Li₇La₃Zr_2.0O₁₂ (LLZO) garnets have many properties of a suitable solid electrolyte for lithium ion batteries; however, drawbacks like their low ionic conductivity and poor interfacial properties still hinder their broadened application. Current research has sought to both increase their ionic conductivity and density their microstructure, which are two important factors relating to their practical application. This study presents a facile and effective way to obtain compact LLZO with high Li⁺ conductivity via a one-step multi-elemental doping strategy, using Nb⁵⁺ and Ga³⁺ as dopants simultaneously. Garnet-structured oxides with the nominal chemical composition of Li_6.8−3xGa_xLa₃Zr_1.8Nb_0.2O₁₂ (x = 0, 0.1, 0.15, 0.2, 0.25, and 0.3) are prepared via a conventional solid-state reaction, and the effects of the two dopants on the oxides are investigated based on the phase compositions, morphologies and Li ion conductivities. Benefitting from Li⁺ vacancies generated by the addition of the two elements, garnets sintered with an optimized amount of Ga/Nb dopant can exhibit relative densities of 93–95% and a peak conductivity of 1.42 × 10⁻³ S cm⁻¹ at 50 °C. In a symmetric Li/LLZO/Li cell, this dense structured electrolyte shows a low overpotential and superior electrochemical stability to Li metal, exhibiting good performance for over 200 h at a current density of 100 μA cm⁻¹ during Li plating/stripping cycles. Also, this co-doped solid-state electrolyte can exhibit acceptable cycling stability when paired with a LiNi_0.33Mn_0.33Co_0.33O₂ (NMC111) cathode, both with the help of liquid electrolyte and when assembled as an all-solid-state battery. We believe this research can provide some new insights into developing solid-state electrolyte-based lithium ion batteries.

中文翻译：

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通过Ga / Nb双重替代实现高Li +电导率和致密微观结构的Li7La3Zr2O12石榴石，用于锂固态电池应用

Li ₇ La ₃ Zr _2.0 O ₁₂（LLZO）石榴石具有许多适合锂离子电池的固体电解质的特性；但是，诸如离子导电率低和界面性能差等缺点仍然阻碍了它们的广泛应用。当前的研究试图增加其离子电导率并提高其微结构的密度，这是与它们的实际应用有关的两个重要因素。这项研究提出了一种简便而得到高李紧凑LLZO有效途径⁺导电通过一步法多元素掺杂策略，利用铌⁵⁺和Ga ³⁺同时作为掺杂剂。通过常规固态反应制备标称化学成分为_{6.8-3 x} Ga _x La ₃ Zr _1.8 Nb _0.2 O ₁₂（x = _{0、0.1、0.15、0.2、0.25}和0.3）的石榴石结构氧化物，并根据相组成，形貌和锂离子电导率研究了两种掺杂剂对氧化物的影响。受益于通过添加这两种元素而产生的Li ⁺空位，石榴石与最适量的Ga / Nb掺杂剂烧结后可表现出93-95％的相对密度和1.42×10 ^-3 S cm的峰值电导率^-1在50°C下。在对称的Li / LLZO / Li电池中，这种致密的结构化电解质表现出比Li金属低的过电势和优异的电化学稳定性，在Li电镀/剥离循环中的电流密度为100μAcm ^-1的情况下，在200小时内表现出良好的性能。同样，当与LiNi _0.33 Mn _0.33 Co _0.33 O ₂（NMC111）阴极配对使用时，在液体电解质的帮助下和组装为全固态电池时，这种共掺杂固态电解质也可以显示出可接受的循环稳定性。。我们相信这项研究可以为开发基于固态电解质的锂离子电池提供一些新见解。