Realizing chemical adsorption mechanism for stabilizing zinc anode instead of physical adsorption by adding...

Dendritic growth, hydrogen evolution reaction, and passivation of zinc anode severely limit the practical use of zinc metal batteries. Developing acidic electrolyte additives is capable of markedly augmenting the stability of zinc anode. However, the adsorption type of acidic additives on zinc anode is still unclear and its mechanism of stabilizing zinc anode needs to be further studied. In this work, the adsorption types of three dicarboxylic acids on zinc anode and action mechanism of stabilizing zinc anode are investigated in depth. The results show that the adsorption type of dicarboxylic acid on zinc anode is chemical adsorption instead of physical adsorption. The dicarboxylic acid reacts with the zinc anode to produce corresponding dicarboxylate and H₂. The dicarboxylate significantly inhibits the side reactions occurring at the zinc anode. As the number of -OH groups on the dicarboxylic acid backbone increases, the faster the chemical adsorption rate, the better the inhibition of side reactions. However, the loss of zinc anode is also more serious. In addition, the relationship between the SEI structure of Zn anode and the chemical adsorption of organic acids is explored. Compared with malic acid and tartaric acid additives, succinic acid additive has the best effect in stabilizing Zn anode. Zn||Cu asymmetric battery can be stably cycled for upwards of 2, 760 h at 4 mA/cm² and 4 mAh/cm². This work provides valuable guidance for elucidating the action mechanism of stabilizing zinc anode with acidic electrolyte additives.