Ji Yong Jun, Park Yong Joon
Department of Advanced Materials Engineering, Kyonggi University, 154-42, Gwanggyosan-Ro, Yeongtong-Gu, Suwon-Si, Gyeonggi-Do 16227, Republic of Korea.
ACS Omega. 2024 Feb 5;9(7):8405-8416. doi: 10.1021/acsomega.3c09545. eCollection 2024 Feb 20.
Recently, sulfide solid-state electrolytes with excellent ionic conductivity and facile electrode integration have gained prominence in the field of all-solid-state batteries (ASSBs). However, owing to their inherently high reactivity, sulfide electrolytes interact with the cathode, forming interfacial layers that adversely affect the electrochemical performance of all-solid-state cells. Unlike conventional cathode-coating methods that involve the formation of surface coatings from high-cost source materials, the proposed strategy involves the doping of precursors with low-cost oxides (NbO, TaO, and LaO) prior to cathode fabrication. This novel approach aims to improve the stability of the cathode-sulfide electrolyte interface. Notably, doping significantly improved the discharge capacity, rate capability, and cyclic performance of cathodes while reducing their impedance resistance. Scanning electron microscopy, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) indicated a gradient dopant-concentration profile (with a high level of dopant at the surface) in the doped cathodes. Cathode doping, particularly with Nb and Ta, caused a reduction in cation mixing owing to crystal-structure adjustments and ionic-conductivity enhancements. XPS and high-resolution TEM confirmed that gradient doping effectively minimized cathodic side reactions, possibly due to the formation of a coating-like protective layer in the cathode-electrolyte interface coupled with structural stabilization attributed to the doping process. The protective ability of the interfacial layer generated by gradient doping was confirmed to be comparable to that of conventional surface coatings. Therefore, this study could guide the future development of low-cost, high-performance ASSBs, opening new frontiers in sustainable energy storage.
最近，具有优异离子导电性和易于电极集成的硫化物固态电解质在全固态电池（ASSB）领域中备受瞩目。然而，由于其固有的高反应活性，硫化物电解质会与阴极相互作用，形成界面层，对全固态电池的电化学性能产生不利影响。与传统的阴极涂层方法不同，传统方法涉及使用高成本原料形成表面涂层，而所提出的策略是在阴极制造之前用低成本氧化物（NbO、TaO和LaO）对前驱体进行掺杂。这种新颖的方法旨在提高阴极 - 硫化物电解质界面的稳定性。值得注意的是，掺杂显著提高了阴极的放电容量、倍率性能和循环性能，同时降低了其阻抗。扫描电子显微镜、透射电子显微镜（TEM）和X射线光电子能谱（XPS）表明，掺杂阴极中存在梯度掺杂剂浓度分布（表面掺杂剂水平较高）。阴极掺杂，特别是用Nb和Ta掺杂，由于晶体结构调整和离子电导率提高，导致阳离子混合减少。XPS和高分辨率TEM证实，梯度掺杂有效地减少了阴极副反应，这可能是由于在阴极 - 电解质界面形成了类似涂层的保护层，以及掺杂过程导致的结构稳定。梯度掺杂产生的界面层的保护能力被证实与传统表面涂层相当。因此，这项研究可以指导低成本、高性能全固态电池的未来发展，为可持续储能开辟新的前沿领域。
