Phosphorene, mono- or few-layer-thick form of black phosphorus (BP), exhibits a puckered honeycomb structure, in which each phosphorus atom binds with three neighboring atoms. It has emerged as a promising candidate for electrochemical applications due to its large surface area and highly desirable electrical properties. However, BP flakes are reported to chemically degrade rapidly upon exposure to ambient conditions, which greatly hinders its potential applications. This chapter first lays out the structural degradation problems of BP and then summarizes up-to-date strategies for BP protection. After overviewing these challenges and protection methods, the promising applications of BP in energy storage and oxygen production are reviewed.