Studying voltage losses during discharge for biphenyl-sodium polysulfide organic redox flow batteries
Studying voltage losses during discharge for biphenyl-sodium polysulfide organic redox flow batteries
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DOI：
10.1016/j.jpowsour.2023.233538
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发表时间：
2023-11
影响因子：
9.2
通讯作者：
Mohammad M. Bahzad;Doug S Aaron;K. D. Kihm;Seung-Hak Shin;Umar Saeed;Yu-Kai Weng
中科院分区：
文献类型：
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作者：
Mohammad M. Bahzad;Doug S Aaron;K. D. Kihm;Seung-Hak Shin;Umar Saeed;Yu-Kai Weng
定量研究了库仑平衡联苯（Bp）|钠-多硫化物（Na2Sx）有机氧化还原液流电池放电过程中的电压损失。采用带原位钠/钠离子参比电极的流动电池，研究了单个半电池的电化学阻抗谱响应。在放电过程中，由Bp/Bp−对组成的阳极约占电池总过电位的58%。进一步的研究表明，在放电过程中，动力学过电位决定了阳极和阴极的电压损失。多硫化钠半电池的EIS响应在高频和低频处呈现两个半圆。由于有关高频半圆与物理过程的文献有限，因此本工作扩展了使用原位和非原位电化学诊断工具对阴极高频EIS特征的研究。相对于复杂的Na2Sx， Bp Nyquist图由单个半圆组成，因为它的氧化还原反应更简单。采用Tafel分析法计算交换电流密度值，Bp的交换电流密度低于Na2Sx。这一发现解释了与Na2Sx相比，相对较高的Bp动力学电压损失。
Voltage losses during discharge have been quantitatively investigated in a coulombically balanced biphenyl (Bp)|sodium-polysulfide (Na2Sx) organic redox flow battery. The individual half-cell electrochemical impedance spectroscopy (EIS) response was studied using a flow cell with an in-situ sodium/sodium-ion reference electrode. The anode, consisting of Bp/Bp−couple, contributed approximately 58% of the total cell overpotential during discharge. Further investigation revealed that kinetic overpotential dominating both anode and cathode voltage losses during discharge. The EIS response for the sodium-polysulfide half-cell exhibits two semicircles at high and low frequencies. Since there is limited literature relating the high-frequency semicircle to a physical process, this work extends the investigation of cathode high-frequency EIS features using in-situ and ex-situ electrochemical diagnostic tools. The Bp Nyquist plot consisted of a single semi-circle due to its simpler redox reaction relative to the more complicated Na2Sx. Tafel analysis was used to calculate exchange current density values, with Bp having a lower exchange current density than Na2Sx. This finding explains the relatively higher Bp kinetic voltage loss as compared to Na2Sx.