リチウム硫黄電池の可能性を解き放つ (Unlocking the Potential of Lithium-Sulfur Batteries)

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2025-01-13 アルゴンヌ国立研究所 (ANL)

アルゴンヌ国立研究所(ANL)の研究者たちは、リチウム-硫黄(Li-S)電池の性能向上に向けた新たな電解質添加剤を開発しました。Li-S電池は、従来のリチウムイオン電池に比べて2~3倍のエネルギー密度を持ち、コスト削減や地球上で豊富に存在する資源の利用が可能とされています。しかし、ポリスルフィドイオンの不適切な移動や化学反応の不均一性により、サイクル寿命が短いという課題がありました。研究チームは、電解質に新しい添加剤を導入することで、これらの問題を軽減し、Li-S電池のエネルギー密度向上、コスト削減、サイクル寿命の延長を実現する可能性を示しました。この成果は、Li-S電池の商業化に向けた重要な一歩とされています。

<関連情報>

ポリスルフィド非相溶添加剤がLi-S電池の空間的反応不均一性を抑制 Polysulfide-incompatible additive suppresses spatial reaction heterogeneity of Li-S batteries

Chen Zhao, Heonjae Jeong, Inhui Hwang, Tianyi Li, Yang Wang, Jianming Bai, Luxi Li, Shiyuan Zhou, Chi Cheung Su, Wenqian Xu, Zhenzhen Yang, Manar Almazrouei, Cheng-Jun Sun, Lei Cheng, Gui-Liang Xu, Khalil Amine
Joule  Available online: 8 October 2024
DOI:https://doi.org/10.1016/j.joule.2024.09.004

Graphical abstract

リチウム硫黄電池の可能性を解き放つ (Unlocking the Potential of Lithium-Sulfur Batteries)

Highlights

  • •Polysulfide-incompatible additive induces in situ CEI construction
  • •Interphase engineering enables effective electrolyte wetting and ion transportation
  • •Synchrotron analysis reveals the correlation between SEI/CEI and cell-level behavior

Context & scale

The ineffective electrolyte wetting and sluggish ion transport in thick tortuous S cathode dramatically hinder lithium-sulfur (Li-S) cell performance, especially under practical high S loading and lean electrolyte conditions. Meanwhile, the insufficient understanding of the relationship between solid/cathode-electrolyte properties and cell-level behavior further limits practical Li-S battery development. To subsequently enhance the electrolyte wetting/ion transportation inside a thick S cathode and deepen the mechanism understanding, in this work, we reveal that the polysulfide-incompatible Lewis acid additive (LAA), which has long been considered unsuitable for Li-S batteries due to the chemical compatibility, can induce the in situ homogeneous interphase layer formation within the tortuous S cathode to promote ion transportation. Our conception is validated by a suite of fundamental investigations, including advanced synchrotron characterization and computational simulations.

Summary

Rational electrolyte engineering for practical pouch cells remains elusive because the correlation between the cathode/solid-electrolyte interphase layer and cell-level reaction behavior is poorly understood. Here, by combining multiscale characterization and computational modeling, we show that—counter to the conventional perception of polysulfide-incompatible additives—the spontaneous reaction of sparingly solvated polysulfides with Lewis acid additives (LAAs) can induce in situ formation of a homogeneous interphase on thick and tortuous S cathode. Multiscale synchrotron X-ray characterization consistently affirms that such interface design could effectively eliminate the notorious problems of polysulfide shuttle and lithium corrosion and, more importantly, provide an interconnected “ion transport highway” to alleviate the uneven ion transport within the tortuous S cathode. Hence, this design dramatically reduces the reaction heterogeneity of lithium-sulfur (Li-S) pouch cells under lean electrolyte conditions. This work resolves controversy around the role of polysulfide-incompatible additives in high-energy Li-S pouch cells and highlights the importance of suppressing reaction heterogeneity for practical batteries.

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