Self‐Suppression of Lithium Dendrite in All‐Solid‐State Lithium Metal Batteries with Poly(vinylidene difluoride)‐Based Solid Electrolytes

Abstract

Polymer‐based electrolytes have attracted ever‐increasing attention for all‐solid‐state lithium (Li) metal batteries due to their ionic conductivity, flexibility, and easy assembling into batteries, and are expected to overcome safety issues by replacing flammable liquid electrolytes. However, it is still a critical challenge to effectively block Li dendrite growth and improve the long‐term cycling stability of all‐solid‐state batteries with polymer electrolytes. Here, the interface between novel poly(vinylidene difluoride) (PVDF)‐based solid electrolytes and the Li anode is explored via systematical experiments in combination with first‐principles calculations, and it is found that an in situ formed nanoscale interface layer with a stable and uniform mosaic structure can suppress Li dendrite growth. Unlike the typical short‐circuiting that often occurs in most studied poly(ethylene oxide) systems, this interface layer in the PVDF‐based system causes an open‐circuiting feature at high current density and thus avoids the risk of over‐current. The effective self‐suppression of the Li dendrite observed in the PVDF–LiN(SO2F)2 (LiFSI) system enables over 2000 h cycling of repeated Li plating–stripping at 0.1 mA cm−2 and excellent cycling performance in an all‐solid‐state LiCoO2||Li cell with almost no capacity fade after 200 cycles at 0.15 mA cm−2 at 25 °C. These findings will promote the development of safe all‐solid‐state Li metal batteries.

In Situ Construction of a LiF‐Enriched Interface for Stable All‐Solid‐State Batteries and its Origin Revealed by Cryo‐TEM

“…[29][30][31][32] Moreover, the Li/ PEO interface may be continuously thickened during the battery operation originated from the repeated reactions between fresh SPE and Li (Figure 1a), resulting in large electrochemical impedance and uneven surface morphology. [27,33,34] These evolutions at the Li/PEO interface will lead to evident capacity fading with the inferior cyclability. [24,33,35] Tremendous strategies have been proposed to address the intractable issues in the Li/PEO interface, including constructing 3D matrix for Li metal, designing artificial SEI layers, and fabricating the mechanically strong SPEs.…”

Gradient‐Distributed Nucleation Seeds on Conductive Host for a Dendrite‐Free and High‐Rate Lithium Metal Anode

“…Tremendous attempts have been tried to mitigate uncontrolled lithium dendrites, mainly including: (i) improving the interface properties between electrode and electrolyte; (ii) constructing lithium‐based composites with 3D hosts. To improve the interface properties, various strategies are proposed and explored, including prefabricating artificial SEI films, precoating chemically inert protective layers, inducing additives in the electrolyte to amend SEI films, and even developing solid‐state electrolyte . Meanwhile, comparing to these attempts on stabilizing lithium anode surface, efforts on constructing lithium‐based composites with 3D hosts are superior on the reduction of local current density and bulk effect during cycling.…”

Lithium Metal Interface Modification for High‐Energy Batteries: Approaches and Characterization

“…To enhance the stability of lithium metal anodes, methods have been introduced to protect the Li metal by constructing an artificial SEI layer using an ex situ method consisted of organic or inorganic materials. [47,[172][173][174][175][176][177][178] Ex situ SEI layer formation refers to the pre-forming of an artificial SEI layer on the lithium metal surface before assembling the cell.…”

“…[36][37][38] Generally, commercial carbonate-based electrolytes are not suitable for Li metal batteries due to their high flammability and low coulombic efficiency during cycling. [36,[39][40][41] Therefore, the strategies that have been pursued to this end include modifying components of the liquid electrolyte, introducing new electrolyte systems such as solid and polymer electrolytes, [42][43][44][45][46][47][48] and adding particulate-based additives. [32,[49][50][51][52][53] Finally, Li metal interface modification is a practical approach that can be achieved using ex situ and in situ artificial layers.…”