Batteries with intercalation-conversion-type electrodes tend to achieve high-capacity storage, but the complicated reaction process often suffers from confusing electrochemical mechanisms. Here, we reinterpreted the essential issue about the potential of the conversion reaction and whether there is an intercalation reaction in a lithium/sodium-ion battery (LIB/SIB) with the FeP anode based on the evolution of the magnetic phase. Especially, the ever-present intercalation process in a large voltage range followed by the conversion reaction with extremely low potential was confirmed in FeP LIB, while it is mainly the conversion reaction for the sodium storage mechanism in FeP SIB. The insufficient conversion reaction profoundly limits the actual capacity to the expectedly respectable value. Accordingly, a graphene oxide modification strategy was proposed to increase the reversible capacity of FeP LIB/SIB by 99% and 132%, respectively. The results facilitate the development of anode materials with a high capacity and low operating potential.

中文翻译：

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从磁相演化重新解读锂/钠离子电池中FeP负极的插层转化机制

具有插层转换型电极的电池往往能够实现高容量存储，但复杂的反应过程往往会受到电化学机制的困扰。在这里，我们基于磁相的演化，重新解释了 FeP 负极的锂/钠离子电池（LIB/SIB）中转化反应的潜力以及是否存在嵌入反应的基本问题。特别是，在FeP LIB中证实了一直存在的大电压范围内的嵌入过程，随后发生极低电位的转化反应，而FeP SIB中主要是钠储存机制的转化反应。不充分的转化反应极大地将实际容量限制在预期的可观值。因此，提出了氧化石墨烯改性策略，将 FeP LIB/SIB 的可逆容量分别提高了 99% 和 132%。这些结果有助于开发具有高容量和低工作电位的负极材料。