Around four billion discarded tires are in landfills annually, highlighting the need for sustainable recycling methods. One solution is to transform waste tires into carbon powder as active anode material for alkali-ion battery. However, heavy metals and other contaminants in tires reduce the electrochemical performance of the resulting carbon material. Traditional approaches often employ concentrated sulfuric and hydrofluoric acids for purification. However, these methods present safety risks and environmental concerns, particularly when it comes to scale up for commercial production. This study explores a green alternative method through hydrothermal treatment, which effectively leaches contaminants to produce a carbon precursor suitable for anodes without harsh chemicals. Advanced collaborative analyses shed light on the mechanisms within the hydrothermal process and reveal the material properties that enhance electrochemical performance.