Robust Transport: An Artificial Solid Electrolyte Interphase Design for Anode‐Free Lithium‐Metal Batteries

Abstract

One of the most challenging issues in the practical implementation of high‐energy‐density anode‐free lithium‐metal batteries (AFLMBs) is the sharp capacity attenuation caused by the mechanical degradation of the solid electrolyte interphase (SEI). However, developing an artificial SEI to address this issue remains a challenge due to the trade‐off between ionic conductivity and mechanical robustness for general ionic conducting films. In this study, a tenacious composite artificial SEI with integrated heterostructure of lithium fluoride (LiF) and lithium phosphorus oxynitride (LiPON) is prepared using a co‐sputtering approach to achieve both high ionic conductivity and fracture toughness. The embedded LiF domain has an extremely high Young's modulus and surface energy compared with those of bulk LiPON film, enabling a significant increase in fracture toughness by an order of magnitude. Most importantly, the interface between LiPON and LiF in the integrated structure generates additional fast Li+‐transport pathways, providing the artificial SEI with a conductivity higher than 10−6S cm−1. Consequently, the artificial SEI implementation significantly increases the cycling lifetime of the corresponding AFLMBs by >250%. This study highlights the importance of fracture toughness for the structural integrity of batteries and provides suggestions for designing viable SEI materials for high‐performance AFLMBs.

Energy-dense anode-free rechargeable lithium metal batteries based on thick cathodes and pulse charging strategies

“…[39][40][41][42][43][44][45] Therefore, using Cu‖5LFP batteries, we attempt to improve the performance of AFLMBs using different pulse charging methods. On the basis of the same total charging time as 0.5 mA cm −2 , two types of charging protocols are designed, including periodically charging at 0.75 mA cm −2 for 2 s and resting for 1 s (named pc2,1), and periodically charging at 1 mA cm −2 for 1 s [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60] and resting for 1 s (named as pc1,1). Fig.…”

“…(g) Electrochemical impedance spectroscopy (EIS) of Cu‖5LFP batteries in the conventional or pulse charge (pc1,1) process. (h) Electrochemical performance comparisons of Cu‖LFP AFLMBs [46][47][48][49][50][51][52][53][54][55][56][58][59][60]…”

Understanding SEI evolution during the cycling test of anode-free lithium-metal batteries with LiDFOB salt

“…[6][7][8] In particular, interfacial reactions that form the solid electrolyte interphase (SEI) layer consume the active Li and adversely affect the AFLMBs cell life. 9,10 The undesirable heterogeneous SEI layer may form due to inherent electrolyte instability at low reduction potentials and inhomogeneous surface chemistry. This passivation layer produces unequal electric eld distribution and Li concentration gradient, which may be the root cause of Li dendrites growth.…”

Scalable fabrication of ultra-fine lithiophilic nanoparticles encapsulated in soft buffered hosts for long-life anode-free Li2S-based cells

“…This strategy eliminates the use of metallic Li anodes, maximizing the energy density and lowering cell production costs. 12,15 Many research studies have evaluated the feasibility of AFCs, [16][17][18] with Zhang's and Dahn's groups achieving significant efficiency and cycle life for Cu||LiFePO 4 and Cu|| LiNi 0.5 Mn 0.3 Co 0.2 O 2 cells. 19,20 Compared with these intercalationtype cathodes (<300 mA h g −1 ), conversion-type Li 2 S cathodes provide a much higher theoretical capacity (1167 mA h g −1 ), corresponding to a high energy density of 2451 W h kg −1 with an anode-free configuration (Fig.…”