Preparation and electrochemical performance of a porous polymer-derived silicon carbonitride anode by hydrofluoric acid etching for lithium ion batteries

Abstract

Porous silicon carbonitride (SiCN) ceramics were pyrolyzed from poly(silylcarbondiimide) derivatives, followed by etching with different concentrations of HF aqueous solution (5, 10, 15 and 20 wt%). The morphologies, structures and electrochemical performances of the HF-etched SiCN materials were investigated. The results indicated that the surface of the HF-etched SiCN composites became rough and porous. SiCN-10-HF, one of four HF-etched SiCN samples, showed excellent electrochemical properties as an anode for lithium ion batteries. Charge-discharge measurements indicated that the SiCN-10-HF anode exhibited a high initial specific discharge capacity of 681 mA h g À1 at a current density of 40 mA g À1 , which was 2.4 times that of the unetched SiCN anode. After 100 cycles, the discharge capacity of SiCN-10-HF anode delivered 229.3 mA h g À1 , which was 5.0 times that of the unetched SiCN anode (45.6 mA h g À1 ). Additionally, the SiCN-10-HF anode exhibited high rate performance. At a current density of 190 mA g À1 , the discharge capacity of the anode was 160 mA h g À1 .It was deduced that the formation of nano-sized pores or holes on the surface of the SiCN materials in the HF-etching process not only offered new channels for the intercalation of Li + but also relieved the volume expansion during the charge and discharge process, resulting in improved capacity, stable cycling and good rate capability.

Pressure‐Induced Vapor Synthesis of Carbon‐Encapsulated SiOx/C Composite Spheres with Optimized Composition for Long‐Life, High‐Rate, and High‐Areal‐Capacity Lithium‐Ion Battery Anodes

“…The O 1s peaks ranging from 532.91 to 532.37 eV may arise from the overlapping of Si—O—Si, C—O—Si, and C—O—C peaks . The C 1s peak of elemental carbon has been reported in the range of 284–285 eV . Therefore, the C 1s peaks ranging from 284.78 to 284.16 eV manifest that C exists mainly in the form of elemental carbon for the aforementioned five SiO x /C samples.…”

Polymer-Derived and Sodium Hydroxide-Treated Silicon Carbonitride Material as Anodes for High Electrochemical Performance Li-ion Batteries

“…The smaller semicircle for SiCN‐0.5‐NaOH anode indicates a lower electrochemical resistance than untreated SiCN anode . The results were fitted to an electrochemical model using ZView module from Sai software set. The fitting model is an equivalent circuit electrochemical model, which is depicted, in the inserted figure of Figure .…”

“…The process of our NaOH‐treating for SiCN materials involves no highly toxic chemical reagent and it is easy to operate for practical use. Compared with HF‐treating for porous SiCN which we have done before, our NaOH‐treating is safer and more environmental‐friendly, and even the electrochemical performance of NaOH‐treating SiCN is better than HF‐treating one. Therefore, our treating method for micro‐cracked or porous SiCN materials can be generalized to other Si‐based material anodes for the application of Li‐ion batteries.…”

“…Hence, in this paper, we focus on the preparation of micro‐cracked SiCN materials without Si 3 N 4 phase by carbon‐rich polymer precursor via chemical synthesis. In our previous research, we found that hydrofluoric acid can react with Si 3 N 4 phase by etching SiCN matrix, leading to enhanced capacity and cycle stability . However, the hydrofluoric acid is toxic and harmful to the environment.…”

“…As one of alternative anode materials, polymer‐derived silicon carbonitrides (SiCN) have been studied in the middle of 1990s, and a rebirth of research boom is being spurred since 2006 . They are prepared by the controlled pyrolysis of inorganic‐organic hybrid polymers containing Si, H, C and N in an inert atmosphere at relatively low temperatures .…”