In situ transition metal oxide doping for simultaneous conductivity enhancement and structural stabilization of silicon‑carbon anodes

Silicon has an ultra-high lithium storage capacity far exceeding that of widely used graphite anodes, and is a strong contender to replace graphite anodes because of its abundant resources. Nevertheless, the salient volume increase and shrinkage at the alloying reaction process, low conductivity of the silicon anode greatly affect its large-scale development in the anode direction of lithium-ion batteries (LIBs). To overcome these shortcomings, a molybdenum oxide-doped silicon‑carbon composite (Mo-Si@C) was developed using simple ball milling combined with low-temperature carbonization. The unique layered structure of MoO 3 exhibits an excellent physical buffering effect, providing a large number of high-activity lithium storage sites while effectively inhibiting the expansion and rupture of silicon particles. This structure can generate a highly conductive phase in situ, enhancing the charge transmission capability of the anodes. DFT calculations reveal that the Mo-Si@C anode possesses larger interlayer binding energies between silicon and carbon layer, increased density of states due to d -orbital contributions, and the highest adsorption energy toward Li + , suggesting the suppressive volume variation, enhanced conductivity and reaction dynamics of the Mo-Si@C anode. Results of the Experiment indicate that the optimized Mo-Si@C composite exhibits 668 mAh g −1 remaining capacity after 200 cycles at 0.2 A g −1 current density, demonstrating remarkable electrochemical properties and structural stability, which provides a friendly approach for us to design a promising silicon‑carbon anode with high-performance and low-cost LIBs. We successfully doped MoO ₓ into Si@C materials by ball milling combined with low-temperature carbonization, where MoO ₓ ( x = 2, 3) generates a highly conductive phase Mo in-situ during charging and discharging (a process that occurs before the formation of the lithium-silicon alloys), and the lamellar structure of MoO 3 contributes to the rapid transport of Li + while assisting the carbon layer to limiting the silicon volume expansion. Based on DFT calculations, the formed strong hybridization between Co-3 d /Mo-3 d and the silicon/carbon states creates new active sites, modulating the electronic distribution and improving the coupling with Li + ions, thus essentially promoting the redox reaction kinetics of the electrode system. • Mo-Si@C was prepared by ball milling and low-temperature carbonization. • introduction of d -orbitals (Co-3 d /Mo-3 d ) results in an increased density of states. • In situ generation of highly conductive phase Mo constructs conductive networks. • DFT calculations indicate MoOₓ-doping improves the lithium adsorption ability.