深入了解 FeS2 放电后 Li2FeS2 的电化学性质,Physical Chemistry Chemical Physics

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深入了解 FeS2 放电后 Li2FeS2 的电化学性质
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-03-03 , DOI: 10.1039/d2cp05930d
Cheng-Dong Wei ₁ , Hong-Tao Xue _{1,

2} , Xu-Dong Zhao ₁ , Fu-Ling Tang _{1,

2}

Affiliation

全固态锂硫电池 (ASSLSB) 具有高氧化还原电位、高理论容量、高电子电导率和正极低 Li + 扩散能垒，因此具有高可逆^特性。基于第一性原理高通量计算的簇扩展蒙特卡罗模拟预测了充电过程中相结构从 Li ₂ FeS ₂ ( P [3 结合马克龙]

M 1 ) 到 FeS ₂ ( PA ) 的变化。 [3 结合马克龙]

LiFeS ₂是最稳定的相结构。充电后Li ₂ FeS ₂的结构为FeS ₂ ( P [3 结合马克龙]

M1). 通过应用第一性原理计算，我们探索了充电后Li ₂ FeS _{2的电化学性质。}_{Li 2} FeS ₂的氧化还原反应电位为1.64至2.90 V，表明ASSLSBs的输出电压高。较平坦的电压阶跃平台对于提高阴极的电化学性能很重要。_{充电电压平台从 Li 0.25} FeS ₂到 FeS ₂最高，其次是从 Li _0.375 FeS ₂到 Li _0.25 FeS ₂。_{Li x} FeS ₂的电学性质在 Li ₂ FeS ₂充电过程中保持金属。_{Li 2} FeS ₂本征Li Frenkel缺陷比Li ₂ S肖特基缺陷更有利于Li ^+扩散，Li⁺扩散系数最大。正极良好的电子导电性和Li ⁺扩散系数意味着ASSLSBs具有更好的充放电倍率性能。该工作从理论上验证了Li ₂ FeS ₂充电后的FeS _{2结构，并探索了Li}₂ FeS ₂的电化学性质。

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Insights into the electrochemical properties of Li2FeS2 after FeS2 discharging

All-solid-state lithium–sulfur batteries (ASSLSBs) have high reversible characteristics owing to the high redox potential, high theoretical capacity, high electronic conductivity, and low Li⁺ diffusion energy barrier in the cathode. Monte Carlo simulations with cluster expansion, based on the first-principles high-throughput calculations, predicted a phase structure change from Li₂FeS₂ (P [3 with combining macron]

M1) to FeS₂ (PA [3 with combining macron]

) during the charging process. LiFeS₂ is the most stable phase structure. The structure of Li₂FeS₂ after charging was FeS₂ (P [3 with combining macron]

M1). By applying the first-principles calculations, we explored the electrochemical properties of Li₂FeS₂ after charging. The redox reaction potential of Li₂FeS₂ was 1.64 to 2.90 V, implying a high output voltage of ASSLSBs. Flatter voltage step plateaus are important for improving the electrochemical performance of the cathode. The charge voltage plateau was the highest from Li_0.25FeS₂ to FeS₂ and followed from Li_0.375FeS₂ to Li_0.25FeS₂. The electrical properties of Li_xFeS₂ remained metallic during the Li₂FeS₂ charging process. The intrinsic Li Frenkel defect of Li₂FeS₂ was more conducive to Li⁺ diffusion than that of the Li₂S Schottky defect and had the largest Li⁺ diffusion coefficient. The good electronic conductivity and Li⁺ diffusion coefficient of the cathode implied a better charging/discharging rate performance of ASSLSBs. This work theoretically verified the FeS₂ structure after Li₂FeS₂ charging and explored the electrochemical properties of Li₂FeS₂.

更新日期：2023-03-08

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