Nanocomposites Based on 2D Materials: Synthesis–Property Relationships for Next‐Generation Energy Storage: A Critical Review

ABSTRACT This review delivers an advanced, critical assessment of the electrochemical functionality of state‐of‐the‐art two‐dimensional (2D) material nanocomposites including graphene, MoS 2 , MXenes, WS 2 , and phosphorene for next‐generation energy storage systems, with a rigorous focus on the mechanistic role of synthesis methodology in dictating structure property relationships. We elucidate how specific synthesis strategies govern the structural and electrochemical behavior of different 2D materials. For instance, hydrothermal synthesis promotes uniform nanostructuring and enhanced ion diffusion in MoS 2 ‐based composites, while chemical vapor deposition (CVD) enables defect‐controlled, high‐conductivity graphene architectures. Microwave‐assisted synthesis facilitates rapid nucleation and reduced processing time, leading to improved crystallinity and electrochemical kinetics. In MXenes, etching and post‐treatment processes critically determine surface terminations (–O, –OH, –F), which directly influence electrical conductivity and ion transport properties. These synthesis‐dependent structural modifications including defect density, interlayer spacing, and heterointerface formation play a decisive role in determining specific capacity, rate capability, and cycling stability. Unlike conventional reviews, this work integrates synthesis–structure–performance relationships with practical scalability and environmental considerations, providing a critical and application‐oriented framework for the rational design of next‐generation energy storage materials.