The next major leap in energy storage is thought to arise from a practical implementation of all solid-state batteries, which remain largely confined to the small scale due to issues in manufacturing and mechanical stability. Lithium batteries are amongst the most sought after, for the high expected energy density and improved safety characteristics, however the challenge of finding a suitable solid-state electrolyte remains. Lithium rich garnets are prime contenders as electrolytes, owing to their high ionic conductivity (>0.1 mS cm⁻¹), wide electrochemical window (0–6 V) and stability with Li metal. However, the high Young's modulus of these materials, poor wetting of Li metal and rapid formation of Li₂CO₃ passivating layers tends to give a detrimentally large resistance at the solid–solid interface, limiting their application in solid state batteries. Most studies have focused on La based systems, with very little work on other lanthanides. Here we report a study of the Nd based garnet Ga_0.2Li_6.4Nd₃Zr₂O₁₂, illustrating substantial differences in the interfacial behaviour. This garnet shows very low interfacial resistance attributed to dopant exsolution which, when combined with moderate heating (175 °C, 1 h) with Li metal, we suggest forms Ga–Li eutectics, which significantly reduces the resistance at the Li/garnet interface to as low as 67 Ω cm² (much lower than equivalent La based systems). The material also shows intrinsically high density (93%) and good conductivity (≥0.2 mS cm⁻¹) via conventional furnaces in air. It is suggested these garnets are particularly well suited to provide a mixed conductive interface (in combination with other garnets) which could enable future solid-state batteries.

中文翻译：

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Ga0.2Li6.4Nd3Zr2O12 石榴石的评估：利用掺杂物的不稳定性来创建混合导电界面，以降低全固态电池的界面电阻

能量存储的下一个重大飞跃被认为来自全固态电池的实际应用，由于制造和机械稳定性问题，固态电池在很大程度上仍局限于小规模。锂电池是最受追捧的，因为预期的高能量密度和改进的安全特性，但是寻找合适的固态电解质的挑战仍然存在。富锂石榴石是电解质的主要竞争者，因为它们具有高离子电导率 (>0.1 mS cm ^-1 )、宽电化学窗口 (0-6 V) 和与锂金属的稳定性。然而，这些材料的高杨氏模量、锂金属的润湿性差和快速形成 Li ₂ CO ₃钝化层往往会在固-固界面处产生不利的大电阻，从而限制了它们在固态电池中的应用。大多数研究都集中在基于 La 的系统上，对其他镧系元素的研究很少。在这里，我们报告了对 Nd 基石榴石 Ga _0.2 Li _6.4 Nd ₃ Zr ₂ O _{12 的研究}，说明了界面行为的显着差异。这种石榴石显示出非常低的界面电阻，归因于掺杂剂的溶出，当与锂金属结合适度加热（175°C，1 小时）时，我们建议形成 Ga-Li 共晶，这显着降低了 Li/石榴石界面的电阻低至 67 Ω cm ²（远低于等效的基于 La 的系统）。通过在空气中的传统熔炉，该材料还显示出固有的高密度（93%）和良好的导电性（≥0.2 mS cm ^-1）。建议这些石榴石特别适合提供混合导电界面（与其他石榴石结合），这可以使未来的固态电池成为可能。