Na5.6Zn0.6Ga0.4S4, which retains the crystalline structure of its parent form Na6ZnS4, is described as a new class of Na-conducting solid-state electrolytes (SSEs) for all-solid-state batteries. We demonstrate that while Na6ZnS4 is ionically insulating (1.4 nS cm-1), Ga-substitution results in an astonishing improvement of ionic conductivity (σion) to 70.1 μS cm-1, making Na5.6Zn0.6Ga0.4S4 a practical SSE. This dramatic increase in σion (5 × 104 fold) is associated with an increased Na+ occupancy in interstitial sites as ‘x’ increases in Na6-xZn1-xGaxS4, where interstitial Na ions facilitate long-range Na+ conduction, which is otherwise immobile. Ga-substitution also results in phase-pure Na6-xZn1-xGaxS4, contributing at least partially to the enhancement of σion. Furthermore, Na6-xZn1-xGaxS4 exhibits neither releasing H2S gas nor compromising its crystalline structure for several hours under ambient conditions. Ga-substitution also enhances electrochemical stability. While the anodic limit remains largely unchanged, the cathodic limit is significantly lowered from 0.99 V vs. Na2Sn in Na6ZnS4 to 0.35 V in Na5.6Zn0.6Ga0.4S4, resulting in stable Na alloying/dealloying reactions in a symmetric Na2Sn ‖ Na2Sn cell. These findings are comprehensively supported by various experimental and theoretical methods. Finally, we construct a full cell (Na2Sn ‖ TiS2) and demonstrate the practicality of Na5.6Zn0.6Ga0.4S4 as a promising SSE in all solid-state Na ion batteries.

中文翻译：

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通过间隙位点工程在用于 Na 导电固态电解质的绝缘 Na6ZnS4 中创建导电通道


Na5.6Zn0.6Ga0.4S4 保留了其母体 Na6ZnS4 的晶体结构，被描述为一类用于全固态电池的新型 Na 导电固态电解质 （SSE）。我们证明，虽然 Na6ZnS4 具有离子绝缘性 （1.4 nS cm-1），但 Ga-取代导致离子电导率 （σion） 惊人地提高到 70.1 μS cm-1，使 Na5.6Zn0.6Ga0.4S4 成为实用的 SSE。σion 的这种急剧增加（5 × 104 倍）与间质部位的 Na+ 占有率增加有关，因为 Na6-xZn1-xGaxS4 的“x”增加，其中间质 Na 离子促进长程 Na+ 传导，否则它是不动的。Ga-取代还导致相纯 Na6-xZn1-xGaxS4，至少部分有助于 σion 的增强。此外，Na6-xZn1-xGaxS4 在环境条件下数小时内既不释放 H2S 气体，也不损害其晶体结构。Ga-取代还增强了电化学稳定性。虽然阳极极限基本保持不变，但阴极极限从 Na6ZnS4 中的 0.99 V vs. Na2Sn 显著降低到 Na5.6Zn0.6Ga0.4S4 中的 0.35 V，从而在对称的 Na2Sn ‖ Na2Sn 电池中产生稳定的 Na 合金化/脱合金反应。这些发现得到了各种实验和理论方法的全面支持。最后，我们构建了一个全电池 （Na2Sn ‖ TiS2） 并证明了 Na5.6Zn0.6Ga0.4S4 在所有固态 Na 离子电池中作为有前途的 SSE 的实用性。