The Role of Polymer and Inorganic Coatings to Enhance Interparticle Connections Diagnosed by In Situ Techniques

Abstract

Surface coating on alloy anodes renders an effective remedy to tolerate internal stress and alleviate the side reaction with electrolytes for long-lasting reversible lithium redox reactions in lithium-ion batteries. However, the role of surface coating on the interparticle connections of alloy anodes remains not fully understood. Herein, we exploit real-time lithiation and mechanic measurement of SnO2 nanoparticles via in situ TEM with different coating layers, including conducting polymer polypyrrole and metal oxide MnO2. As a result, polypyrrole is more flexible to accommodate the volume expansion issue. More importantly, the polypyrrole coating layers offer a large contact area and strong adhesion force between the SnO2 nanoparticles, ensuring fast lithiation kinetics and high cycling stability. These observations provide new insight into how the interparticle connections of alloy anodes with diverse coating approaches can impact battery performance, shedding light on the practical processing of the alloy anode materials for high-energy Li-ion batteries.

Polypyrrole-Wrapped SnS2 Vertical Nanosheet Arrays Grown on Three-Dimensional Nitrogen-Doped Porous Graphene for High-Performance Lithium and Sodium Storage

“…The PPy shell exhibits mechanical strength and flexibility to withstand the internal stress of the active material, and the shell does not break during the entire cycling test. 62 The PPy shell also firmly fixes the active material, increases the strength of the connection between active materials, prevents the separation of active materials, and maintains the integrity of the electrode well after many expansion/contraction cycles. What is more, the PPy layer provides more transport paths for electrons and ions, enhancing ion diffusion and electron transport.…”

“…The interaction of the PPy layer and the active material has been further investigated in some reported works, , in which in situ transmission electron microscopy shows that the volume expansion of the active material with the PPy coating is lower than that of the active material with an inorganic semiconductor coating. The high stability provided by the PPy coating is attributed to its flexibility.…”

“…The high stability provided by the PPy coating is attributed to its flexibility. The PPy shell exhibits mechanical strength and flexibility to withstand the internal stress of the active material, and the shell does not break during the entire cycling test . The PPy shell also firmly fixes the active material, increases the strength of the connection between active materials, prevents the separation of active materials, and maintains the integrity of the electrode well after many expansion/contraction cycles.…”

Lithiated Hybrid Polymer/Inorganic PAA/MnO2 Protection Layer for High-Performance Tin Oxide Alloy Anode

“…The mass ratio of SnO 2 /MnO 2 is evaluated to be 7:1 determined by energy-dispersive X-ray spectroscopy (EDS) (Figure S1). For fair comparison, SnO 2 @MnO 2 NPs without PAA were prepared by generally reducing KMnO 4 on the surface of SnO 2 via carbon serves as a sacrificial template, according to the reported method. ,, Figure S2 shows the TEM image of the SnO 2 @MnO 2 NPs with random MnO 2 nanosheets observed. X-ray diffraction (XRD) measurements were performed to verify the crystalline structures of SnO 2 @PAA/MnO 2 and SnO 2 @MnO 2 .…”

Using Single-Crystal Graphene to Form Arrays of Nanocapsules Enabling the Observation of Light Elements in Liquid Cell Transmission Electron Microscopy

“…Transmission electron microscopy (TEM) using a special liquid container has emerged as a powerful tool for observing the physical phenomena occurring in nanoscale liquids. This technique has provided information on the dynamics of a variety of interactions among liquid, gas, and solid phases in real time such as the nucleation, growth, and movement of nanoparticles and bubbles. − To date, silicon nitride (Si 3 N 4– x ) liquid cells have been widely used since the Si 3 N 4– x material is moderately transparent to the electron beam (e-beam) of a TEM, allowing direct observation of a specimen immersed in a nanoliter of liquid. The rigid Si 3 N 4– x membranes have also offered a platform for experiments conducted under flow, heating, and/or electrical bias. − However, the use of a relatively thick Si 3 N 4– x window and the presence of the spacer material positioned between two Si 3 N 4– x windows cause significant inelastic scattering of the incident e-beam in the window and liquid layer, and it has not been possible to obtain high-resolution images of low- Z materials …”