Yuan Hao, Zhang Yong-Wei
Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore.
ACS Appl Mater Interfaces. 2022 Apr 13;14(14):16178-16184. doi: 10.1021/acsami.1c24801. Epub 2022 Apr 3.
Lithium-sulfur (Li-S) and sodium-sulfur (Na-S) batteries, with the advantages of ultrahigh energy density, natural abundance, and ecofriendliness, are regarded as next-generation rechargeable batteries. However, polysulfide shuttling and sluggish charging/discharging kinetics in sulfur cathodes severely hamper their practical applications. In this study, via employing first-principles calculations, we investigate two-dimensional ferroelectric InSe as a promising additive to overcome these obstacles. Our studies reveal the following findings: (1) the InSe monolayer has a modest adsorption strength to soluble polysulfides, which not only eliminates the notorious shuttle effect but also prevents polysulfide dissolution; (2) InSe is able to significantly reduce the free energy barriers of sulfur reduction reaction and the decomposition barriers of LiS and NaS, thus greatly enhancing the charging and discharging efficiency; and (3) due to the strong binding ability, the polarization downward (P↓) surface always outperforms the polarization upward (P↑) surface during charging/discharging processes, enabling the effective control of battery performance by ferroelectric switching. Given these advantages, it is expected that ferroelectric InSe and similar ferroelectric additives will open a new route to enhance Li-S and Na-S battery performance.
锂硫（Li-S）电池和钠硫（Na-S）电池具有超高能量密度、天然丰度高和环境友好等优点，被视为下一代可充电电池。然而，硫正极中的多硫化物穿梭效应以及缓慢的充放电动力学严重阻碍了它们的实际应用。在本研究中，我们通过第一性原理计算，研究了二维铁电体InSe作为克服这些障碍的有前景的添加剂。我们的研究揭示了以下发现：（1）InSe单层对可溶性多硫化物具有适度的吸附强度，这不仅消除了臭名昭著的穿梭效应，还防止了多硫化物溶解；（2）InSe能够显著降低硫还原反应的自由能垒以及LiS和NaS的分解能垒，从而大大提高充放电效率；（3）由于具有强结合能力，在充放电过程中，向下极化（P↓）的表面总是优于向上极化（P↑）的表面，这使得通过铁电开关能够有效控制电池性能。鉴于这些优点，预计铁电体InSe和类似的铁电添加剂将为提高Li-S和Na-S电池性能开辟一条新途径。
