Negative electrode and solid-state secondary battery including the same

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Solution Overview

Problem

Current lithium-ion batteries using liquid electrolytes pose safety risks due to the presence of combustible organic solvents, which can lead to overheating and fires upon short circuit. There is a need for solid-state batteries with solid electrolytes to enhance safety.

Innovation Solution

A negative electrode with a new structure is developed, comprising a negative electrode current collector with a first metal substrate and a coating layer containing a second metal with higher Mohs hardness. This structure prevents deterioration of the current collector and reduces the risk of short circuits in solid-state secondary batteries.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a soft metal substrate (e.g., copper) is used for the negative electrode current collector, then electrical conductivity and electrochemical stability are improved, but the current collector deteriorates during battery operation, leading to micro-cracks and short circuits

Engineering Contradiction:

Improvecurrent collector stabilityVSAvoidcurrent collector hardness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies composite materials by combining a soft metal substrate (copper or aluminum) with a hard metal coating layer (chrome, nickel, or titanium). This composite structure allows the soft substrate to maintain electrical conductivity and electrochemical stability while the hard coating layer prevents deterioration and micro-crack formation during battery operation.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the negative electrode current collector is made harder to prevent deterioration, then reliability is improved, but the uniformity of the lithium-containing metal layer deteriorates

Engineering Contradiction:

Improvecurrent collector durabilityVSAvoidlithium layer uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating a layered structure where different regions of the current collector have different properties. The substrate provides softness for uniform lithium deposition, while the surface coating layer provides hardness for durability. This local differentiation of material properties resolves the contradiction between hardness and lithium layer uniformity.

Inventive Principle:

Principle #3Local quality

3Use of energy by moving object

If liquid electrolytes are used in lithium-ion batteries, then electrochemical performance is improved, but safety risks increase due to combustible organic solvents

Engineering Contradiction:

Improvebattery performanceVSAvoidfire risk

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by transitioning from liquid electrolytes to solid electrolytes, fundamentally changing the physical state parameter of the electrolyte. This change eliminates the combustibility issue while maintaining ionic conductivity, thereby improving safety without sacrificing electrochemical performance.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250140869A1Negative electrode and solid-state secondary battery including the same

Publication Date: 2025.05.01 SAMSUNG SDI CO LTD

AI summary

A negative electrode includes a negative electrode current collector and a first negative electrode active material layer on the negative electrode current collector, wherein the negative electrode current collector includes a first metal substrate including a first metal, and a coating layer positioned on the first metal substrate and containing a second metal, the second metal having a greater Mohs hardness than the first metal.