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The prevalent issue of cadmium (Cd) in naturally selenium (Se)-enriched soils has significantly impacted the safe utilization of Se-rich soils. Although Se antagonizes Cd and is affected by Se:Cd stoichiometry, the mechanism behind this interaction remains unclear. To reveal the relation between the soil bioavailable Se:Cd molar ratio (AMR-Se:Cd) and the transformation of Se and Cd fractions, as well as to identify the principal controlling factors, we conducted a study in Shanggao County, Yichun City, a naturally Se-rich area in Jiangxi Province, and quantitatively analyzed the distribution features of Se, Cd, and AMR-Se:Cd across different soil types and land use types. The results demonstrated that soil AMR-Se:Cd was statistically positively correlated with the bioavailable Se content (r = 0.331, p < 0.01) and had a negative correlation with the bioavailable Cd content (r = −0.402, p < 0.001). Cd was transformed from highly bioavailable fractions to less bioavailable fractions as the AMR-Se:Cd increased. A suitable AMR-Se:Cd was conducive to achieving a higher mobility of Se (mobility factor of 12.31%) and a lower mobility of Cd (mobility factor of 23.49%) simultaneously. Spearman correlation analysis and partial least squares path modeling revealed that soil type and land use type modulated the morphological transformation of soil Se and Cd by influencing changes in free Fe-Al oxides and soil organic matter content, which in turn altered the AMR-Se:Cd. Therefore, the findings of this study can offer guidance for regulating the appropriate AMR-Se:Cd in Se-rich soils through management practices to enhance the bioavailability and mobility of soil Se while diminishing the bioavailability and mobility of Cd.

Commercial graphite anode has advantages such as low potential platform, high electronic conductivity, and abundant reserves. However, its theoretical capacity is only 372 mA h g−1. High-energy lithium-ion batteries have been a research hotspot. The Si anode has an extremely high specific capacity, but its application is hindered by defects such as large volume changes, poor electronic conductivity, and a small lithium-ion diffusion coefficient. Here, the Si/thermally reduced graphite oxide@carbon (Si/RGtO@C) composite was fabricated by electrostatic self-assembly followed by thermal treatment. The RGtO synergistic carbon coating layer can effectively compensate for the low electronic conductivity and buffer the volume expansion effect of the Si nanoparticles during charge/discharge cycles. The Si/RGtO@C anode demonstrated a significantly increased capacity compared to the RGtO. After 300 cycles, Si/RGtO@C kept a discharged capacity of 367.6 mA h g−1 at a high current density of 1.0 A g−1. The Si/RGtO@C anode shows an application potential for commercial high-energy lithium-ion batteries.