Sodium-oxygen batteries are emerging as a new energy storage system because of their high energy density and low cost. However, the cycling performance of the battery is not satisfying due to its insulating discharge product. Here, we synthesized metallic phosphides with gradient concentration (g-CoNiFe-P) and their uniform counterpart (CoNiFe-P) as cathode catalysts in a Na–O₂ battery. Notably, the distribution of relaxation time (DRT) was utilized to identify the rate-determining step in a Na–O₂ battery, evaluate the catalytic performance of the catalysts, and monitor the change of every single electrochemical process along the whole cycling process to study the degradation mechanism. The g-CoNiFe-P catalyst presented better initial capacity and cycling performances. The evolution of the kinetic processes resulting in battery degradation has been investigated by DRT analysis, which assists with characterizations. Our work demonstrates the application of DRT in battery diagnosis to evaluate the catalytic performance of catalysts and monitor the changes in different kinetic processes of new energy systems.

中文翻译：

---

通过弛豫时间分布评价钠空气电池多金属磷化物阴极


钠氧电池因其高能量密度和低成本而成为一种新兴的储能系统。然而，由于其绝缘放电产物，电池的循环性能并不令人满意。在这里，我们合成了具有梯度浓度的金属磷化物（g-CoNiFe-P）及其均匀对应物（CoNiFe-P）作为Na-O ₂ 电池中的阴极催化剂。值得注意的是，弛豫时间（DRT）的分布被用来识别Na-O ₂ 电池中的速率决定步骤，评估催化剂的催化性能，并监测每个电化学过程的变化沿着整个循环过程研究降解机制。 g-CoNiFe-P催化剂表现出更好的初始容量和循环性能。导致电池退化的动力学过程的演变已通过 DRT 分析进行了研究，这有助于表征。我们的工作展示了DRT在电池诊断中的应用，以评估催化剂的催化性能并监测新能源系统不同动力学过程的变化。