Heterostructure construction is an efficient method for reinforcing K⁺ storage of transition metal selenides. The spontaneously developed internal electric fields give a strong boost to charge transport and significantly reduce the activation energy. Nevertheless, perfection of the interfacial region based on the energy level gradient and lattice matching degree is still a great challenge. Herein, rich vacancies and ultrafine CoSe₂–FeSe₂ heterojunctions with semicoherent phase boundary are simultaneously obtained, which possess unique electronic structures and abundant active sites. When employed as anodes for potassium-ion batteries (PIBs), CoSe₂–FeSe₂@C composites display a reversible potassium storage of 401.1 mAh g⁻¹ at 100 mA g⁻¹ and even 275 mAh g⁻¹ at 2 A g⁻¹. Theoretical calculation also reveals that the potassium-ion diffusion can be dramatically promoted by the controllable CoSe₂–FeSe₂ heterojunction.

中文翻译：

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具有半相干相边界的可控异质结促进 CoSe2/FeSe2 的钾存储

异质结构构建是增强过渡金属硒化物K ⁺存储的有效方法。自发形成的内部电场极大地促进了电荷传输并显着降低了活化能。尽管如此，基于能级梯度和晶格匹配度的界面区域的完善仍然是一个巨大的挑战。在此，同时获得了具有半相干相界的丰富空位和超细CoSe ₂ -FeSe ₂异质结，它们具有独特的电子结构和丰富的活性位点。当用作钾离子电池 (PIB) 的阳极时，CoSe ₂ –FeSe ₂@C复合材料显示的可逆钾存储的401.1毫安克^-1在100mA克^-1和甚至275毫安克^-1以2A克^-1。理论计算还表明，可控的CoSe ₂ -FeSe ₂异质结可以显着促进钾离子扩散。