Membranes in non-aqueous redox flow battery: A review

Yuan, Jiashu; Pan, Zheng‐Ze; Jin, Yun; Qiu, Qianyuan; Zhang, Cuijuan; Zhao, Yicheng; Li, Yongdan

doi:10.1016/j.jpowsour.2021.229983

Cited by 95 publications

(95 citation statements)

References 118 publications

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“…Membranes have been evaluated and developed for use in the more mature aqueous RFBs, including commercial systems, 13−15 but few studies have considered membranes for use in nonaqueous RFBs. 10,16 Battery separator membranes can be porous or nonporous in nature. Many aqueous flow battery systems use nonporous ionexchange membrane (IEM) separators 17 that are similar to the membranes used in fuel cells.…”

Section: ■ Introductionmentioning

confidence: 99%

“…22−24 The pore dimensions in these commercially available separators are very large relative to the size of the molecules, so they promote high conductivity but also result in higher active material permeability or cross-over. 16,17 The transport mechanism is different for porous and nonporous membrane separators. 25,26 In nonporous IEMs, transport is often described by the solution-diffusion model where the penetrant molecule first dissolves in the polymer matrix and subsequently diffuses through the solvated membrane before desorbing at the downstream side.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermodynamic Interactions as a Descriptor of Cross-Over in Nonaqueous Redox Flow Battery Membranes

McCormack

Koenig

Geise

2021

ACS Appl. Mater. Interfaces

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Grid-scale energy storage is increasingly needed as wind, solar, and other intermittent renewable energy sources become more prevalent. Redox flow batteries (RFBs) are well suited to this application because of the advantages in scalability and modularity over competing technologies. Commercial aqueous flow batteries often have low energy density, but nonaqueous RFBs can offer higher energy density. Nonaqueous RFBs have not been studied as extensively as aqueous RFBs, and the use of organic solvents and organic active materials in nonaqueous RFBs presents unique membrane separator challenges compared to aqueous systems. Specifically, organic active material cross-over, which degrades battery performance, may be affected by membrane/active material thermodynamic interactions in a fundamentally different way than ionic active material cross-over in aqueous RFB membranes. Hansen solubility parameters (HSPs) were used to quantify these interactions and explain differences in organic active material permeability properties. Probe molecules with a more unfavorable HSP-determined enthalpy of mixing with the membrane polymer exhibited lower permeability or cross-over properties. The HSP approach, which accounts for the uncharged polymer backbone and the charged side chain, revealed that interactions between the uncharged organic probe molecule and the hydrophobic polymer backbone were more important for determining permeability or cross-over properties than interactions between the probe molecule and the hydrophilic side chain. This result is significant for nonaqueous RFBs because it suggests a decoupling of ionic conduction expected to predominantly occur in charged polymer regions and cross-over of organic molecules via hydrophobic or uncharged polymer regions. Such decoupling is not expected in aqueous systems where active materials are often polar or ionic and both cross-over and conduction occur predominantly in charged polymer regions. For nonaqueous RFBs, or other membrane applications where selective organic molecule transport is important, HSP analysis can guide the co-design of the polymer separator materials and soluble organic molecules.

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Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Thermodynamic Interactions as a Descriptor of Cross-Over in Nonaqueous Redox Flow Battery Membranes

McCormack

Koenig

Geise

2021

ACS Appl. Mater. Interfaces

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“…Despite recent efforts by researchers to develop NA-RFBs, one of the great challenges is to develop membranes that meet all the requirements for their proper functioning, which include several properties such as high ionic conductivity and selectivity, low swellability, low cost, and high stability, both mechanical and chemical [209][210][211]. To this end, Yuan et al in 2021 presented a set of radar plots summarizing the performance, advantages, and shortcomings of current membranes [63]. The analysis of the plots in Figure 7 allows us to observe why none of the current advances in membrane development are solving the problems of the technology.…”

Section: Non-aqueous Solventsmentioning

confidence: 99%

Redox Flow Batteries: Materials, Design and Prospects

et al. 2021

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The implementation of renewable energy sources is rapidly growing in the electrical sector. This is a major step for civilization since it will reduce the carbon footprint and ensure a sustainable future. Nevertheless, these sources of energy are far from perfect and require complementary technologies to ensure dispatchable energy and this requires storage. In the last few decades, redox flow batteries (RFB) have been revealed to be an interesting alternative for this application, mainly due to their versatility and scalability. This technology has been the focus of intense research and great advances in the last decade. This review aims to summarize the most relevant advances achieved in the last few years, i.e., from 2015 until the middle of 2021. A synopsis of the different types of RFB technology will be conducted. Particular attention will be given to vanadium redox flow batteries (VRFB), the most mature RFB technology, but also to the emerging most promising chemistries. An in-depth review will be performed regarding the main innovations, materials, and designs. The main drawbacks and future perspectives for this technology will also be addressed.

