Energy Storage System

(1) Battery Engineering

1-1) Artificial interfacial protective layer for Lithium metal anodes

Reference: Seung Ho Shin†, Seungjae Gwak† (Co-First author), and Jae Young Seok, "Scalable, Multi-Functional Nano-Silicon Composite Protective Interlayer to Suppress the Formation of Lithium Dendrites for Stabilizing Lithium Metal Anodes", Energy Technology, (https://doi.org/10.1002/ente.202502212)

■ Background (Why important?)

• As the demand for next-generation energy infrastructure continues to grow, the need for energy storage systems with higher energy density, improved safety, and longer lifespan has become increasingly urgent. Lithium-ion batteries (LIBs) have led the market for decades but are now approaching theoretical capacity limits (i.e., 372 mAh/g especially for graphite anode). In this context, lithium metal batteries (LMBs) have emerged as a promising alternative, offering a high theoretical specific capacity (3860 mAh/g) and a very low electrochemical potential (−3.04 V versus the standard hydrogen electrode). However, critical challenges such as lithium dendrite growth (Figure a) still hinder their practical application.

■ Resluts (My contributions)

• Designed a slurry-coated composite protective layer for Li-Metal Anode, composed of Si nanoparticles, Super C45 (Carbon black), and PVDF-HFP (Fluoropolymer-based binder), targeting a mixed ionic–electronic conductive (MIEC) interlayer (Electrode name: Si-NPs/Super C45). Additionally, we identified optimal conditions for interfacial transport and mechanical stability through a parameter study of the composition mass ratio and interlayer thickness. Figure b and Figure c show "Fabrication procedures" and "Working principles" of interfacial protective layer for LMBs, respectively. 

• Symmetric cell performance [Li||Li]: 

Figure d: Tafel plots show a fivefold increase in exchange current density compared to bare lithium, indicating improved interfacial kinetics. / Figures e and Figures f: Nyquist plots obtained from Electrochemical Impedance Spectroscopy (EIS) illustrate lower charge-transfer resistance, demonstrating enhanced long-term cell stability. / Figure g: Scanning Electron Microscope (SEM) top view images of the electrode after 50 cycle at the current density of 1 mA/cm² reveal that Si-NPs/Super C45 has no macroscopic cracks and accommodates significant volumetric changes during cycling.

• Full cell performance with LiFePO₄ (LFP) cathode [Li||LFP]:

Figure h-1: Si-NPs/Super C45 delivers stable cycling in an LFP full cell at 0.5C (after 3 formation cycles at 0.2C), achieving 97.8% capacity retention over 150 cycles with an average CE of 99.9%. / Figure h-2: Si-NPs/Super C45 maintains a stable voltage profile from the 5th (solid) to the 150th (dashed) cycle, indicating suppressed hysteresis growth and mitigated capacity fading compared with bare Li. / Figure h-3: Si-NPs/Super C45 shows lower interfacial impedance in the Nyquist plot after 10 cycles, consistent with a more stable Li|electrolyte interface.

• Research significance: This fabrication process uses standard slurry preparation, blade-coating, and rolling operations and is directly compatible with roll-to-roll (R2R) manufacturing, enabling immediate translation to existing battery production lines. Compared to previous studies, this fabrication process is significantly simpler, requiring no complex synthesis or post-treatment steps for protective layer formation. Moreover, while prior works have primarily investigated MIEC characteristics under solid-state electrolytes, our study extended the analysis to liquid-electrolyte systems.