Conductive and Stable CPE Interlayer Solves NASICON Solid-State Battery Challenges, Enabling Over 300 Hours Stable Cycling and 90% Capacity Retention

July 19, 2026

ACS Publications International

Overview

NASICON-based solid electrolytes are promising candidates for all-solid-state lithium batteries due to high ionic conductivity and wide electrochemical stability, but interfacial side reactions with lithium metal anodes hindered their practical use. This study proposes a mechanism-guided design incorporating a conductive and stable composite polymer electrolyte (CPE) interlayer between the LAGP solid electrolyte and lithium metal anode. This interlayer enabled Li|CPE|LAGP|CPE|Li symmetric cells to cycle stably for over 300 hours, and all-solid-state full cells retained 90% capacity after cycling, marking a significant step towards NASICON-based solid-state battery commercialization.

In Depth

Key Findings

NASICON-based solid electrolytes, possessing excellent properties such as high lithium-ion conductivity and a wide electrochemical stability window, have been considered highly promising candidates for all-solid-state lithium batteries. However, interfacial side reactions with lithium metal anodes posed a significant challenge, hindering their practical application. To address this fundamental problem, this study proposes a ‘mechanism-guided design’ that introduces a composite polymer electrolyte (CPE) interlayer, balancing both conductivity and stability, between the LAGP (lithium aluminum germanium phosphate) solid electrolyte and the lithium metal anode. This innovative interlayer enabled Li|CPE|LAGP|CPE|Li symmetric cells to exhibit stable cycling performance for over 300 hours, and constructed all-solid-state full cells retained an excellent 90% of their initial capacity even after numerous cycles.

Technical / Clinical Details

While NASICON-based solid electrolytes are attractive for their high ionic conductivity, they tend to destabilize upon contact with lithium metal, forming high-resistance interfacial layers or inducing dendrite growth. The proposed CPE interlayer is designed to suppress reactivity with lithium on the anode side while maintaining good contact with the LAGP solid electrolyte. This interlayer also possesses ionic conductivity, ensuring smooth lithium-ion transport. The stable cycling for over 300 hours in symmetric cells demonstrates that the interlayer effectively suppresses dendrite formation and provides long-term interfacial stability. Furthermore, the 90% capacity retention in full cells implies that this design can achieve a balance between practical energy density and lifespan, making it highly promising for applications such in electric vehicles and large-scale energy storage systems.

Background & Context

All-solid-state batteries are being extensively researched and developed worldwide as a next-generation technology to overcome the limitations of conventional liquid-electrolyte lithium-ion batteries in terms of safety (thermal runaway, fire risk) and performance (energy density, cycle life). NASICON-based solid electrolytes have attracted attention for their excellent bulk conductivity for many years, but the interfacial problems with lithium metal anodes have consistently been a bottleneck for commercialization. This research is critically important for addressing this fundamental challenge from an interfacial engineering perspective and providing a practical solution. The design of an interlayer that combines both conductivity and stability offers crucial insights into a common challenge in solid-state battery development aiming for high energy density and long lifespan.

Strategic Significance & Outlook

The introduction of a CPE interlayer that balances both conductivity and stability is a groundbreaking step that will accelerate the commercialization of NASICON-based all-solid-state batteries. Further development of this technology will enable the creation of safer, higher-performing, and longer-lasting solid-state batteries, significantly contributing to improvements in electric vehicle range and charging times. Applications are also expected in other high-reliability and high-durability demanding fields, such as grid storage for renewable energy, aerospace, defense, and portable electronic devices. Future research will focus on improving the scalability and cost-efficiency of the interlayer manufacturing process, as well as verifying compatibility with higher-voltage cathode materials. This design approach also holds potential for application to various solid electrolyte systems.

Source: https://pubs.acs.org/doi/10.1021/acs.acsaem.6c01337

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