Negative electrode layer for all-solid secondary battery, all-solid secondary battery including the same, and preparation method thereof

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Solution Overview

Problem

Existing all-solid secondary batteries face challenges with lithium metal as a negative active material due to its softness under high-temperature and high-pressure conditions, leading to deformation and short-circuits, and limited lithium content results in reduced battery lifespan.

Innovation Solution

A novel negative electrode layer is introduced, comprising a lithium metal composite (LMC) with lithium metal and an inorganic negative active material, which is more elastic and harder than pure lithium, preventing liquefaction and short-circuits during pressing, and serving as an additional lithium reservoir to enhance battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal is used as a negative active material under high-temperature and high-pressure conditions, then the battery achieves high energy density, but the lithium metal deforms and causes short-circuits

Engineering Contradiction:

Improveenergy densityVSAvoidshort-circuit prevention

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses a composite negative active material layer comprising lithium metal particles dispersed in a carbon matrix. The carbon matrix provides mechanical support and structural stability to prevent lithium deformation under high-temperature and high-pressure conditions, while the lithium metal particles maintain high energy density. This composite structure resolves the contradiction by combining the high energy density of lithium metal with the structural stability of carbon.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If lithium metal is used as a negative active material, then the battery achieves high energy density, but the lithium metal behaves like a gel and causes electrode plate deformation

Engineering Contradiction:

Improveenergy densityVSAvoidelectrode plate deformation

Core Design Contradiction:

Use of energy by moving objectVSShape

Solution Approach 1:

The patent employs a composite structure where lithium metal particles are embedded in a carbon matrix. The carbon component provides rigid structural support that prevents the lithium metal from deforming into a gel-like state, maintaining electrode plate shape stability while preserving the high energy density benefits of lithium metal.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different parts of the negative active material layer. The carbon matrix provides structural stability and shape maintenance, while the lithium metal particles localized within the matrix provide high energy density. This local differentiation of material functions resolves the contradiction between energy density and shape stability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250079470A1Negative electrode layer for all-solid secondary battery, all-solid secondary battery including the same, and preparation method thereof

Publication Date: 2025.03.06 SAMSUNG SDI CO LTD

AI summary

Provided are a negative electrode layer for sulfide-based solid electrolyte-containing all-solid secondary batteries, an all-solid secondary battery including the same, and a preparation method thereof, wherein the negative electrode layer includes a negative current collector and a first negative active material layer, and the first negative active material layer includes a lithium metal composite including lithium metal and an inorganic negative active material.