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Aqueous zinc-ion batteries (AZIBs) show enormous potential as a large-scale energy storage technique. However, the growth of Zn dendrites and serious side reactions occurring at the Zn anode hinder the practical application of AZIBs. For the first time, we reported a fluorine-containing surfactant, i.e., potassium perfluoro-1-butanesulfonate (PPFBS), as an additive to the 2 M ZnSO4 electrolyte. Benefitting from its hydrophilic sulfonate anion and hydrophobic long fluorocarbon chain, PPFBS can promote the uniform distribution of Zn2+ flux at the anode/electrolyte interface, allowing the Zn/Zn cell to cycle for 2200 h. Furthermore, PPFBS could inhibit side reactions due to the existence of the perfluorobutyl sulfonate (C4F9SO3−) adsorption layer and the presence of C4F9SO3− in the solvation structure of Zn2+. The former can reduce the amount of H2O molecules and SO42− in contact with the Zn anode and C4F9SO3− entering the Zn2+-solvation structure by replacing SO42−. The Zn/Cu cell exhibits a superior average CE of 99.47% over 500 cycles. When coupled with the V2O5 cathode, the full cell shows impressive cycle stability. This work provides a simple, effective, and economical solution to the common issues of the Zn anode. [ABSTRACT FROM AUTHOR]

• Two transition metal borates are proposed as new promising anode materials for NIBs. • The conversion reaction can be thoroughly realized for transition metal borates. • Na insertion into transition metal borates are energetically more favorable than oxides. • Fe 3 BO 5 /Na 2 V 3 (PO 4) 2 F 3 full cell exhibits a high energy density of 180.3 Whkg−1. Development of anode materials with high performance is crucial for the successful application of Na-ion batteries. In this study, we provide a novel type of conversion-type anode materials, transition metal borates, as promising candidates for Na-ion storage. The transition metal borates (Fe 3 BO 5 and Ni 3 (BO 3) 2) are successfully fabricated by a facile sol-gel route. When they are firstly evaluated for Na-ion storage, they deliver remarkably better Na-ion insertion kinetics and high reversible capacity than transition metal oxides. It's notable that the conversion reaction can be thoroughly realized for transition metal borates during sodiation/desodiation process accompanying with the change of B-O coordination. First-principles calculation indicates that Na insertion into transition metal borate are energetically much more favorable compared with transition metal oxides. Furthermore, carbon coated borates are designed and firstly prepared, which exhibit good rate capability and excellent cycling stability. Moreover, the Fe 3 BO 5 /Na 2 V 3 (PO 4) 2 F 3 full cell exhibits a high energy density of 180.3 Wh kg−1 at a high power density of 150.1 W kg−1. This study demonstrates a class of new promising conversion-type anodes and also verifies the practical application in Na-ion batteries with high energy/power density. [ABSTRACT FROM AUTHOR]