Structural Evolution of Layered Manganese Oxysulfides during Reversible Electrochemical Lithium Insertion and Copper Extrusion.
Structural Evolution of Layered Manganese Oxysulfides during Reversible Electrochemical Lithium Insertion and Copper Extrusion.
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DOI：
10.1021/acs.chemmater.1c00375
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发表时间：
2021-06-08
期刊：
影响因子：
--
通讯作者：
Grey CP
中科院分区：
文献类型：
--
作者：
Dey S;Zeng D;Adamson P;Cabana J;Indris S;Lu J;Clarke SJ;Grey CP
用原位粉末X射线衍射和非原位中子粉末衍射、X射线吸收和7Li核磁共振谱相结合的方法，结合一系列的电化学实验，研究了层状硫氧化物Sr2MnO2Cu4−δS3的电化学锂和脱硫化。Sr2MnO2Cu4−δS3由[Sr2MnO2]钙钛矿型阳离子层和高缺陷反萤石型[Cu4−δS3](δ≈0.5)阴离子层交替组成。它与Li的反应经历了复合置换/插层(CDI)机制，其中插入的Li取代了Cu，形成了Li4S3板条，而Cu+被还原并以金属粒子的形式挤压出来。在第一次放电过程的最初2-3%，硫化层中的空位被Li填充；然后，铜挤压伴随着Li的进一步插入。在放电的前半段，Mn2.5+被还原为Mn2+。整个充电过程包括锂的去除和铜在硫化物层中的重新插入，并将Mn2+重新氧化为Mn2.5+。然而，由于锂和铜的扩散系数不同，充电时的过程与首次放电时的过程有很大的不同：充电到2.75V时，锂的大部分被去除，铜的再插入很少，容量保持良好。需要充电到3.75V才能完全重新插入铜，这会导致在随后的放电过程中硫化物亚晶格发生显著变化，容量保持不佳。这种详细的结构-性能研究将促进新的功能电极的设计，提高器件的性能。
The electrochemical lithiation and delithiation of the layered oxysulfide Sr2MnO2Cu4−δS3 has been investigated by using a combination of in situ powder X-ray diffraction and ex situ neutron powder diffraction, X-ray absorption and 7Li NMR spectroscopy, together with a range of electrochemical experiments. Sr2MnO2Cu4−δS3 consists of [Sr2MnO2] perovskite-type cationic layers alternating with highly defective antifluorite-type [Cu4−δS3] (δ ≈ 0.5) anionic layers. It undergoes a combined displacement/intercalation (CDI) mechanism on reaction with Li, where the inserted Li replaces Cu, forming Li4S3 slabs and Cu+ is reduced and extruded as metallic particles. For the initial 2–3% of the first discharge process, the vacant sites in the sulfide layer are filled by Li; Cu extrusion then accompanies further insertion of Li. Mn2.5+ is reduced to Mn2+ during the first half of the discharge. The overall charging process involves the removal of Li and re-insertion of Cu into the sulfide layers with re-oxidation of Mn2+ to Mn2.5+. However, due to the different diffusivities of Li and Cu, the processes operating on charge are quite different from those operating during the first discharge: charging to 2.75 V results in the removal of most of the Li, little reinsertion of Cu, and good capacity retention. A charge to 3.75 V is required to fully reinsert Cu, which results in significant changes to the sulfide sublattice during the following discharge and poor capacity retention. This detailed structure–property investigation will promote the design of new functional electrodes with improved device performance.
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影响因子：
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