• MoSe₂/MoC/C multiphase boundaries boost ionic transfer kinetics.

• MoSe₂ (5–10 nm) with rich edge sites is uniformly coated in N-doped framework.

• The obtained MoSe₂ nanodots achieved ultralong cycle performance in LIBs and high capacity retention in full cell.

Interface engineering has been widely explored to improve the electrochemical performances of composite electrodes, which governs the interface charge transfer, electron transportation, and structural stability. Herein, MoC is incorporated into MoSe₂/C composite as an intermediate phase to alter the bridging between MoSe₂- and nitrogen-doped three-dimensional (3D) carbon framework as MoSe₂/MoC/N–C connection, which greatly improve the structural stability, electronic conductivity, and interfacial charge transfer. Moreover, the incorporation of MoC into the composites inhibits the overgrowth of MoSe₂ nanosheets on the 3D carbon framework, producing much smaller MoSe₂ nanodots. The obtained MoSe₂ nanodots with fewer layers, rich edge sites, and heteroatom doping ensure the good kinetics to promote pseudo-capacitance contributions. Employing as anode material for lithium-ion batteries, it shows ultralong cycle life (with 90% capacity retention after 5000 cycles at 2 A g⁻¹) and excellent rate capability. Moreover, the constructed LiFePO₄//MoSe₂/MoC/N–C full cell exhibits over 86% capacity retention at 2 A g⁻¹ after 300 cycles. The results demonstrate the effectiveness of the interface engineering by incorporation of MoC as interface bridging intermediate to boost the lithium storage capability, which can be extended as a potential general strategy for the interface engineering of composite materials.

• MoSe ₂ / MoC / C多相边界提高了离子转移动力学。

• 具有丰富边缘位置的MoSe ₂（5–10 nm）在N掺杂骨架中均匀地涂覆。

• 所得的MoSe ₂纳米点在LIB中实现了超长循环性能，并在全电池中实现了高容量保留。

界面工程已被广泛探索以改善复合电极的电化学性能，从而控制界面电荷转移，电子传输和结构稳定性。在此，MoC作为中间相掺入MoSe ₂ / C复合材料中，以改变MoSe _2-和氮掺杂的三维（3D）碳骨架之间的桥连，即MoSe ₂ / MoC / N-C连接，从而大大改善了结构稳定性，电子电导率和界面电荷转移。此外，将MoC掺入复合材料可抑制MoSe ₂纳米片在3D碳骨架上的过度生长，从而产生更小的MoSe ₂纳米点。获得的MoSe ₂具有较少层，丰富的边缘位点和杂原子掺杂的纳米点可确保良好的动力学，从而促进伪电容的贡献。作为锂离子电池的负极材料，它显示出超长的循环寿命（在2 A g ^-1下5000次循环后具有90％的容量保持率）和出色的倍率性能。此外，构建的LiFePO ₄ // MoSe ₂ / MoC / NC充满电池在300次循环后在2 A g ^-1下具有超过86％的容量保持率。结果表明，通过将MoC用作界面桥联中间体以增强锂的储存能力，界面工程的有效性，可以将其扩展为复合材料界面工程的潜在一般策略。