Application of carbon materials for Zn anode protection in aqueous Zn metal batteries

Aqueous Zn metal batteries (AZMBs) have gained widespread attention due to their high theoretica specific capacity,good safety,and low cost.Unfortunately Zn anodes suffer from serious problems of dendrites and side reactions,which should be solved by modifying the Zn anode (Zn host,protective layer),electrolyte,and separator.Carbon materials with structurally tunable and physicochemical stability properties have been widely used in the study of Zn anode protection and have also been reviewed in the past years.Nevertheless,review reports on carbon-based Zn anodes for Zn anode protection from new perspectives are still urgently needed.Moreover,the timeliness of the review reports is very valuable for researchers to timely and accurately understand the dynamics of the research field.Herein,this review firs reports the significance of AZMBs and summarizes the current main challenges that should be solved for practical application.Then,the ways to construct long-life Zn anodes using carbon materials from the perspectives of modified carbon materials with gradient properties (gradient zincophilicity,gradient electrical conductivity,and multigradient deposition) as protective layers/hosts to guide Zn ions toward bottom-up gradient Zn deposition are highlighted.In addition,the recent advances of carbon materials for electrolyte and separator modifications are demonstrated.Finally,the remaining challenges and future perspectives of carbon materials in AZMBs Zn anode protection are briefly outlined.