Repairing and regenerating the unbalanced electrolytes is critical for the long-term operation of vanadium redox flow batteries (VRFBs). In this work, we propose a simple strategy to repair the unbalanced electrolytes for capacity recovery through chemical oxidation with the V(V) electrolyte and develop a method based on image analysis to obtain the electrolytes’ V(IV) ion contents. When the V(V) electrolyte with the same concentration as that of the unbalanced electrolyte is added to the unbalanced electrolyte, V(V) ions gradually oxidize V(III) ions to V(IV) ions, and the color of the electrolyte changes significantly. By extracting the RGB information of the electrolyte image, it is found that the B channel value presents the highest sensitivity to the V(IV) ion content. Thus, the relationship between them is fitted, and the R 2 of the fitted curve reaches 0.9978. Furthermore, the image analysis-based method is applied to predict the V(V) electrolyte volumes needed to repair the unbalanced electrolytes. Results show that the deviation of the B channel values between the recovered and standard V(IV) electrolytes is within 5%, demonstrating the effectiveness of the proposed repair strategy and image analysis-based method, which show great promise for practical VRFB applications.
Shirui Li,Kuikui Xiao,Xi Liu,Jiangdong Sun,Dong Cai,Shuo Yang,Yinhang Zhang,Huagui Nie,Zhi Yang
Cathode prelithium agent is regarded as the most applicable approach to compensate the initial capacity loss in lithium ion batteries (LIBs). Li 2 NiO 2 (LNO) has attracted numerous attention due to its superior environmental stability and reliable synthesis approach. To promote the commercial application of LNO, the understanding of the degradation mechanism induced by air-exposure and finding reliable strategies to improve the air stability are necessary. Herein, by preserving the LNO in different environments (relative humidity of 70 % and 40 %), the surface chemistry evolution of LNO is subtly investigated, which shows Li 2 CO 3 and LiOH cover the surface of the LNO, which decline the Li + diffusion kinetics as well as the charge capacity. What′s more, the slurry turns gel when the LNO exposed to the environment of 70 % relative humidity for 2 days and 40 % relative humidity for 5 days. Facile approaches, including washing the deteriorative LNO with ethanol, reacting the alkali components with H 3 BO 3 , and coating the LNO with Al 2 O 3 are conducted to recover the disabled LNO, which retains 84.2 % of initial capacity. In addition, a coating approach is proposed for the fresh LNO to effectively improve the air stability. This work provides guideline to the commercial application of the LNO. Graphical This work investigates the chemical evolution of LNO under varying conditions of relative humidity and exposure time. Since LNO will fail after two days of exposure to the environment with 70 % relative humidity, strategies to recover the failed LNO and improve the fresh LNO are proposed.
危险品化学品经营许可证（带存储）