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“…An emerging class of RFBs is those utilizing nonaqueous chemistries, as their electrolytes offer extended electrochemical stability windows and the possibility of using redox couples that are infeasible in aqueous electrolytes due to their stability, solubility, or redox potential. Consequently, nonaqueous redox flow batteries (NAqRFBs) may enable lower system costs through increased energy density, unlocking new routes toward economically viable RFB systems. − Despite this intriguing possibility, current NAqRFB prototypes display limited performance and lifetime due, at least in part, to the lack of membranes with suitable combinations of selectivity, conductivity, and stability. − …”

Section: Introductionmentioning

confidence: 99%

“…Ideally, a RFB membrane should simultaneously block the undesired transport of redox-active species and solvent between the positive and negative electrolytes, promote the rapid and selective transport of supporting ions, possess high mechanical and chemical stability, and be conducive to low-cost and scalable production . Implementing these properties in practice is more challenging, and while there have been considerable efforts dedicated to advancing redox chemistries for NAqRFBs, fewer attempts have focused on developing membranes to support leading chemistries, frustrating full cell performance and durability. − Most prior research on NAqRFBs incorporates commercially available ion-exchange membranes, , which are not specifically engineered for nonaqueous electrochemical environments and thus typically display unfavorable combinations of ionic conductivity and species selectivity. − Therefore, new separation approaches must be considered, with particular emphasis on materials developed for energy storage technologies that operate in similar (electro)chemical environments. To this end, the extensive body of knowledge generated from the research and development of separators and membranes for Li-ion batteries may inform NAqRFB systems .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Lithium-Conducting Composite Polymer–Ceramic Membranes for Use in Nonaqueous Redox Flow Batteries

Gandomi

Krasnikova

Akhmetov

et al. 2021

ACS Appl. Mater. Interfaces

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Redox flow batteries (RFBs) are a burgeoning electrochemical platform for long-duration energy storage, but present embodiments are too expensive for broad adoption. Nonaqueous redox flow batteries (NAqRFBs) seek to reduce system costs by leveraging the large electrochemical stability window of organic solvents (> 3 V) to operate at high cell voltages and to facilitate the use of redox couples that are incompatible with aqueous electrolytes. However, a key challenge for emerging nonaqueous chemistries is the lack of membranes/separators with suitable combinations of selectivity, conductivity, and stability. Single-ion conducting ceramics, integrated with polymeric fillers to make flexible composites, may offer a pathway to the performance attributes needed for competitive nonaqueous systems. Here, we explore composite polymer-inorganic binder-filler membranes for lithium-based NAqRFBs, investigating two different ceramic compounds with NASICON-type (NASICON: sodium (Na) Super Ionic CONductor) crystal structure, Li1.3Al0.3Ti1.7(PO4)3 (LATP) and Li1.4Al0.4Ge0.2Ti1.4(PO4)3 (LAGTP), blended with a polyvinylidene fluoride (PVDF) polymeric matrix. We characterize the physicochemical and electrochemical properties of the synthesized membranes as a function of processing conditions and formulation using a range of microscopic, spectroscopic, and electrochemical techniques. We then integrate select composite membranes into a single electrolyte flow cell configuration and perform polarization measurements with different redox electrolyte compositions. We find that mechanically robust, chemically stable LATP/PVDF composites can support > 40 mA cm −2 at 400 mV cell overpotential, but further improvements are needed in selectivity. The insights gained through this work begin to establish the foundational knowledge needed to advance composite polymer-inorganic membranes/separators for NAqRFBs.

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Membranes in non-aqueous redox flow battery: A review

Cited by 95 publications

References 118 publications

Thermodynamic Interactions as a Descriptor of Cross-Over in Nonaqueous Redox Flow Battery Membranes

Thermodynamic Interactions as a Descriptor of Cross-Over in Nonaqueous Redox Flow Battery Membranes

Redox Flow Batteries: Materials, Design and Prospects

Synthesis and Characterization of Lithium-Conducting Composite Polymer–Ceramic Membranes for Use in Nonaqueous Redox Flow Batteries

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