Molecule Engineering of Sugar Derivatives as Electrolyte Additives for Deep‐Reversible Zn Metal Anode

Abstract The cycling performance of zinc‐ion batteries is greatly affected by dendrite formation and side reactions on zinc anode, particularly in scenarios involving high depth of discharge (DOD) and low negative/positive capacity (N/P) ratios in full cells. Herein, drawing upon principles of host–guest interaction chemistry, we investigate the impact of molecular structure of electrolyte additives, specifically the −COOH and −OH groups, on the zinc negative electrode through molecular design. Our findings reveal that molecules containing these groups exhibit strong adsorption onto zinc anode surfaces and chelate with Zn 2+ , forming a H 2 O‐poor inner Helmholtz plane. This effectively suppresses side reactions and promotes dendrite‐free zinc deposition of exposed (002) facets, enhancing stability and reversibility of an average coulombic efficiency of 99.89 % with the introduction of Lactobionic acid (LA) additive. Under harsh conditions of 92 % DOD, Zn//Zn cells exhibit stable cycling at challenging current densities of 15 mA ⋅ cm −2 . Even at a low N/P ratio of 1.3, Zn//NH 4 V 4 O 10 full cells with LA electrolyte exhibit high‐capacity retention of 73 % after 300 cycles, significantly surpassing that of the blank electrolyte. Moreover, in a conversion type Zn//Br static battery with a high areal capacity (~5 mAh ⋅ cm −2 ), LA electrolyte sustains an improved cycling stability of 700 cycles.