Imagine if solid state materials could be designed over multiple length scales and created with precise control over their various forms of complexity. An integrated approach is being used to efficiently combines theory, synthesis, and operando characterization to control, assemble, and stabilize solid state materials and with various forms of complexity for enhancement of ion and/or electron transport. While computational materials design is a well-established with many known successes in the field of Li-ion chemistry, compounds are usually not designed with defects in mind or an understanding of what synthetic pathway can be utilized to achieve them. By understanding how materials complexity influences electrochemical performance, we are advancing comprehensive rational materials design beyond the level of defect-free design. Furthermore, the science of synthesis needs to consider extrinsically controlled complexity. A large-scale effort has been established which combines extensive and state of the art in situ and ex situ characterization tools. This talk will provide an overview of the results and approaches being taken as they relate to energy storage and conversion applications.