Tailoring of Li/LATP-PEO Interface via a Functional Organic Layer for High-Performance Solid Lithium Metal Batteries

Abstract

Surface functionalization is an effective strategy to reduce the chemical reactivity between a Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) electrolyte and Li metal anode and optimize the interfacial contact of different components. Herein, sodium itaconate (SI) is introduced to modify the surfaces of LATP particles (LATP@SI) via a self-polymerizing process, and a composite solid electrolyte (CSE) composed of poly(ethylene oxide) (PEO) and LATP@SI is fabricated. Benefiting from the protection of the SI nanolayer, LATP demonstrates chemical compatibility with the Li metal anode, while the reduced surface energy renders a good dispersion of LATP in PEO. Furthermore, abundant carboxyl groups in SI can offer a bridge between LATP and PEO to accelerate Li + transmission. As a result, the as-prepared PEO-LATP@SI-6 CSE exhibits a high ionic conductivity of 1.15 × 10 −4 S cm −1 at 30 °C and 1.20 × 10 −3 S cm −1 at 60 °C, a wide electrochemical stable window beyond 5.0 V, an improved Li + transference number of 0.41, and an optimized lithium compatibility over 1200 h with Li dendrite free. The as-assembled Li||PEO-LATP@SI-6 CSE||LiFePO 4 full battery delivers a high reversible capacity of 155 mAh g −1 and an outstanding capacity retention of 89% after 200 cycles. The Li|| LiFePO 4 pouch cell also successfully runs 50 cycles with a terminal discharge capacity of 116.6 mA h g −1 . This study opens a new avenue to protect LATP. The developed surface functionalization technique promises a facile and efficient method for interfacial engineering to accelerate the practical application of LATP in solid-state lithium batteries.

Double-Layer Electrolyte Boosts Cycling Stability of All-Solid-State Li Metal Batteries

“…The electrochemical compatibility of LATP against Li metal can be enhanced by sodium itaconate (SI) as a protective layer . Similarly, Qian et al used a boron nitride (BN) nanofilm to separate the physical connection of the active anode and the LATP achieved by the chemical vapor deposition (CVD) method . The above works demonstrate that introducing an isolation layer between LATP and reducing materials is a feasible strategy to resolve the as-mentioned problem, though challenges of the complicated preparation process, high fabrication costs, and disconnection of the modification layer during cycling still restrict their practical application.…”

“…On the one hand, the interface impedance between electrode/electrolyte (especially cathode/electrolyte) significantly increases resulting from the rigid feature of LATP, leading to the deteriorative cycling performance of batteries. On the other hand, severe irreversible reductions corresponding to the Ti 4+ /Ti 3+ redox couple will occur when the LATP and the Li metal anode are directly contacting. − These side reactions will consume the LATP and the active material, causing the amplified interface impedance and the failure of batteries. In terms of the electrode/electrolyte interface, preparing a composite solid-state electrolyte (CSE) containing LATP is considered an effective strategy. − Specifically, the CSE is fabricated by introducing LATP into a polymer matrix (e.g., PEO and PVDF).…”

“…Despite room-temperature ion conductivity and the interfacial contact properties having already been greatly improved in CSEs, the issue of irreversible reductions of LATP still exists in CSEs (Figure S1). To fill the gap hampering the successful utilization of LATP in AASLMBs, surface modification of LATP is proposed as a feasible way to enhance chemical compatibility with Li metal. ,,− For instance, a PEO-based CSE with core–shell-structured LATP@SI was fabricated by Yang et al via a self-polymerizing process . The electrochemical compatibility of LATP against Li metal can be enhanced by sodium itaconate (SI) as a protective layer .…”

“…26 Similarly, Qian et al used a boron nitride (BN) nanofilm to separate the physical connection of the active anode and the LATP achieved by the chemical vapor deposition (CVD) method. 34 The above works demonstrate that introducing an isolation layer between LATP and reducing materials is a feasible strategy to resolve the as-mentioned problem, though challenges of the complicated preparation process, high fabrication costs, and disconnection of the modification layer during cycling still restrict their practical application. Obviously, discovering a non-complicated and long-term effective method for strengthening the chemical compatibility of LATP with Li metal in AASLMBs is still an enduring inspiration for researchers.…”

LLZTO Nanoparticle- and Cellulose Mesh-Coreinforced Flexible Composite Electrolyte for Stable Li Metal Batteries

“…Driven by the urgent need for higher energy density, better safety, and longer cyclic life for both mobile and stationary applications, growing attention has been paid to solid-state batteries. − One of the major factors in developing solid-state batteries is the possibility of utilizing the Li metal with high specific capacity and low redox potential as the anode active material. , Despite its promising properties and progress made, there are still numerous challenges before the commercial use of the Li metal anode. Typically, in conventional batteries with organic liquid electrolytes, the unstable Li/electrolyte interface caused by severe interfacial side reactions and uncontrolled Li dendrite propagation is the most prominent issue. , Furthermore, organic liquid electrolytes are highly flammable and can cause hazardous accidents as a result of short circuits and thermal runaway in the battery system .…”