Hierarchical Interconnected Hybrid Solid Electrolyte Membrane for All-Solid-State Lithium-Metal Batteries Based on High-Voltage NCM811 Cathodes

Abstract

Although hybrid solid electrolyte (HSE) membranes containing a small amount of ceramic filler are promising electrolytes for all-solid-state Li-metal batteries (ASSLMBs), they face various challenges while charging at high cut-off voltages. In this study, we prepared a high voltage-friendly flexible hierarchical interconnected hybrid solid electrolyte (HIHSE) membrane through polymer-based solution injection into a threedimensional (3D) interconnected c-LALZO framework (Li 6.25 Al 0.25 La 3 Zr 2 O 12 , fabricated using a template method). The HIHSE membrane possessed bulk (σ b ), grain boundary (σ gb ), and total ionic conductivities of 4.54, 0.30, and 0.28 mS cm −1 , respectively, with a Li + ion transference number of 0.66 and an electrochemical stability window of up to 4.90 V (vs Li/Li + ). The HIHSE membrane also displayed desirable Li plating/stripping performance, with very stable voltage hysteresis at a current density of 0.2 mA cm −2 over 800 h. A Li 2 MoO 4 @LiN 0.8 C 0.1 M 0.1 O 2 (LMO@NCM811)/HIHSE/Li full cell exhibited an excellent capacity retention of 86.14% after 400 cycles, with an average Coulombic efficiency of 99.27%, when operated at a rate of 0.5C in the voltage range of 2.6−4.2 V at room temperature (RT). Moreover, a cell with similar formulation delivered an excellent capacity output of 197.55 mAh g −1 , with an excellent capacity retention of 89.22% after 100 cycles and an average Coulombic efficiency of 99.11% at a rate of 0.1C in the potential range of 2.6−4.5 V at RT. Surprisingly, the performance of an ASSLMB incorporating our HIHSE membrane maximized at the upper limit potential of 4.5 V. Hence, ASSLMBs featuring such HIHSE membranes have great potential for use in high-voltage cathode materials while also increasing the energy density of Li-metal batteries.

Improved electrochemical performance of solid-state lithium metal batteries with stable SEI and CEI layers via in situ formation technique

“…Here, the Li-ion chemical environment in the LiTFSI salt and LALZO is located in the upeld and downeld directions (about each other), respectively, which is consistent with the previously reported results. 13,40 We further studied the possible Li-ion migration pathways aer cycling by assembling a symmetric cell of mLi/SHSE0/mLi and mLi/SHSE1/mLi, followed by galvanostatic testing at 0.2 mA cm −2 for 100 h. Subsequently, the cells were disassembled in a glove box lled with Ar gas for a 6 Li NMR spectroscopic analysis. Fig.…”

“…Such a shi in the 6 Li NMR peak suggests a change in the local environment of Li + in the composite membrane system. 40,46 The probable reason for this may be due to the synergistic effect of the well-dispersed PDA-modied LALZO llers in all layers of the composite membrane-facilitating the Lewis acid-base complexation reaction. Furthermore, in addition to the units of the PVDF-HFP polymer, the presence of highly electron-withdrawing catechol and secondary amine functional units on PDA resulted in a strong interaction with Li + in the middle or across the interface of the corresponding membrane.…”

“…However, the coin-type cell with the same constituent but using the SHSE0 membrane (i.e., Li-Nf@NCM811/SHSE0/ mLi) suffered from overcharging starting from 162 cycles, which might be due to the uneven current distribution and growth of lithium dendrites at the electrode/electrolyte interface during long cycling and fast charging-discharging at a rate of 1C. 40,63,64 The superior electrochemical performance of the SHSE1-based composite solid electrolyte membrane is plausibly due to its wider electrochemical stability window, unique design, and improved interfacial stability with LMA. 6 This promotes effective lithium nucleation and uniform deposition at the electrode/electrolyte interface.…”

State-of-the-Art of Solid-State Electrolytes on the Road Map of Solid-State Lithium Metal Batteries for E-Mobility

“…One wt % LiNf@f-MWCNT polymer matrix when coated to the side of the electrolyte facing the Li anode is expected to suppress Li dendrite formation, providing a higher Coulombic efficiency of 99.6%. 129 In another study, three-dimensional (3D) interconnected c-LALZO framework not only enabled one to suppress dendrite but also improved the upper limit voltage up to 4.5 V. 130 In another research study, efforts were put into fabricating a composite electrolyte with Li 6.28 La 3 Zr 2 Al 0.24 O 12 (Al-LLZO, as the filler), poly(vinylidene fluoride)/poly(ethylene carbonate) (PVDF/ PEC, as the blended polymer), and lithium bis-(trifluoromethanesulfonyl)imide (LiTFSI, as the salt) wherein the mechanical strength was improved up to 11.36 MPa while maintaining higher ambient conductivity and Li transference number. 131 There are several efforts to improve conductivity while balancing the mechanical strength of the electrolyte membranes; however the choice of selecting the inorganic ceramic electrolytes and the matching polymers along with lithium salt mainly relies on the experimental trials and an estimated hypothesis.…”

Pyrene-Based Cationic Fluorophores with High Affinity for BF4–, PF6–, and ClO4– Anions: Detection and Removal

“…Anions illustrating a 3D spatial structure, such as BF 4 – and PF 6 – , have been widely used as ionic liquids in catalysis and in the lithium-ion battery industry. , However, their extensive application has also caused a series of environmental issues. For example, as lithium-ion technology has developed, new energy vehicles have entered our everyday life, but this has also led to new challenges such as how to recycle the lithium-ion batteries as well as electrolytes .…”