Toray Creates Membrane Separators to Recover Lithium from Used Lithium-Ion Batteries
- A new highly lithium-selective nanofiltration membrane vastly improves acid resistance -

Aug. 29, 2022

                                   
Toray Industries, Inc.
Global Environment Research Laboratory

Tokyo, Japan, August 29, 2022 – Toray Industries, Inc. announced today that it has innovated a nanofiltration membrane to recover lithium from used automotive lithium-ion batteries which are expected to be generated in large quantities in the future and are currently largely disposed of. Toray is already starting to evaluate the recovery using actual lithium-ion batteries and will accelerate research and technological development to commercialize its approach.

Demand for lithium resources should surge with electric vehicle uptake. The challenge with the mainstream evaporation pond process (see glossary note 1) for lithium production is that the number of high-output locations is limited. The alternative to this is the ore process (see glossary note 2) which has issues with its lengthy production process and high-temperature heat treatment, generating high carbon dioxide emissions and increased costs which could drive lithium-ion battery prices even higher.

Nanofiltration membranes can selectively separate dissolved multivalent ions and organic matter. Prime uses of these membranes are to filter ground and river water hardness and agricultural chemicals. They also desalinate and purify in food and biotechnology applications. One downside of conventional nanofiltration membranes is their vulnerability to highly acidic solutions, limiting their application to the neutral region. Another is insufficient selectivity for multivalent ions, hampering separation efficiency. Prevailing membranes thus cannot use potent acids to leach and recover valuable metals from used lithium-ion batteries.

Toray created a cross-linked polymer membrane combining a highly acid-resistant setup and a precision pore structure smaller than 1 nanometer. This success is the result of using organic synthesis, polymer chemistry, and nanotechnology after analyzing membrane degradation from acids and optimal membrane pore structures for selective separation. The acid-resistance of this membrane is around five-fold higher than conventional offerings, with the selectivity being 50% greater.

Toray’s technology will streamline the recovery of valuable metals and make it possible to recover high-purity lithium in high yields. Carbon dioxide emissions from recovering 1kg of lithium through Toray’s nanofiltration membrane are nearly two-thirds lower than from the ore process. 

Toray will collaborate with automakers, battery and battery material manufacturers, recycling companies, and other players to establish a lithium recycling approach. Toray stands to help realize a carbon-neutral economy by eliminating the shortages of lithium that will become a significant concern amid the penetration of electric vehicles.

Toray will continue researching and developing advanced materials that transform societies in keeping with its commitment to innovating ideas, technologies, and products that deliver new value.

Glossary 
1. Evaporation ponds: Lithium is produced by pumping brine from a salt lake, concentrating it under the sun for six to twelve months, and refining it.
2. The ore process extracts lithium by dressing, roasting, leaching, and refining ore after mining.


 

 
东丽株式会社

可从废旧离子池中回收锂成分的分离膜问世
-成功研发出显著提高耐酸性的高锂选择性纳滤膜-

东丽株式会社(总部:京都中央区,代表取缔役社长:日昭广,以下称东丽)此前成功研发出新型纳滤膜(以下称NF膜),该NF膜可以从今后将大量产生的废旧车载离子池中对目前仍多被废弃的锂成分进行有效回收。东丽已开始采用实际溶液对回收的效果进行评估,并为早日用化而加快研发进程

随着电动的普及,预计对锂资源的需求将急上升。但是,目前作为主要锂来源的湖提锂法*1),仅限于锂产量高的盐湖,这成为亟待解决的课题。此外,石提锂法*2)的生产工序长,需要高温热处理,CO2排放量大,成本大幅增加,使得本就存在价格高课题的锂离子池面临价格进一步上涨的风险

NF膜具有将溶解性多价离子及有机物进行选择性分离的特性,不仅可以用于去除地下水及江河水中的硬度成分及农药,还可以用于食品及生物用途的脱盐及精制等。但是,由于以往的NF膜仍存在诸多未解决的难题,如耐酸性较弱,使其适用范围仅限于中性域,而且针对多价离子的选择性分离功能也不充分,无法高效分离。因此,迄今NF膜无法应对废旧离子池中需要使用强酸浸出并收有价金属的作业

东丽通过活用DX,针对因酸而造成膜性能劣化的机理以及选择性分离所需的最佳膜构进行解析后,充分利用有机合成化学、高分子化学以及纳米技,成功开发出兼具牢固的耐酸性构及1纳米以下精密构的交联高分子膜。由此实现了与以往产品相比5倍的耐酸性及1.5倍的离子选择分离性。

通过使用本NF膜,可有效回收有价金属,并可高度及高收率地回收目前大部分被废弃的锂。并且,提取1公斤锂时的CO2排放量最多可以减少到矿石提锂法的1/3左右。

今后东丽将与汽车制造商、电池制造商、电池材料制造商、回收公司等合作,通过确立锂的回收方法,解决电动汽车普及所带来的锂供应课题,努力为实现碳中和社会做出贡献。

东丽通过推进从根本上改变社会的革新性材料的研发活动,以具体的成果践行着我们通过创造新的价值,为社会作贡献这一东丽集团的企业理念。

<用语说明>
1)盐湖提锂法:从盐湖中取水,经过半年到1年半的日晒浓缩及精制工序生产锂的方法。
2)矿石提锂法:矿石开采后,经过选矿、焙烧、浸出、精制工序生产锂的方法。
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