Pioneering new paths in sodium-ion batteries: A comprehensive review towards binder-free anode and cathode materials for next-generation energy storage

Significant technological advancements have improved the efficiency and reduced the cost of lithium-ion batteries (LIBs), making them a leading energy storage solution. Despite their high power and energy density, concerns over lithium resource availability, cost, and the need for higher energy density have driven the search for “beyond Li-ion” technologies. Sodium-ion batteries (SIBs) have emerged as a promising alternative due to their similar working principles and manufacturing processes to LIBs. A major component in conventional battery electrodes is the binder, used to hold active materials and conductive additives together. However, binders are often electrochemically inactive, insulating, and mechanically unstable, which can hinder performance by reducing conductivity, causing uneven material distribution, and limiting cycle stability. In contrast, binder-free electrodes offer several advantages, such as higher surface area, better adhesion to current collector, and improved tolerance to volume changes during cycling. These features contribute to enhanced electronic conductivity, improved electrochemical reversibility, and better overall battery performance. This review highlights recent advancements in binder-free anode and cathode materials-including metals, carbon-based structures, MXene, and hybrids-along with novel synthesis strategies. The discussion also covers their impact on rate capability and cycle life, and outlines the current challenges and future directions for realizing practical applications of SIBs. In addition, this review provides an integrative perspective by covering diverse material platform and latest fabrication methods, offering a timely road map for the advancement of the binder-free sodium ion battery technologies.