Scalable hard carbon production for sodium-ion batteries: Integrated precursor selection, thermochemical conversion, and tandem processing

Sodium-ion battery has been widely regarded as a cost effective and scalable solution for short/medium-term energy storage, where hard carbon anode serves as a crucial role in determining the energy density and charging rate of full-cell device. To date, most studies have focused on the synthesis strategies and performance of hard carbons at laboratory scale, while few reports address the industrial production processes from the perspective of thermochemical transformation and carbon structure evolution. Herein, we evaluate research and development strategies of hard carbons from the viewpoint of processing operation and industrial production, mainly including precursor selection, pretreatment, carbonization, and post treatment. Notably, thermochemical transformation and engineering are highlighted as a key part to tailor carbon skeleton for Na-ion storage. Finally, challenges in large-scale production and future research directions are outlined for hard carbon enhancement and Na-ion full-cell development.