Lithium carboxylate: Effectively suppressing hydrogen evolution by self-introducing CO2 in aqueous electrolyte

We have found that the formation of passivation film plays a major role in the negative shift of the decomposition voltage in the hydrogen-generating process. Both the hydrolysis of weak acid ions and the decarboxylation reaction of carboxylate can make the LiCO 2 CH 3 produce a passivation film to inhibit the water decomposition to a certain extent. As for the LiCO 2 CF 3 without hydrolysis of weak acid ion, it can be highly possible to facilitate the introduction of CO 2 via its carboxylate specific decarboxylation reaction, and further produce lithium carbonate passivation film as well. However, the water decomposition voltage in the oxygen-producing process is more dependent on the properties of lithium salt anions. Those with strong electron-absorbing groups such as the trifluoromethyl are more likely to effectively endue the aqueous electrolyte with a high oxidative decomposition potential . Moreover, the concentration of LiCO 2 CF 3 aqueous electrolyte can reach up to 28 mol kg −1 , and hence the electrochemical stability window of this water-base electrolyte can be expanded to about 3.0 V. This work provides a new idea for the selection of high concentration lithium salt.