Microstructure adjustment plays a crucial role in improving the surface reactivity of materials. However, surface reactivity improved by alkali metal doping for electrode materials applied in energy storage is usually overlooked by researchers. Herein, we report on facile synthesis of Li+/Na+-doped GaN microcrystals and their structure–electrochemical performance relationship. The dosage concentration is optimized, and the doping mechanism is proposed in terms of the metathesis reaction of Li2O/Na2O with GaN under carbothermal reduction conditions using LiNO3/NaNO3 as the dopants. Both macro- and microstructures of GaN can be tuned through Li+/Na+ doping. In addition to the increased specific surface area and total pore volume, the reduced d band center and band gap caused by Li+/Na+ doping present an anti-d band center phenomenon and contribute to enhanced ion storage and transport, leading to excellent electrochemical performance of the target materials. In addition, symmetric electrochemical capacitors with the target materials can deliver output voltage of 2.4, 1.5, and 1.0 V at –60, 25, and 120 °C by using phosphoric acid–water–dimethyl sulfoxide mixed solution as the electrolyte. The symmetric electrochemical capacitors with Na+-doped GaN can deliver specific energy of 45.9 mW h cm−3 at 344 mW cm−3 and –60 °C, 36.1 mW h cm−3 at 215 mW cm−3 and 25 °C, and 16.7 mW h cm−3 at 287 mW cm−3 and 120 °C, respectively, holding considerable promise for practice in all-temperature environment.

中文翻译：

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用于超快电化学电容器的碱金属离子掺杂GaN的掺杂机理、结构调整及结构-性能关系


微观结构调整在提高材料的表面反应性方面起着至关重要的作用。然而，研究人员通常忽视了碱金属掺杂对用于储能的电极材料的表面反应性改善。在此，我们报道了 Li+/Na+ 掺杂 GaN 微晶的简单合成及其结构-电化学性能关系。优化了剂量浓度，并以 LiNO3/NaNO3 为掺杂剂，在碳热还原条件下 Li2O/Na2O 与 GaN 的复分解反应提出了掺杂机理。GaN 的宏观和微观结构都可以通过 Li+/Na+ 掺杂进行调整。除了增加比表面积和总孔体积外，Li+/Na+ 掺杂引起的 d 带中心和带隙减小还呈现出反 d 带中心现象，有助于增强离子储存和传输，从而获得优异的靶材电化学性能。此外，使用磷酸-水-二甲基亚砜混合溶液作为电解质，与目标材料对称的电化学电容器可以在 –60、25 和 120 °C 下提供 2.4、1.5 和 1.0 V 的输出电压。采用 Na+ 掺杂 GaN 的对称电化学电容器在 344 mW cm-3 和 –60 °C 下可提供 45.9 mW h cm-3 的比能量，在 215 mW cm-3 和 25 °C 时可提供 36.1 mW h cm-3 的比能量，在 287 mW cm-3 和 120 °C 时分别提供 16.7 mW h cm-3 的比能量，在全温环境中具有相当大的实践前景。