In Situ Construction of an Ultrarobust and Lithiophilic Li-Enriched Li–N Nanoshield for High-Performance Ge-Based Anode Materials

Abstract

Alloy-based materials are promising anodes for rechargeable batteries because of their higher theoretical capacities in comparison to graphite. Unfortunately, the huge volume changes during cycling cause serious structural degradation and undesired parasitic reactions with electrolytes, resulting in fragile solid-electrolyte interphase formation and serious capacity decay. This work proposes to mitigate the volume changes and suppress the interfacial reactivity of Ge anodes without sacrificing the interfacial Li + transport, through in situ construction of an ultrarobust and lithiophilic Li-enriched Li−N nanoshield, which demonstrated improved chemical, electrochemical, mechanical, and environmental stability. Therefore, it can serve as a versatile interlayer to facilitate Li + transport and effectively block the attack of electrolyte solvents, thus boosting the long-term cycle stability and fast charging capability of Ge anodes. This work offers an alternative methodology to tune the interfaces of other electrode materials as well by screening for more N-containing compounds that can react with Li + during battery operation.

In Situ Construction a Stable Protective Layer in Polymer Electrolyte for Ultralong Lifespan Solid‐State Lithium Metal Batteries

“…[ 13a,b ] As for the N 1s, the peaks around 399.1 and 402.2 eV are assigned to the N − in TFSI − and N + in IL, respectively. [ 31 ] There is an obvious change in the concentrations of the IL on the surface after cycles, while, an extra peak around 397.2 eV reveals the production of Li 3 N. [ 10,16a ] These assignments of the XPS spectra are summarized in Table S1 (Supporting Information). In addition, owing to the high sensitivity to the compound fragment information of TOF‐SIMS and MALDI‐TOF‐MS, the F − , LiF − , S − , and Li 3 N − compounds can also be detected at the PL‐SPE/Li interface after cycling (Figure S10a,b, Supporting Information).…”

“…Meanwhile, Ke et al. [ 10 ] discovered that the Li‐N artificial layer could also improve the electrochemical stability of Ge‐alloy anode materials. Recently, Tao et al.…”

Electrochemical Performance and Mechanism of Surface‐Fluorinated Fe3O4 as Stable Anode for Lithium‐Ion Batteries

“…However, the CA of FF‐2 is only 11.81° (Figure 7b), indicating that the wettability of the electrode increases with the surface modification of F. The good electrolyte wettability of FF‐2 can establish an electrolyte‐friendly interface between the electrolyte and electrode, and effectively promote the diffusion of lithium ions to the surface of the electrode. [ 41,42 ]…”

“…However, the CA of FF-2 is only 11.81 (Figure 7b), indicating that the wettability of the electrode increases with the surface modification of F. The good electrolyte wettability of FF-2 can establish an electrolyte-friendly interface between the electrolyte and electrode, and effectively promote the diffusion of lithium ions to the surface of the electrode. [41,42] Zeta (ζ) potential measurements of the different samples were carried out in a simulated electrolyte environment (pH ¼ 4). [43] As shown in Figure 7c,d, the results show that fluorination treatment leads to a more negative zeta potential on the electrode surface, which is ascribed to the prominent electronegativity of F. The enhancement of the negative electric field on the active material surface accelerates the surface adsorption and transport of lithium ions; thus, more effective interaction can occur with the electrode/electrolyte, which improves effectively the reaction kinetics of the electrode.…”

Multiscale Understanding of Surface Structural Effects on High‐Temperature Operational Resiliency of Layered Oxide Cathodes

“…In our previous works, we have used this setup to reveal the volume changes of many alloying‐based anodes during (de) lithiation. [ 29–33 ] Here we further used it to understand how PEDOT coating help mitigate the intergranular cracking of NCM811 cathode during charge/discharge.…”