A Novel Multielement, Multiphase, and B‐Containing SiO_x Composite as a Stable Anode Material for Li‐Ion Batteries

Abstract

In this study, a novel B‐containing SiOx composite is demonstrated with a remarkably improved cycling performance as a stable anode material for lithium‐ion batteries. A multielement, multiphase, B‐containing SiOx composite is successfully prepared by heating a mixture of SiO and LiBH4 to 500 °C. The resultant product consists mainly of amorphous/nanocrystalline Si, SiOx, B, B2O3, and Li2SiO3. The in situ formed amorphous B, B2O3, and nanocrystalline Li2SiO3 mostly remain at the surface of the product particles, providing a remarkable enhancement in the mechanical properties of the Si/SiOx active materials. This feature provides good accommodation for the volume change during lithiation/delithiation, consequently depressing the pulverization and fracture of the Si/SiOx active materials. As a result, the cycling stability of the prepared B‐containing SiOx composite is significantly improved. The sample prepared from SiO–0.3LiBH4 delivers reversible capacity of 1186 mAh g−1 at 100 mA g−1 after 100 deep cycles, corresponding to the capacity retention of 81%. This outcome is more than two times higher than that of pristine SiO (33.9%).

Green Synthesis of Dual Carbon Conductive Network-Encapsulated Hollow SiOx Spheres for Superior Lithium-Ion Batteries

“…In this context, nonstoichiometric SiO x (0 < x < 2) has drawn special interest because of its satisfactory theoretical specific capacity (2200–2500 mA h g –1 ) as well as a much better cycling performance compared to pure Si. − During the initial lithiation process, the uptake of Li by SiO x first generates a mixture of Li 2 O/Li silicates on a nanoscale, which are distributed uniformly among the formed nano-Si and act as buffer components to alleviate the huge volumetric variation during cycles. − In this regard, the compromise in specific capacity leads to the improvement in cycling stability to some extent. However, from a practical standpoint, the SiO x -based material is still insufficient to meet the market demands for long cycling life, good rate capability, and satisfactory initial coulombic efficiency (ICE) because of some intrinsic drawbacks, such as massive volumetric variation (∼200%), low electronic conductivity, and the irreversible reactions occurring during the first cycle. − Recently, through the prelithiation technology, ICE of SiO x -based anodes has been dramatically improved along with equivalent cycling performance. − Therefore, studies directed toward the improvements of cyclic and rate performances of SiO x -based materials were intensively conducted.…”

Silicon‐Based Lithium Ion Battery Systems: State‐of‐the‐Art from Half and Full Cell Viewpoint

“…[ 123–127 ] However, due to the formation of by‐products (SEI and Li 4 SiO 4 ) in the initial lithiation process, SiO x materials usually have poor ICE values and thus need to be improved. [ 99,128 ] Advanced material modification strategies provide an excellent opportunity to improve the energy densities and lifetime of SiO x ‐based full cells, thereby facilitating their practical applications. III) Benefiting from the high strength of transition metal‐Si bonds and good conductivity, transition metal‐Si materials have improved fracture resistance, and superior rate performance and lifetime in their half and full cells.…”

Sn Alloy and Graphite Addition to Enhance Initial Coulombic Efficiency and Cycling Stability of SiO Anodes for Li‐Ion Batteries

“…During heating process, B, B 2 O 3 , and Li 2 SiO 3 can formed at the surface of the product particles to depress the pulverization and fracture of the Si/SiO x active materials, leading to great cycling stability. [20] Most SiO-based anodes are hindered by the volume expansion and inferior intrinsic conductivity and require carbon to improve their cycle life. SiO/C hybrid anode materials have been studied extensively, in which the carbon serves as a conductive and buffering medium.…”

“…During heating process, B, B 2 O 3 , and Li 2 SiO 3 can formed at the surface of the product particles to depress the pulverization and fracture of the Si/SiO x active materials, leading to great cycling stability. [ 20 ]…”