Phosphonium Bromides Regulating Solid Electrolyte Interphase Components and Optimizing Solvation Sheath Structure for Suppressing Lithium Dendrite Growth

Abstract

Electrolyte additives play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long‐life lithium metal batteries (LMBs), however, it is still challenging to design individual additive for adjusting the solid electrolyte interphase (SEI) components and changing lithium ion solvation sheath in the electrolyte at the same time for optimizing electrochemical performance. Herein, alkyl‐triphenyl‐phosphonium bromides (alkyl‐TPPB) are designed as the electrolyte additive to enhance the stability of metallic Li anode under the guidance of multi‐factor principle for electrolyte additive molecule design (EDMD). Both alkyl‐TPP cations and Br− anions produce positive influences on suppressing Li dendrite growth and stabilizing the unstable interphase between metallic Li anode/electrolyte. As expected, the optimized solvation sheath structure, and the stable SEI suppress Li dendrite growth. As a result, the Li||Li4Ti5O12 cell reveals a long stable life over 1000 cycles with high Coulombic efficiency (99.9%). This work provides an insight on stabilizing SEI and optimizing solvation sheath structure with novel approach to develop long‐term stability and safety LMBs.

Optimizing Electrode/Electrolyte Interphases and Li‐Ion Flux/Solvation for Lithium‐Metal Batteries with Qua‐Functional Heptafluorobutyric Anhydride

“…There was no additional oxidation peak in the HFAcontained electrolyte, which could verify the stability of the electrolyte. [9] Figure S8c and S8d show the first three chargedischarge curves in the blank and HFA-contained electrolytes, respectively. The discharge specific capacity of Li k NCM622 full cell with HFA increases to 169 mAh g À1 , while there is only 160 mAh g À1 in the blank electrolyte.…”

“…Until now, some helpful strategies are reported to inhibit the Li-dendrite growth and stabilize the electrolyte/electrode interface, i.e., electrolyte modification, [8,9] solid-state electrolytes, [10] high-concentration electrolytes and localized highconcentration electrolytes, [11][12][13] ionic liquids, [14,15] structural design of anode materials, [16] special charging methods, [17] etc.…”

CuCl2‐Modified Lithium Metal Anode via Dynamic Protection Mechanisms for Dendrite‐Free Long‐Life Charging/Discharge Processes

“…[ 32 ] In the fitted spectrum of P, the peak at 137.21 eV ascribed to the PF bond and the peak at 134.02 eV stemming from the LiP bond. [ 33 ] The attached electrolyte was carefully washed off from the lithium foil used for the tests, so the peaks of these bonds should originate from the complex composition of the SEI. To conclude, the simultaneous morphology and composition evolution of the protective layer of CuCl 2 /Li is illustrated in Figure 4i.…”

Porous MOFs–Zinc Cobaltite/Carbon Composite Nanofibers for High Lithium Storage

“…[12][13][14] Besides, severe pulverization of the ZnCo 2 O 4 structure with large volume changes usually occurs in host materials during the lithium insertion/release process, which leads to aggregation of particles and accumulation of solid-electrolyte interphase (SEI) layers on the surface and consequently resulting in rapid capacity fading. [15][16][17][18] In previous results, it was found that the stability of ZnCo 2 O 4 could be greatly improved by modifying it with 2D or 3D nanostructures such as coordination polymers, fibrotic metal, and metal-organic frameworks (MOFs). [19,20] Among them, MOF materials are more attractive due to their high surface areas and multiple metal active sites.…”