分子筛液流电池隔膜的设计制备与传质机理研究

Vanadium redox flow battery (RFB) is an efficient and economic technology for energy storage, while its large-scale implementation remains challenge, which is partially due to the lack of high-performance separator. Current RFB separator is based on polymeric ion-exchange membranes, which is easily swelled in the electrolyte solution and thus leading to low ion selectivity and poor chemical stability. To overcome these bottlenecks of RFB separator, this proposal intends to study design and fabrication of zeolite membrane for RFB separator and its transport mechanism, by utilizing the ordered subnanometer pores and rigid framework of inorganic zeolite to improve the ion selectivity and structural stability of RFB separator. Zeolite framework is designed and zeolite intergranular defect is controlled to precisely create proton transport channels; varying zeolite’s chemical composition and membrane surface functionalization were employed to finely tune the hydrophilicity of zeolite membrane surface to enhance the membrane proton transport rate; exploring new porous electrode supported zeolite membrane to reduce the membrane area resistance, with the aim of developing an array of high-performance zeolite RFB separators; Ion permeation measurements are combined with atomic-level characterization techniques and molecular dynamics simulation to understand the transport and separation mechanism of proton and ion in RFB separator. The implementation of this proposal will provide fundamental and technical insights for development of RFB separator.

全钒液流电池是一种有效且经济的储能技术，但大规模推广应用未尽人意，电池隔膜的技术限制是制约因素之一。现有的隔膜主要是聚合物离子交换膜，其在强酸强氧化性电解质溶液中易发生溶胀，导致离子选择性低、化学稳定性差等瓶颈问题。本项目基于申请者提出的分子筛隔膜技术构思，拟开展分子筛液流电池隔膜的设计制备与传质机理研究。利用分子筛规整的亚纳米孔道和刚性的骨架结构，提升液流电池隔膜的离子选择性和结构稳定性; 通过分子筛的骨架结构设计和分子筛膜晶间缺陷控制，精密构筑质子传输通道；基于对分子筛的化学组成调控和膜表面官能化改性，有序调控表面亲疏水性，提高膜的质子传输速率; 研制新型多孔电极支撑分子筛膜，降低膜面电阻，发展高性能分子筛液流电池隔膜；将离子渗透实验与原子尺度表征技术及分子模拟计算结合，研究质子和离子在分子筛液流电池隔膜中的传质与分离机理。本项目实施将为分子筛液流电池隔膜的发展提供理论指导和技术基础。

全钒液流电池是一种有效且经济的储能技术，但大规模推广应用未尽人意，电池隔膜的技术限制是制约因素之一。基于此，申请人开展了分子筛液流电池隔膜的设计制备与传质机理研究，利用分子筛规整的亚纳米孔道和刚性的骨架结构，提升液流电池隔膜的离子选择性和离子电导率，并研制了新型多孔电极支撑分子筛膜，以降低膜面电阻发展高性能分子筛液流电池隔膜。.本项目通过调整合成液组成对分子筛骨架中硅铝比进行了优化，在不影响孔道结构的情况下提高沸石膜的亲水性，助力质子的快速传输。通过调控晶种层参数、改变合成液组成及合成条件，采用二次生长法在多孔氧化铝陶瓷支撑体上实现了ZSM-5晶体膜的可控制备。通过浸泡实验验证了ZSM-5沸石膜在全钒液流电池苛刻的环境中的膜结构稳定性，结果发现浸泡后的沸石膜的特征峰并未发生偏移或消失，证明所制备的ZSM-5分子筛膜具有十分优异的耐酸性和抗氧化性能。同时，将其应用于全钒液流电池，实现了超低的钒离子渗透速率(0.07 mmol L-1 h-1)。通过自制电池组件评价ZSM-5分子筛膜的电池性能，获得了优异的库伦效率（98%，60 mA cm-2）。此外，由于传统多孔氧化铝陶瓷在单电池中内阻较大，为了进一步降低晶体膜的内阻，扩展晶体膜在液流电池中的应用，项目实施过程申请人首次提出了电极支撑液流电池隔膜技术。通过大数据筛选，选用氮化钛作为电极材料设计并制备多孔氮化钛导电陶瓷支撑体。采用二次生长法成功在电极表面制备出ZSM-5沸石膜，隔膜的面电阻也显著降低(9.64×10-3 Ω cm-2)，优于Nafion 212膜(2.91×10-2 Ω cm-2)。显著降低的面电阻可以有效降低电池内部的极化，推动晶体膜在液流电池中的进一步应用。