In Situ Developed Si@Polymethyl Methacrylate Capsule as a Li-Ion Battery Anode with High-Rate and Long Cycle-Life

Abstract

The development of Si-based lithium-ion batteries is restricted by the large volume expansion of Si materials and the unstable solid electrolyte interface film. Herein, a novel Si capsule with in situ developed polymethyl methacrylate (PMMA) shell is prepared via microemulsion polymerization, in which PMMA has high lithium conductivity, high elasticity, certain viscosity in electrolytes, as well as good electrolyte retention ability. Taking advantage of the microcapsule structure with the PMMA capsid, the novel Si capsule anode retains 1.2 mA h/cm 2 at a current density of 2 A/g after 200 electrochemical cycles and delivers higher than 66% of its initial capacity at 42 A/g.

Emerging Organic Surface Chemistry for Si Anodes in Lithium‐Ion Batteries: Advances, Prospects, and Beyond

“…As shown in Figure 4 a, Yin and Sun et al. [ 49b ] reported an MLD zincone coating on the Si electrode adopting the self‐limiting reaction between ethylene glycol and diethylzinc. The zincone layer is an inorganic–organic hybrid film the thickness of which can be easily controlled by the number of MLD reaction cycles (10, 25, and 50 cycles respectively).…”

“…We note that other MLD‐grown organic coating like alucone [ 92 ] and titanicone [ 93 ] demonstrate superior Li‐ion conductance than ALD‐grown inorganic films. One direct sign is that the 15 nm‐thick zincone coatings (50 MLD cycles) allow facile Li cycling of the underneath Si [ 49b ] while 4 nm‐thick ALD‐Al 2 O 3 completely blocks Li‐ion flux and deactivate the Si particles. [ 57a ]…”

Bioinspired Thermal Runaway Retardant Capsules for Improved Safety and Electrochemical Performance in Lithium‐Ion Batteries

“…Note that the main difference between the microcapsule materials mentioned in this work and core-shell structure battery materials is that the microcapsule shell will be destroyed when the cell fails, and its function is mainly to release the core material to avoid accidents, such as fire, or realize the healing of specific functions of the cell, such as electrical conductivity; however, the shell of the core-shell material will not be damaged (i.e., there is no releasing process), and its function is to improve certain defects of core materials faced by Si-based LIBs, such as large volume expansion of Si materials and the unstable SEI layers. [54] In summary, capsule technology has broad application prospects in the battery field. In addition to prolonging cycling life and improving reliability it can also be used to improve battery safety.…”

A Novel Tin-Bonded Silicon Anode for Lithium-Ion Batteries

“…0.4 V vs Li/Li + , and high terrestrial abundance. 4,5 However, low cyclic stability, low rate performance, and low initial Coulombic efficiency (ICE) caused by the large volume change of the Si anode during cycling, a low intrinsic electronic conductivity, and the repetitive formation of an unstable solid electrolyte interphase (SEI) caused by the severe side reactions of Si with electrolytes are the three major drawbacks hindering the commercialization of Si-based anodes. 6−10 To tackle these issues, addressable strategies have been proposed.…”

“…Among various anode materials, silicon (Si) is regarded as a promising candidate to replace the traditional commercial graphite anodes for LIBs owing to its advantages of high theoretical specific capacity of 3579 mAh g –1 for Li 15 Si 4 , low potential of ca. 0.4 V vs Li/Li + , and high terrestrial abundance. , However, low cyclic stability, low rate performance, and low initial Coulombic efficiency (ICE) caused by the large volume change of the Si anode during cycling, a low intrinsic electronic conductivity, and the repetitive formation of an unstable solid electrolyte interphase (SEI) caused by the severe side reactions of Si with electrolytes are the three major drawbacks hindering the commercialization of Si-based anodes. − …”