Interface Engineering to Boost Thermal Safety of Microsized Silicon Anodes in Lithium‐Ion Batteries

Abstract

efforts have been made to design unique Si nanostructures or construct elaborate SEIs to address the reversibility issues of Si-based anodes. [4] Despite these advances, ensuring the safe operation of Si anodes is still challenging, which impedes commercialization. In addition, the uncontrolled breakdown of the SEI will accelerate capacity fading, resulting in safety hazards, especially under harsh conditions. [5] As a low-cost alternative, low-grade microsized Si particles promise practical industrial-scale applications, but they may be more prone to failure. [6] Therefore, exploring the comprehensive thermochemical/electrochemical/mechanical behaviors of microsized Si anodes is essential for guiding the design strategies for safe, high-energy LIBs.In general, the thermal runaway process in LIBs includes three main stages: the pre-stage, heat accumulation stage, and thermal runaway stage. [7] Reversible heat (Q r ), polarization heat (Q p ), and side reaction heat (Q s ) are generated as a result of a series of reversible and irreversible electrochemical/chemical reactions. [8] Owing to the positive feedback loop from the heat-temperature-reaction, heat generated in the cells will increase the temperature and accelerate the exothermic reactions. Furthermore, the intrinsic nature of the SEI has shown to be closely related to cell performance (e.g., reversible capacity, rate capability, low/high-temperature performance, self-discharging, and safety). [9] The initial breakdown of the SEI occurs at the onset temperature of the self-heating stage, which usually depends on the SEI component/structure, and causes the cell to continue heating up. [1c] Regulating SEI formation on the anode surface has proven to be effective in postponing or preventing the thermal failure of batteries. [10] Nevertheless, microsized Si particles pose a much more significant challenge owing to the high mechanical stress during cycling. An investigation into the interplay between SEI and the thermal safety of microsized Si anodes is still lacking, especially one that combines thermal runaway analysis.In this work, we demonstrate reversibly cycled, thermally stable microsized Si anodes boosted by the construction of a robust SEI, where a moderate-concentration ionic-liquid (IL) electrolyte of lithium bis(fluorosulfonyl)amide (LiFSI, 2 m) in N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide (Pyr 14 FSI) is utilized. The synergistic effects of SEI on the Battery safety is vital to the application of lithium-ion batteries (LIBs), especially for high energy density cells applied in electric vehicles. As an anode material with high theoretical capacity and natural abundance, Si has received extensive attention for LIBs. However, it suffers from severe electrode pulverization during cycling due to large volume changes and an unstable solid electrolyte interphase (SEI), resulting in accelerated capacity fading and even safety hazards. Therefore, safe and long-term cycling of Si-based anodes, especially under high-temperature cycling, is...

Microstructure Engineered Silicon Alloy Anodes for Lithium‐Ion Batteries: Advances and Challenges

“…However, this strategy may also result in increased surface areas and, thereby, low initial CEs and irreversible capacity loss. [154,155] Other effective measures have been applied to enhance Si anodes' safety, such as developing new binders [156] and electrolytes. [157,158] Overall, achieving large-scale production, multifunctional composites, and good safety is vital to make further breakthroughs in commercialization of Si-based alloy anodes for next-generation high-energy secondary batteries.…”

“…Microstructure engineering can alleviate the volume expansion of Si‐based anodes, for instance, nanostructure and porous structure design. However, this strategy may also result in increased surface areas and, thereby, low initial CEs and irreversible capacity loss [154,155] . Other effective measures have been applied to enhance Si anodes’ safety, such as developing new binders [156] and electrolytes [157,158] …”

The pursuit of commercial silicon-based microparticle anodes for advanced lithium-ion batteries: A review

“…When the SiMP anode is employed, the huge volume changes bring more severe challenges of safety at high temperatures. Very recently, Hu's group demonstrated the thermochemical behavior and thermal safety of SEIs on SiMP anodes for high-energy LIBs [169]. The employment of a moderate-concentration IL-based electrolyte, which is compatible with SiMP anodes, is favorable for the formation of robust SEIs with thermally stable, highmodulus, and inorganic-rich features (Fig.…”

Practical production of heteroatom-bridged and mixed amorphous–crystalline silicon for stable and fast-charging batteries

“…11,12 However, the commercial application of Si as the active material has been restrained due to a huge volume change during lithiation/delithiation (>300%), subsequently leading to severe pulverization, electroactive material loss, and nally rapid capacity decay. 13,14 Therefore, pure Si cannot sustain its high gravimetric and volumetric capacity during its cycle life, hardly replacing conventional graphite anodes up to now. In this regard, many researchers have focused on maximizing the above-mentioned advantages and intrinsic features of Si anodes at both the electroactive and electrode levels to achieve high energy density and stable cycle retention.…”