Differentiated Lithium Salt Design for Multilayered PEO Electrolyte Enables a High‐Voltage Solid‐State Lithium Metal Battery

Abstract

Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high‐energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO‐based solid polymer electrolyte (DSM‐SPE) is exploited to achieve excellent electrochemical performance toward both the high‐voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM‐SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high‐voltage (≥4.3 V) LiCoO2/Li metal battery with PEO‐based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm−2 (0.25 mAh cm−2). Even under a high‐area capacity of 2 mAh cm−2, the profiles still maintain stable. The pouch cell with DSM‐SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM‐SPE‐based lithium metal battery.

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.…”

“…[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. [36][37][38][39] Of note, LiF is found as an excellent interfacial component which possesses low Li ions diffusion barrier and superior electronic insulation, thus facilitating the Li ions transfer and homogeneous Li deposits in the batteries with liquid electrolyte.…”

Enabling a Durable Electrochemical Interface via an Artificial Amorphous Cathode Electrolyte Interphase for Hybrid Solid/Liquid Lithium‐Metal Batteries

“…Fortunately, the above drawbacks can be significantly conquered when an amorphous cathode electrolyte interphase (CEI) has been in situ deposited at the interface, owing to its excellent structure compatibility and plasticity . However, there is still a lack of systematic studies on how the amorphous CEI manipulates the cathode interface in a hybrid solid/liquid battery system . Thus, it is of great significance to elaborate an amorphous buffer layer via an in situ conversion reaction, and further expound the interfacial stability mechanism in a system closer to practical application.…”

“…[11][12][13] However, there is still a lack of systematic studies on how the amorphous CEI manipulates the cathode interface in a hybrid solid/liquid battery system. [14] Thus, it is of great significance to elaborate an amorphous buffer layer via an in situ conversion reaction, and further expound the interfacial stability mechanism in a system closer to practical application.…”

Recent Progress of Electrolyte Design for Lithium Metal Batteries

“…However, long‐standing bottlenecks still maintain, such as inadequate ionic conductivity, poor oxidative stability and undesired side reactions with lithium anode, deteriorating its large‐scale commercialization. Recently, Cui's group demonstrated a multilayer structure of PEO‐based electrolyte to tackle these tough issues . They chose succinonitrile (SN) as the effective plasticizer and combined it with PEO polymer, delivering favorable ionic conductivity by destructing the internal crystallization.…”