Facilitating Interfacial Stability Via Bilayer Heterostructure Solid Electrolyte Toward High‐energy, Safe and Adaptable Lithium Batteries

Abstract

Solid‐state electrolytes are widely anticipated to enable the revival of high energy density and safe metallic Li batteries, however, their lower ionic conductivity at room temperature, stiff interfacial contact, and severe polarization during cycling continue to pose challenges in practical applications. Herein, a dual‐composite concept is applied to the design of a bilayer heterostructure solid electrolyte composed of Li+ conductive garnet nanowires (Li6.75La3Zr1.75Nb0.25O12)/polyvinylidene fluoride‐co‐hexafluoropropylene (PVDF‐HFP) as a tough matrix and modified metal organic framework particles/polyethylene oxide/PVDF‐HFP as an interfacial gel. The integral ionic conductivity of the solid electrolyte reaches 2.0 × 10−4 S cm−1 at room temperature. In addition, a chemically/electrochemically stable interface is rapidly formed, and Li dendrites are well restrained by a robust inorganic shield and matrix. As a result, steady Li plating/stripping for more than 1700 h at 0.25 mA cm−2 is achieved. Solid‐state batteries using this bilayer heterostructure solid electrolyte deliver promising battery performance (efficient capacity output and cycling stability) at ambient temperature (25 °C). Moreover, the pouch cells exhibit considerable flexibility in service and unexpected endurance under a series of extreme abuse tests including hitting with a nail, burning, immersion under water, and freezing in liquid nitrogen.

Double-Layer Solid Composite Electrolytes Enabling Improved Room-Temperature Cycling Performance for High-Voltage Lithium Metal Batteries

“…28,42 The interface stability of these electrolyte membranes against the lithium anode during the lithium stripping/plating process is investigated through a galvanostatic polarization measurement on lithium symmetric cells at the current density of 0.1 mA cm −2 (Figure 4). Consistent with the literature, 15,33 the PVDF SPEs always show a fairly poor electrochemical stability toward lithium metal, with a sharp voltage increase of the Li|PVDF|Li cell after only cycling for 65 h (Figure 4a). With the introduction of PEO, the blending (PEO+PVDF) SPEs can exhibit a reinforced contact between the electrolyte and lithium anode for decreased interface resistance, 35 which thus delivers a lower initial overpotential and a slightly improved stripping/plating cycling (Figure 4b).…”

“…29,30 By contrast, poly(vinylidene fluoride) (PVDF) that is also employed as a common polymer electrolyte material can exhibit a wide electrochemical window enabling constant high voltage due to the existence of strongly electron withdrawing groups (−C−F), 31 while its interface to lithium metal anodes always appears unstable, resulting in poor cycling performance. 32,33 The promising efforts to overcome such incompatibility between a wide electrochemical window and good interface stability focuses on constructing multilayer SCEs with Janus characteristics. 21,23,28,30,33 Herein, novel double-layer SCEs consisting of an antioxidative PVDF-based layer facing the cathode and a lithium metal-friendly (PEO+PVDF)-based layer against the anode, are proposed for room-temperature high-voltage LMBs.…”

Designing Polymer‐in‐Salt Electrolyte and Fully Infiltrated 3D Electrode for Integrated Solid‐State Lithium Batteries

“…This multicomponent interface layer delivered promising ionic conductivity, excellent electronic insulation, and good mechanical property, which should be responsible for the suppressed side reactions and sustainable lithium plating/stripping. [44,54] The PVHLi-1.1 PISSE also enabled the high-voltage operation (ca. 4.3 V) of commercial NCM523 cathode.…”

“…Characteristic peaks around 188, 208, and 408 are detected, which indicates that the PVDF-HFP matrix includes a-phase PVDF-HFP. [44] The position of each diffraction peak does not change but its intensity decreases, which demonstrates the increase of amorphous region after mixing with the bis(trifluoromethane)sulfonimide lithium (LiTFSI). These confirm the role of LiTFSI in reducing the crystallinity of PVDF-HFP, thereby improving the ionic conductivity.…”

Solid‐State Lithium Metal Batteries with Extended Cycling Enabled by Dynamic Adaptive Solid‐State Interfaces

“…[15,16] Efforts to enhance the solid contact interface have been focused on adding a trace of liquid electrolytes at the interface, constructing a thin artificial alloy interface with high wettability, or designing ceramic-polymer composite electrolytes that could possess both the advantages of ceramic and polymer electrolytes. [17][18][19][20][21][22][23][24][25][26][27][28] For instance, adding extra Li-Al, Li-Si, Li-Au, Li-ZnO, and Li-C/Ag alloy interface layers could improve the wettability of the SSE surface and facilitated rapid Li +transportation at the interface. [17][18][19][20][21][22] These delicate interfaces were more compatible with Li-metal to boost Li-nucleation.…”