Rational Design of the Robust Janus Shell on Silicon Anodes for High-Performance Lithium-Ion Batteries

Abstract

The high-capacity silicon anode is regarded as a promising electrode material for next-generation lithium-ion batteries. Unfortunately, its practical application is still severely hindered by electrode fracture and unstable solid electrolyte interphase during cycling. Herein, we design a structure of encapsulating silicon in a robust “janus shell”, in which an internal graphene shell with sufficient void space is used to absorb the mechanical stress induced by volume expansion, and the conformal carbon outer shell is introduced to strongly bond the loosely stacked graphene shell and simultaneously seal the nanopores on the surface. With the ultrastable janus carbon shell, the excellent structural integrity of the electrode and stable solid electrolyte interphase layer could be effectively preserved, resulting in an impressive cycling behavior. Indeed, the as-synthesized anodes demonstrate superior cycle stability and excellent rate performance, delivering a high reversible capacity of 1416 mA h g–1 at a current density of 0.2 A g–1 and 852 mA h g–1 at a high current density of 5 A g–1. Remarkably, the superior capacity retention of 88.5% could be achieved even after 400 cycles at a high current density of 2 A g–1. More importantly, this work opens up a novel avenue to address high-capacity anodes with a large volume change.

Recent Advances in Silicon‐Based Electrodes: From Fundamental Research toward Practical Applications

“…While the previously discussed nanostructures have made improvements for suppressing the huge volume expansion of Si-based materials, swelling-induced active material delamination from the current collector and electrode instability remain critical challenges for Si anodes. [262,263] In order to meet the commercial request, the tap density of Si-based electrode should reach ≈1.65 g cm −3 , while electrode swelling is limited to 10%. The concept of thickness swelling is an important factor for electrode design and is usually ignored for material design.…”

Enhanced Cycle Stability of Crumpled Graphene-Encapsulated Silicon Anodes via Polydopamine Sealing

“…Compared to other Si/C anodes prepared based on the same spray-drying technique ( Table S2 ), cpDOPA-crGO–Si displays competitive capacity and improved cycling stability with a simple and efficient production process. Although Yan et al 68 very recently conducted a similar pDOPA coating method, our material exhibits better cycle life and uses much less electrolyte additives [5% FEC vs 10% FEC and 2% vinylene carbonate (VC)], which is attributed to the optimization of spray-drying parameters.…”

Scalable Synthesis of Porous SiFe@C Composite with Excellent Lithium Storage

“…The peak between 0.5–1.0 V corresponds to the irreversible formation of the SEI film, [44] and in the subsequent cycles this peak gradually disappears. In the first cathodic sweep process, the peak below 0.1 V is ascribed to the formation of amorphous Li x Si by intercalation of lithium ions into crystalline silicon [45] . In the subsequent cycles, silicon remains amorphous all the time, and the cathodic peak is stable at about 0.16–0.18 V. The two peaks located at about 0.35 and 0.52 V are attributed to the dealloying of Li x Si back to amorphous silicon [46, 47] in the corresponding anodic scan.…”