A review on zinc electrodes in alkaline electrolyte: Current challenges and optimization strategies

•The problems of uneven Zn deposition, hydrogen evolution, surface passivation in Zn electrodes of AZBs are summarized.•The mechanisms of these problems and their impacts on the performances of AZBs are analyzed.•The major strategies in terms of anode, interface and electrolyte to address these problems are discussed.•The development directions and focused issues of Zn electrodes of AZBs in the future are presented.