基于操作和原位 XRD 测量的锂-O2 电池阴极放电和充电反应分析,The Journal of Physical Chemistry C

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基于操作和原位 XRD 测量的锂-O2 电池阴极放电和充电反应分析
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-07-26 , DOI: 10.1021/acs.jpcc.3c02808
Makoto Aoki ₁ , Dilinigeer Dilixiati ₂ , Minako Ushijima ₂ , Suzumi Yamada ₂ , Toshihiro Kondo _{1,

2}

Affiliation

详细讨论了Li-O ₂电池正极的放电和充电反应，并基于操作/原位XRD获得了Li 2- x O 2 中的x值，Li _{2- x}_{O 2}是放电过程中的主要产物测量以及 Rietveld 分析。明确了放电初期形成P 6 ₃ / mmc空间群型LiO _{2 ，然后形成Li}_{2– x} O ₂沉积伴随着锂占有率的增加，以及c晶格参数和沿a轴方向的磁畴尺寸的各向异性变化。_{充电过程也被阐明，未溶解的Li 2- x} O ₂中的x值随着晶格参数和域形状的轻微变化而降低。基于放电电流密度、放电量和循环次数的依赖性，总体反应建议如下。放电过程中，电化学形成非晶态 Li ₂ O ₂、晶态 Li _{2– x} O ₂和副反应产物（最有可能是 Li ₂ CO ₃）同时发生。在充电过程中，无定形Li ₂ O ₂首先氧化溶解，然后是结晶Li _{2- x} O ₂，最后Li ₂ CO ₃溶解和/或分解。由于最后的Li ₂ CO ₃部分未溶解在正极表面，导致下次放电过程中生成的结晶Li _{2– x} O ₂的比例下降，导致循环性能较差。

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Discharging and Charging Reaction Analyses at the Cathode for a Lithium–O2 Battery Based on Operando and In Situ XRD Measurements

The discharging and charging reactions at the cathode of the Li–O₂ battery were discussed in detail, and the x values in Li_2–xO₂ were obtained, which is a major product during discharging, based on the operando/in situ XRD measurements along with the Rietveld analyses. It was clarified that the P6₃/mmc space group-type LiO₂ was formed during the initial stage of discharge, and then Li_2–xO₂ was deposited accompanied by an increase in lithium occupancy with an anisotropic change in the c-lattice parameter and domain size along the a-axis direction. The charging process was also clarified such that the x value in the undissolved Li_2–xO₂ decreased with slight changes in the lattice parameters and domain shapes. Based on the dependences of the discharging current density, discharging amount, and cycle number, the overall reaction was proposed as follows. During discharging, the electrochemical formation of amorphous Li₂O₂, crystalline Li_2–xO₂, and side-reaction products (most likely Li₂CO₃) simultaneously occurred. During charging, amorphous Li₂O₂ is oxidatively dissolved first, followed by crystalline Li_2–xO₂, and finally Li₂CO₃ dissolved and/or decomposed. Since part of the last Li₂CO₃ remained undissolved on the cathode surface, the proportion of the crystalline Li_2–xO₂ generated during the next discharging process decreased, leading to poor cyclability.

更新日期：2023-07-26

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