Mn-based oxides have attracted extensive attention as electrode materials. However, the irreversible phase transition and Mn²⁺ dissolution result in their structure instability and performance decay. Here, we report dual interphase layers in situ formed on P2-K_0.67MnO₂ (P2-KMO) in 6.0 M of potassium bis(fluorosulfonyl)amide in diglyme (KFSI/G2) during charging. It is composed of a solid-electrolyte interphase (SEI) and K-poor spinel interlayer on P2-KMO, which are derived from the simultaneous decomposition of 6.0 M KFSI/G2 and disproportionation of surface Mn³⁺. They cooperatively enable the reversible phase transition of P2↔P″2 in the bulk P2-KMO and mitigate Mn loss. This leads to a high capacity retention of 90.5% and a Coulombic efficiency of 100% after 300 cycles. The investigation highlights the significance of interphase chemistry of electrode materials for potassium-ion batteries and beyond.

Mn基氧化物作为电极材料引起了广泛的关注。然而，不可逆的相变和Mn ^2+的溶解导致它们的结构不稳定和性能下降。在这里，我们报告在充电期间在6.0 M的二甘醇二甲醚（KFSI / G2）中的双（氟磺酰基）酰胺钾中的P2-K _0.67 MnO ₂（P2-KMO）上原位形成了双相间层。它由P2-KMO上的固体电解质中间相（SEI）和贫K尖晶石中间层组成，这是由6.0 M KFSI / G2同时分解和表面Mn ³⁺歧化而产生的。它们共同实现了P2-KMO本体中P2↔P''2的可逆相变，并减轻了Mn的损失。这导致300个循环后的90.5％的高容量保持率和100％的库仑效率。这项研究突显了钾离子电池及其他材料的电极材料间相化学的重要性。