高性能バッテリー設計の新しい青写真(A new blueprint for designing high-performance batteries)

2023-11-15

2023-11-14 アルゴンヌ国立研究所(ANL)

◆アルゴンヌ国立研究所の科学者チームが、亜鉛イオン電池の電解液において複雑な成分の中で起こる「協力的な」挙動を発見。異なる種類のアニオンとカチオンの組み合わせが電池の性能向上に寄与し、イオンの選択によって電池の特性を調整可能。
◆これは多価電池の研究であり、亜鉛などの+2の電荷を持つカチオンを使用し、より多くのエネルギーを蓄え放出できるため、電気自動車や電力グリッド貯蔵に有望。異なるアニオン組み合わせの探求が電池開発者により精密な制御を提供し、電気生成と貯蔵の効率向上が期待されている。

＜関連情報＞

複数のアニオンを含む非水電解質における創発的溶媒和現象 Emergent solvation phenomena in non-aqueous electrolytes with multiple anions

Darren M. DriscollSydney N. LavanMilena ZorkoPaul C. RedfernStefan IlicGarvit AgarwalTimothy T. FisterRajeev S. AssaryLei ChengDusan StrmcnikMahalingam BalasubramanianJustin G. Connell
Chem Published:April 19, 2023
DOI:https://doi.org/10.1016/j.chempr.2023.03.021

Highlights

•Mixing of halide and organic anions induces an emergent Zn²⁺ coordination environment
•Bulk electrolyte coordination directly influences the metal deposition kinetics on electrodes
•Decreasing halide association strength correlates with increasing redox activation

Summary

As the search for new battery chemistries with higher capacities and more stable supply chains expands, requiring increasingly complex electrolytes with multiple solvents and anions, it is becoming clear that understanding and controlling the working cation solvation structure is key to enabling improved stability and reversibility. In this work, we discover an emergent solvation behavior in multivalent electrolytes containing multiple anions, where bis(trifluoromethane sulfonyl) imide (TFSI⁻) anions that are fully dissociated in isolation form contact ion pairs with Zn²⁺ when combined with more strongly coordinating halides. This coordination modifies the electrochemical response, activating additional redox species as the halide association strength weakens (i.e., Cl⁻ > Br⁻ > I⁻) and systematically lowering overpotentials for metal deposition. This work suggests a completely new framework for electrolyte design in which anion chemistry can be used to tune both the bulk speciation and the interfacial solvation structure, enabling profound changes to the electrochemical behavior of the system.