Binary metal oxides have received sustained interest as anode materials due to their desirable capacities, exceeding theoretical values particularly in the first discharge. Although they have received increasing attention in recent years, topical debates persist regarding not only their lithiation mechanisms but also the origin of additional capacity. Aiming to resolve these disagreements, we perform a systematic study of a series of iron and manganese oxides to investigate their phase behavior during first discharge. Using a combination of in operando pair distribution function measurements and our recently developed Metropolis non-negative matrix factorization approach to address the analytical challenges concerning materials’ nanoscopic nature and phase heterogeneity, here we report unexpected observation of non-equilibrium FeO_x solid-solution phases and pulverization of MnO. These processes are correlated with the extra capacities observed at different depths of discharge, pointing to a metal-dependent nature of this additional capacity and demonstrating the advantage of our approach with promising prospects for diverse applications.

由于其理想的容量，尤其是在第一次放电中超过理论值，二元金属氧化物作为负极材料受到了持续的关注。尽管近年来它们受到越来越多的关注，但关于它们的锂化机制以及额外容量的起源的热门辩论仍然存在。为了解决这些分歧，我们对一系列铁和锰的氧化物进行了系统研究，以研究它们在首次放电过程中的相行为。使用的组合在operando对分布函数测量和我们最近开发的 Metropolis 非负矩阵分解方法来解决有关材料纳米性质和相异质性的分析挑战，在这里我们报告了对非平衡 FeO _x固溶体相和 MnO 粉化的意外观察。这些过程与在不同放电深度观察到的额外容量相关，表明这种额外容量的金属依赖性，并证明了我们的方法具有多种应用前景的优势。