel-free alternative that addresses key challenges of conversion-type materials, such as volume expansion and capacity fading.