Improving Lithium Battery Performance Over 2000 Hours with Metal Compounds... About 4 Times Better Than Existing Ones

Published 25 Apr.2023 16:10(KST)

Updated 07 Aug.2025 14:09(KST)

Recently, a technology has been developed to improve the quality of lithium metal electrode surfaces using alloy phase diagrams.

An alloy phase diagram is an indicator that allows the prediction of whether and how heterogeneous elements will alloy with lithium. Based on this, attention is being drawn to the successful development of lithium metal alloys with controllable side reactions formed on the electrolyte surface without the aid of electrolyte additives.

The research team led by Professor Hyunwook Lee from the Department of Energy Chemical Engineering at UNIST conducted a study using metal fluoride (MxFy) compounds.

By using these compounds, the team developed an electrode processing technology consisting of a lithium fluoride protective layer with excellent chemical resistance on the metal surface and a lithium alloy with enhanced lithium atom mobility inside, significantly improving the performance of lithium batteries.

Lithium metal, known as an ideal next-generation anode material due to its high capacity and low operating voltage, suffers from short lifespan and potential fire hazards caused by uneven dendritic formation of electrochemically deposited lithium and side reactions with the electrolyte during battery operation.

Mechanism of lithium fluoride film formation and internal lithium alloying using metal fluoride compounds (MxFy).

In particular, the newly formed lithium surface during lithium plating continuously reacts with the organic electrolyte. This causes loss of lithium electrolyte and the formation of a thick film layer that greatly degrades performance.

The research team embarked on a study to enhance the performance of lithium batteries.

First, they utilized the properties of metal fluorides, which actively react with lithium even under low heat treatment conditions. In this process, lithium fluoride forms a surface protective layer that can shield the internal lithium alloy from the electrolyte.

This lithium alloy electrode demonstrated a battery lifespan improved by about four times, exceeding approximately 2000 hours, compared to conventional lithium electrodes when operated in an electrolyte system containing electrolyte additives.

Moreover, the surface processing technology proved its excellence by maintaining stable operation for over 700 hours even in an electrolyte system without electrolyte additives.

The research team also elucidated the mechanism by which metal fluoride compounds react with lithium using real-time transmission electron microscopy analysis.

Minho Kim, a postdoctoral researcher in the Department of Energy Engineering at UNIST and the first author, stated, “This study presented a benchmark for creating lithium alloys with improved interfacial properties compared to conventional lithium metal by using alloy phase diagrams.”

He added, “This surface modification technology perfectly complements the incomplete formation of lithium surface protective layers caused by electrolyte additives, which had been largely overlooked, and will serve as a guideline for the commercialization of lithium metal batteries.”

Professor Hyunwook Lee of the Department of Energy Chemical Engineering said, “Due to global issues surrounding secondary batteries, developing high-performance and novel materials has become crucial enough to determine technological leadership. Especially when discovering new materials, understanding their mechanisms has become more important than ever.”

He continued, “UNIST has established an all-in-one analysis center capable of advanced analysis of secondary and next-generation batteries. With this infrastructure, we aim to serve as a headquarters that identifies many materials developed by Korean researchers and diagnoses how to improve secondary battery performance.”

The research was supported by the Ulsan National Institute of Science and Technology’s Future Leading Specialized Project, the Ministry of Science and ICT and Korea Research Foundation’s Mid-career Linked New Follow-up Project, and the Climate Change Response Technology Development Project. It was published online on April 7 in the internationally renowned nanomaterials journal Nano Letters.