In Situ Construction of a Multifunctional Interface Regulator with Amino-Modified Conjugated Diene toward High-Rate and Long-Cycle Silicon Anodes

Abstract

Silicon (Si) is deemed to be the next-generation lithium-ion battery anode. However, on account of the poor electronic conductivity of Si materials and the instability of the solid electrolyte interphase layer, the electrochemical performance of Si anodes is far from reaching the application level. In this work, a multifunctional poly­(propargylamine) (PPA) interlayer is constructed on the Si surface via a simple in situ polymerization method. Benefiting from the electronic conductivity, ionic conductivity, robust interphase interactions for hydrogen bonding, and stability of multifunctional PPA, the optimized Si@PPA-7% electrode shows improved lithium storage capability. A high capacity of 1316.3 mAh g–1 is retained after 500 cycles at 2.1 A g–1, and 2370.3 mAh g–1 can be delivered at 42 A g–1, which are in stark contrast to the unmodified Si electrode. Furthermore, the rate and cycle capabilities of the LiFePO4//Si@PPA-7% full cell are also obviously better than those of LiFePO4//Si.

Decreased Deformation and Heat as well as Improved Interface and Diffusion of Silicon To Enhance Electrochemical Performance and Safety by a Negative Thermal Expansion Material

“…According to the above results of rate performance and cyclability of various samples, 3 wt % LTP is proper to enhance the electrochemical performance of pure Si under different conditions, and the possible reasons are as follows. The electronic conductivity of the Si material is 1 × 10 −3 S/cm, 39 while the electronic conductivity of pure LTP is only 1× 10 −9 S/cm. 40 From the FESEM images in Figure 5, the particle size of LTP is bigger than that of Si.…”

Construction of a LiF-Rich and Stable SEI Film by Designing a Binary, Ion-, and Electron-Conducting Buffer Interface on the Si Surface

“…Silicon (Si) is one of the most promising anodes for the next generation of high-energy lithium-ion batteries (LIBs) due to its ultrahigh theoretical capacity (4200 mAh g –1 ), low lithiation potential (∼0.4 V), and abundant reserves . However, Si is a semiconductor, and it undergoes a volume expansion of up to 400% when Li 22 Si 5 is fully formed during charging, resulting in the fragmentation of the Si particles and continuous reorganization of the solid electrolyte interface (SEI) . The problem of poor electronic conductivity of the Si materials is usually solved by adding conductive agents, and the fragmentation of the Si particles can be alleviated by reducing the size to the nanometer level.…”

“…Therefore, stabilizing the SEI film of the Si anodes is a prerequisite for the commercialization of the Si anodes. To construct stable SEI films on the Si surfaces, many efforts have been made in terms of Si structures, − binders, − conductive agents, − and electrolyte additives. − Among various attempts, interfacial engineering to construct artificial SEI films on Si surfaces is one of the effective strategies to improve the electrochemical performance of the Si anodes. − So far, the reported interface materials include carbon coatings, − zero-strain materials, , organic small molecules, , organic polymers, , etc. In addition, there are also reports of incorporating metal particles with interfacial engineering to offer remarkable conductivity, such as decorating the surface of carbon-encapsulated Si nanoparticles with metal nanocrystals, and studies show that the incorporation of silver (Ag) nanoparticles can significantly improve charge-carrier mobility. ,, …”

“…Based on the above analysis, this work designs an Ag-decorated mucic acid (MA) buffer layer on the surface of the Si nanoparticles, and the modified Si nanoparticles are prepared as the anode and evaluated in half-cell and full cell (Figure ). The use of the MA, an organic small molecule, as the buffer interface for the Si anode, has the following advantages: first, it consists of four hydroxyl groups and two carboxyl groups, which can form hydrogen bonds and covalent bonds with hydroxyl groups on the Si surface; , second, the rich hydroxyl and carboxyl groups facilitate lithium transportation at high current densities; , third, the flexible and stable MA organic coating anchored on the Si surface counteracts the volume expansion of the Si particles; last, MA-coating layer can also form strong hydrogen bonds with the hydroxyl groups of binders. − Therefore, the stable and uniform MA coating on the Si surface guarantees the structural stability and fast lithium transport of the whole electrode, thereby improving the rate and cycle capabilities of the Si anode. Furthermore, to compensate for the poor electronic conductivity of the MA organic coating, the Ag nanoparticles are introduced by an in situ reduction reaction, , since it is the most conductive metal conductor. , Consequently, the high-rate capability and cycling stability of the Si anode are further improved.…”

In Situ Construction of S-Based Artificial Solid Electrolyte Interphases Layer for Stable Silicon Anode in Lithium-Ion Batteries

“…One approach is to regulate the composition of SEI layer via the introduction of electrolyte additives. − Jaumann et al studied the mechanisms of vinylene carbonate and fluoroethylene carbonate on the cycling and rate performance of silicon anode . The second approach is to protect the silicon surface from contact with the electrolyte. − The commonly used protective layer includes carbon, − metallic oxides, − organics, − and so on. Among them, the carbon coating can protect the surface of silicon material, but its high electronic conductivity favors the electrolyte decomposition.…”