Chemical heterogeneity for battery materials

Next-generation rechargeable batteries require materials that offer enhanced electrochemical capabilities. Achieving these goals depends on understanding the fundamental principles governing these materials, which presents challenges associated to the complex interactions between composition, structural characteristics and electrochemical performance in battery materials. Despite intensive research, progress remains limited regarding effective strategies to mitigate the degradation of fragile alkali-metal-deficient frameworks arising from lattice stress and structural or chemo-mechanical instability upon cycling. In this Review, we explore the importance of chemical heterogeneity in rechargeable battery materials. We discuss how heterogeneity at atomic scale, nano-domains and up to phase-segregated levels within particles can enhance the electrochemical properties of battery materials beyond those of their homogeneous counterparts. Introducing chemical heterogeneity, principles and mechanisms can be unlocked to develop materials with improved structural stability, ion conductivity, redox activity, and phase transition characteristics, driving progress in battery technology. Finally, we outline the challenges and strategies for developing the future battery materials.