The fast capacity degradation of silicon‐based anodes significantly limits the application in lithium‐ion battery (LIB) industries. Recently, Si−CuO composites have been reported as promising anodes in terms of being cost‐effective and technically feasible, but improved cycle stability is still desired. This work introduces a proper amount of NiO into the Si−CuO composites via a facile high‐energy ball‐milling method. The study reveals that compared to the binary Si‐CuO composites, Si−CuO−NiO samples have less pronounced volume change during the cycles due to the formation of rich‐Si NiSi2. More specifically, Si87.5(CuO)3.4(NiO)9.1 shows the highest 100‐cycle capacity retention of ∼86.9 % at 0.2 C with an average coulombic efficiency of ∼99.4 %. Moreover, the thermal stability investigation demonstrates that the temperature of 600 °C is suitable to coat a carbon layer on Si87.5(CuO)3.4(NiO)9.1, where the microstructure and the uniform element distribution produced in the milling process as well as the suppression to the cr‐Li3.75Si formation can be maintained to the maximum extent, thus with further enhanced electrochemical performance.

A two-step modification for the electrochemical performance of Si-based anodes for LIBs is achieved in this study. Firstly, the Cr element is chosen as the doped media into Si bulk via a HEBM method and the fabricated Si-Cr precursors consist of nanocrystalline Si, CrSi2, and amorphous Si. The electrochemical analysis reveals that all ball-milled samples have a similar lithiation/delithiation mechanism with raw Si but the generation of cr-Li3.75Si can be effectively suppressed in the initial stage. The introduction of Cr can enhance cycle stability, volumetric capacity, coulombic efficiency, and electrical conductivity for Si-Cr alloys. The abnormal performance degradation phenomenon in previous Si-CuO system cannot be found here and the suggested Cr ratio is at least 15%. Furthermore, the selected Si85Cr15 precursor is conducted a carbon-coating treatment at 800 ℃, where it shows a 100- and 250-cycle capacity retention of ~93% at 0.2C and ~80% at 0.5C, respectively. The excellent cycle performance is considered related to the limited microstructure change of Si85Cr15@c-PDA due to a certain high-temperature tolerance of CrSi2 at 800 ℃. Meanwhile, it is also attributed to the synergistic effect of CrSi2 and c-PDA, with which Si85Cr15@c-PDA electrode possesses a stable structure and impedance change during the cycles.

Silicon (Si) is a promising anode material for Li-ion batteries but its application is limited due to its severe volume change during the lithiation/delithiation process, leading to a fast degradation of cycle performance. Applying transition metals to dope into the bulk Si forming active/inactive silicide phase is proved as an effective and practical method to solve the issue. However, the classic high-energy ball milling method is faced with the challenges of strict requirements to the machine, long-time working and difficulty to control the morphology of the product. Aiming to this point, the present study proposes a facile and “softer” method via coating the polydopamine (PDA) with the assistance of CuCl2·2H2O followed by a high-temperature annealing process to successfully fabricate the Si-based anode material with a unique structure of Si-Cu3Si@c-PDA. We firstly achieved the doping of Cu3Si and the coating of carbon layer simultaneously on the surface of Si. Owing to the synergistic effect of carbonized PDA layer and doped Cu3Si phase, both structural stability and electronic conductivity of electrode have been significantly enhanced. The Si-Cu3Si@c-PDA composite anode not only exhibited a high initial reversible capacity of 2356.7 mAh·g-1 with an initial coulombic efficiency of 83.6%, but also demonstrated a good capacity retention of 89.7% after 100 cycles at the current density of 400 mA·g-1. We believe this work would pave a novel way to improve the Si-based anode material.

Silicon (Si) is a promising anode material for Li-ion batteries but its application is limited due to its severe volume change during the lithiation/delithiation process leading to a fast degradation of cycle performance. Applying transition metals to dope into the bulk of Si forming active/inactive silicide phase is proved an effective and practical method to solve this issue. However, the classic high-energy ball milling method is faced with the challenges of strict requirements to the machine, long-time working and difficulty to control the morphology of the product. Aiming to this point, the present study proposes a facile and “softer” method via coating the polydopamine (PDA) with the assistance of CuCl2·2H2O followed by a high-temperature annealing process to successfully fabricate the Si-based anode material with a unique structure of Si-Cu3Si@C. We firstly achieved the doping of Cu3Si and at the same time coating the carbon layer on the surface of Si. Owing to the synergistic effect of carbonized PDA layer and doped Cu3Si phase, both structural stability and electronic conductivity of electrode have been significantly enhanced. The Si-Cu3Si@C composite anode not only exhibited a high initial reversible capacity of 2356.7 mAh·g-1 with an initial coulombic efficiency of 83.6%, but also demonstrated a good capacity retention of 89.7% after 100 cycles at the current density of 400 mA·g-1. We believe this work can pave a new way to improve the Si-based anode material.

Silicon (Si) is a promising anode material for Li-ion batteries but its application is limited due to its low electronic conductivity and severe volume change during the lithiation/delithiation process. Recently, coating a carbon layer on the Si surface and doping the alloy phase into the bulk Si have been considered as effective approaches to resolve the aforementioned issues. The present study proposes a facile method via coating the polydopamine (PDA) with the assistance of CuCl2·2H2O followed by a high-temperature annealing process to successfully fabricate the Si-based anode material with a unique structure of Si-Cu3Si@C. Owing to the synergistic effect of carbonized PDA layer and doped Cu3Si phase, both structural stability and electronic conductivity of electrode have been significantly enhanced. The Si-Cu3Si@C composite anode not only exhibited a high initial reversible capacity of 1.44 mAh·cm-2 (2483 mAh·g-1) with an initial coulombic efficiency of 83.2%, but also demonstrated a good capacity retention of 91.3% after 100 cycles at the current density of 0.28 mA·cm-2 (480 mA·g-1). In particular, an excellent reversible capacity of 0.75 mAh·cm-2 (1339 mAh·g-1) after a long-term test of 400 cycles was displayed at the high current density of 1.4 mA·cm-2 (2500 mA·g-1).