液流电池理论与技术——PVDF质子传导膜的研究与应用

PVDF proton conductive membranes for vanadium redox flow batteries

全钒液流电池（VRFB）是一种大规模蓄电储能设备,在可再生能源利用和节能技术领域将发挥重要作用,该过程所需的质子传导膜要具备优良的导电性、阻钒性、稳定性以及合理的成本.该研究突破以往离子交换膜的概念限制,提出利用纳米尺度孔径膜材料的“筛分”效应,满足全钒液流电池对隔膜综合性能的需求.首次提出分子间亲水/疏水相互作用诱导高分子溶液相分离的成膜原理,通过在疏水性高分子溶液中引入亲水性单体聚合形成的低聚物方式,调控铸膜液中分子间相互作用和相分离过程动力学,制备纳米尺度的高稳定性多孔膜.在大量科学研究工作基础上,完成工业规模的制膜工艺放大和批量化生产,所制聚偏氟乙烯（PVDF）质子传导膜面积为800 mm＆#215;900 mm,厚度在60～150μm之间可调,电导率达到3＆#215;10-2 S/cm.利用自制膜装配成8 kW的电堆,其能量效率达到72％,基本满足全钒液流电池产业化发展需求.

Vanadium redox flow batteries （VRFB） are regarded as one of the most promising technologies for massive electrical energy storage for renewable energy and energy-saving processes. Such devices have the merits of long lifespan, simple configuration and independent power and capacity ratings and have abstracted significant attention in recent years. Proton conducting membrane one of the key components in VRFB systems, plays the role of conducting protons during charge/ discharge cycles, and prevents vanadium ions from direct contact between the positive and negative half-cell electrolytes. To achieve high energy efficiency, long life and low cost of a VRFB stack, the membrane should meet the requirements of high conductivity, chemical and mechanical resistance, low permeability of vanadium ions and affordable cost. We introduce polymeric hydrophilic/hydrophobic interactions into membrane formation, and propose a general and straightforward strategy for preparing membranes with nanometer-scale pores. Poly（vinylidene fluoride） （PVDF） and sodium allyl sulfonate （SAS） are used respectively as the membrane material and pore-generator, which offer chemically stable and oxidation-resistant membranes with various potential applications. We have been able to scale up the manufacture process to produce membranes of area of 800x900mm, thickness of 60-150 gm and conductivity around 3x10 2 S/cm. VRFB stacks with the membranes have been shown to have an energy efficiency about 72% for a 8 kW system.