High‐Performance Microsized Si Anodes for Lithium‐Ion Batteries: Insights into the Polymer Configuration Conversion Mechanism

Abstract

Microsized silicon particles are desirable Si anodes because of their low price and abundant sources. However, it is challenging to achieve stable electrochemical performances using a traditional microsized silicon anode due to the poor electrical conductivity, serious volume expansion, and unstable solid electrolyte interface. Herein, a composite microsized Si anode is designed and synthesized by constructing a unique polymer, poly(hexaazatrinaphthalene) (PHATN), at a Si/C surface (PCSi). The Li+ transport mechanism of the PCSi is elucidated by using in situ characterization and theoretical simulation. During the lithiation of the PCSi anode, CN groups with high electron density in the PHATN first coordinate Li+ to form CNLi bonds on both sides of the PHATN molecule plane. Consequently, the original benzene rings in the PHATN become active centers to accept lithium and form stable Li‐rich PHATN coatings. PHATN molecules expand due to the change of molecular configuration during the consecutive lithiation process, which provides controllable space for the volume expansion of the Si particles. The PCSi composite anode exhibits a specific capacity of 1129.6 mAh g−1 after 500 cycles at 1 A g−1, and exhibits compelling rate performance, maintaining 417.9 mAh g−1 at 16.5 A g−1.

Ultrastable Three-Dimensional Triptycene- and Tetraphenylethene-Conjugated Microporous Polymers for Energy Storage

“…Increasing energy consumption and climate damage from the use of conventional fossil fuels are spurring the development of alternative energy sources and efficient energy storage devices. In particular, supercapacitors have become attractive devices because of their rapid charge/discharge switching, high power density, and long cycle life. − The storage of electrical charge in supercapacitors arises from their functioning as electrochemical pseudocapacitors or electrical double-layer capacitors (EDLCs). − Charge storage in pseudocapacitors, also known as redox supercapacitors, operates through reversible redox reactions occurring between the electrolyte and electrode materials. − In EDLCs, charge storage is more of a physical process, involving adsorption/desorption of charged ions at the interface between the electrolyte and the electrode; accordingly, EDLCs require a high surface area, a narrow and consistent pore size distribution, and a large pore volume if they are to provide high capacitance. , Porous organic polymers (POPs) are interesting materials because of their potential for application in various fieldsespecially for energy storage and gas capture. − According to IUPAC classification, porous materials can be divided into macroporous (pore diameter: >50 nm), mesoporous (2–50 nm), or microporous (<2 nm). POPs can also be defined in terms of their synthetic materials and their methods of constructed routes, for example, as covalent organic frameworks (COFs), covalent triazine frameworks (CTFs), hyper-crosslinked polymers (HCPs), and conjugated microporous polymers (CMPs). − CMPs are particularly interesting because they are amorphous materials possessing linked π-conjugated building blocks, where the sizes of the linkers can range from small phenyl units to bicyclic and macrocyclic moieties.…”

Scalable Fabrication of Silicon‐Graphite Microsphere by Mechanical Processing for Lithium‐Ion Battery Anode with Large Capacity and High Cycling Stability

“…[4,5] However, silicon anode suffers from the huge volume expansion (4 00 %) during lithiation, structural collapse caused by the delithiation and poor electrical conductivity, thus, the poor electrochemical performance of which hinders the commercial application. [6,7] In order to solve the above problems, numerous strategies have been developed. Nano-sized silicon, like silicon nanowires, [8] nanotubes, [9,10] nanoparticles, [11] perform increased cycle life of battery due to the reduced mechanical fracture of Si.…”

Constructing a Yolk–Shell Structure SiOx/C@C Composite for Long-Life Lithium-Ion Batteries

“…Energy depletion and environmental pollution have gradually become major problems that cannot be ignored in today’s world, while the pursuit of sustainable development is meaningful. − At present, consumers focus on green new energy storage technologies and devices represented by lithium-ion batteries (LIBs), which are usually used in 3C electronics on account of their advantages of high operating voltage, long service life, and environmental friendliness. − Conventional commercial LIBs based on graphite anodes are unable to match the need for high energy density, which suffer from limited theoretical specific capacity (372 mAh g –1 ). − On this basis, silicon-based anodes have become the most potential substitute for commercial graphite anodes in the future because of their high theoretical specific capacity (∼4200 mAh g –1 ) and suitable operating voltage (<0.5 V vs Li/Li + ). , Nevertheless, the enormous volume changes of silicon materials in repeated galvanostatic discharge/charge processes lead to the rapid attenuation of capacity and even cause safety problems, which seriously restricts the commercial application of silicon-based LIBs. , In addition, silicon-based materials are a common semiconductor material which has poor electrical conductivity. Therefore, improving the conductivity of silicon electrodes is necessary even if this strategy may offset the superiority of high capacity. , …”