Modified Lithium Metal Anode for Low-Impedance Solid-State Interfaces

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Solution Overview

Problem

Lithium metal negative electrodes in lithium batteries are prone to react with other substances, forming dendrites that can pierce the electrolyte and cause short circuits due to poor interfacial chemical stability and high impedance with solid-state electrolytes.

Innovation Solution

A negative electrode with a metallic lithium layer modified by organic substances and non-metallic lithium compounds, including halogens and ether groups, reduces direct contact with the solid-state electrolyte, improving interfacial impedance and lithium ion deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high-strength solid-state electrolytes are used to prepare all-solid-state batteries, then energy density is enhanced, but interfacial chemical stability deteriorates and interfacial impedance increases

Engineering Contradiction:

Improveenergy densityVSAvoidinterfacial chemical stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An artificial solid electrolyte interphase (SEI) layer is introduced as an intermediary between the lithium metal anode and the solid-state electrolyte. This SEI layer comprises a lower layer containing lithium fluoride (LiF) and an upper layer containing lithium oxide (Li2O) and lithium hydroxide (LiOH), which mediates the interface to improve chemical stability while maintaining low impedance for lithium ion transport.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The artificial SEI layer is constructed as a composite material system with distinct functional layers. The lower layer uses LiF for chemical stability and the upper layer uses Li2O and LiOH for lithium ion conductivity, creating a composite structure that simultaneously addresses both chemical stability and impedance issues at the interface.

Inventive Principle:

Principle #40Composite materials

2Speed

If solid-state electrolyte contacts metallic lithium directly, then lithium ion transport is achieved, but contact uniformity deteriorates and dendrite growth is promoted

Engineering Contradiction:

Improvelithium ion transportVSAvoidcontact uniformity

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The artificial SEI layer serves as a mediator that ensures uniform contact between the lithium metal anode and the solid-state electrolyte. The layered structure with different compositions (LiF in lower layer, Li2O and LiOH in upper layer) provides both mechanical compliance and chemical stability, promoting uniform lithium ion flux distribution and preventing localized dendrite formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If modification layer with organic substances and non-metallic lithium compounds is applied, then interfacial impedance is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improveinterfacial impedanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The artificial SEI layer is formed preliminarily before the battery is assembled and put into operation. By pre-forming the protective interface layer with the desired composition and structure, the system avoids the need for complex in-situ formation processes during battery operation, thereby reducing manufacturing complexity while achieving low interfacial impedance.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances battery safety and cycle performance by inhibiting dendrite growth and reducing interfacial impedance, facilitating uniform lithium ion transport and increasing energy density.

Implementation Method 1

contacting a metallic lithium sheet with a gaseous halogen-containing ether compound to obtain the negative electrode

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

the modification layer can include organic substances and non-metallic lithium compounds... reducing direct contact with the solid-state electrolyte, improving interfacial impedance

Methodology Applied

Scientific EffectInterfacial impedance reduction:

Implementation Method 3

facilitating uniform lithium ion transport and increasing energy density

Methodology Applied

Scientific EffectIon transport: Ion Exchange

Data Source

PatentEP4675698A1Negative electrode and preparation method therefor, solid-state battery and electric device

Publication Date: 2026.01.07 SUNWODA MOBILITY ENERGY TECHNOLOGY CO LTD

Figure 1~3

AI summary

The present invention relates to the technical field of lithium battery materials, and in particular relates to a negative electrode and a preparation method therefore, a solid-state battery and an electric device. The negative electrode comprises a metal lithium layer and a modification layer positioned on at least one surface of the metal lithium layer, wherein the modification layer comprises organic matter and a non-metal lithium compound, the organic matter comprises halogen and an ether group, and the arithmetic average roughness of the modification layer is 0.05 - 1.6 nm. In the negative electrode, the metal lithium layer is modified with the specific organic matter and the non-metal lithium compound, such that direct contact between a solid electrolyte and metal lithium can be reduced, the interface impedance is reduced, and the deposition of lithium ions is facilitated; therefore, the utilization rate of the battery is increased, and the cycle life of the battery is prolonged.