大连化物所-李先锋&谢聪鑫 Angew | 溴辅助MnO2溶解化学实现能量密度超过300 Wh L−1的混合液流电池

近日，中国科学院大连化学物理研究所-李先锋&谢聪鑫等人在Angew上发表重要文章，论文题为“Bromine Assisted MnO2 Dissolution Chemistry: Toward a Hybrid Flow Battery with Energy Density of over 300 Wh L^-1”。Mn²⁺/Mn³⁺氧化还原对由于具有高氧化还原电位、溶解度和优异的动力学特性，被认为是一种很有前途的高能量密度电池正极。然而，Mn³⁺的歧化副反应导致“死”MnO2的积累，限制了其可逆性和进一步的能量密度。在此基础上，作者提出了一种新型的Mn²⁺和Br^-的混合正极材料，用于高能量密度和长循环寿命的流动电池。在设计中，通过化学-电化学反应，“死”MnO2可以通过Br^-完全排出。以Cd/Cd²⁺为负极，组装的溴锰流电池(BMFB)在80 mA cm^-2和360 Wh L^-1的能量密度下，具有76%的高能量效率。以硅钨酸为负极的电池可在80 mA cm^-2的温度下连续运行2000次以上。BMFB具有高功率密度、能量密度和耐用性，显示出大规模储能的巨大潜力。

第一作者：Yun Liu

通讯作者：Congxin Xie, Xianfeng Li

通讯单位：中国科学院大连化学物理研究所

论文DOI：10.1002/anie.202213751

Figure 1.    The  principle  and  electrochemical  detection  of  the BMFB.  a)  Schematic  diagram  of  the  assembled  battery  with  Cd2+/Cd  as  anode  during  the  charge-discharge process.  b) Cyclic voltammetry (CV) of  50 mM  MnSO4+2 M  H2SO4electrolyte at  the  sweep rate of10 mV s-1within 1.5-2.2 V (Illustration is  a  partial enlargement). c) CV of 50 mM MnSO4+50 mM HBr+2 M H2SO4electrolyte at 10 mV s-1within the potential range of 1.2-2.2 V. d) CV of 50 mM HBr electrolyte at 10 mV s-1at 1.3-1.75 V. e) Summary of the electrochemical mechanism of MnSO4+HBr. All electrochemical tests were performed using carbon felt as working electrode and cadmium sheets as reference and counter electrode.   

Figure 2. The Raman detection of chemistry between Br-and MnO2and In-situRaman detection of the charge-discharge process of CBMFB. (a)Chemical reactions of Br-and MnO2in different electrolytes (Insets are photos of different electrolytes). (b) In-situ Raman (100~700 cm-1) test of the charge-discharge process of a battery assembled with Cd2+/Cd as anode. Battery was charged and discharged at constant current of 10 mA. Raman recorded signals every 100 seconds.

Figure 3. The performance of the battery.(a)The charge–discharge profiles of 1 M MnSO4 +2 M H2SO4+0.5 M CdSO4and 1 M MnSO4+1 M HBr+2 M H2SO4+0.5 M CdSO4electrolytesat 80 mA cm-2with thevoltagecut-off of 2.3 V and 0.1V. (b) The behavior of the battery  assembled with 1 M HBr at the current density range from 40–120 mA cm-2. The long term cycling performance of the 1 M  (c) 、2 M  (e) and 3 M (g) electrolyte, respectively. The charge–discharge profiles of 2 M (d) and 3M (f) electrolyte at 80 mA cm-2. (h) The cycling performance of the battery assembled with 0.3 M H4SiW12O40+0.5 M MnSO4+0.5 M HBr+1.5 M H2SO4 as electrolyteat 80 mA cm-2.

Figure 4. SEM images of positive electrode. a-c)Surface morphology of positive electrode after charging assembled with HBr-containing electrolyte. d-f) Electrode morphology detection assembled with electrolytecontaining HBr after 350 cycles.  g-i) Electrode surface morphology after 25 cycles of batteryassembly without HBr in electrolyte.

Figure 5.  Comparison of energy densities of different aqueous battery systems. All battery systems are summarized based on actual tested concentrations and battery open circuit voltage data. The energy density data are based on the one-sided volume of electrolyte. All the abbreviations of batteries and related references are shown inthe supplementary information.

【总结】

总之，通过调整正极化学，作者演示了一种高能量密度的锰基流动电池，其中“死”MnO2的积累可以通过MnO2和HBr之间的化学反应被激活。结果表明，以Cd/Cd²⁺为负极的流动电池具有360W h L^-1的超高能量密度，远远高于大多数已报道的水系电池。此外，组装的CBMFB在电流密度为80 mA cm^-2时，具有高达76%的高EE，并能保持500多次循环，表现出高功率密度和长循环寿命。由于镉的不规则体积沉积是限制电池循环稳定性的主要问题，以硅钨酸为负极的电池可以在80 mA cm^-2的温度下连续运行2000多次，进一步证实了正极液的可靠性和通用性。结合高功率、能量密度和超强稳定性，CBMFB具有大规模储能的巨大潜力。

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球差电镜 | 有限元模拟 | 理论计算

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