Achieving energy sustainability requires efforts from not only sourcing clean energy, but also storing and dispatching energy whenever and wherever needed, as well as being energy-efficient whenever possible. Two-dimensional (2D) materials hold great promises as mechanical reinforcement in high strength-to-weight ratio structural materials and as next-generation energy-efficient electronic materials, both of which contribute to less energy consumption with improved performance. Among energy-storage technologies, solid-state batteries (SSB) are particularly attractive due to potentially higher energy density and safer non-flammable solid electrolytes compared with conventional lithium-ion batteries. However, both 2D materials and components of SSB are often exposed to static and dynamic mechanical stresses, posing critical challenges towards their wide applications. The first part of the talk will discuss the mechanical fatigue behavior of 2D materials and their interfaces, reveal their unconventional failure mechanisms, and propose practical strategies to improve their mechanical reliability. The second part will focus on the lithium dendrite issues in SSB and discuss the coupled electro-chemo-mechanical effect in the failure of a garnet solid electrolyte. Through in-situ FIB/SEM experiments, the critical role of stress in regulating the failure of SSB during fast charging is revealed.