Lithium Metal Anode Protective Layer Against Dendrite Penetration

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Solution Overview

Problem

Lithium secondary batteries face challenges in controlling lithium metal deposition and suppressing the growth of dendrites, leading to degraded cycle characteristics due to the penetration of dendrites through the surface film and subsequent side reactions with the non-aqueous electrolyte.

Innovation Solution

A lithium secondary battery design featuring a negative electrode with a protective layer composed of a resin material and inorganic particles with a density of 6 g/cm3 or more, which enhances the strength and lithium ion conductivity of the layer, preventing dendrite penetration and maintaining cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a surface film is formed on the negative electrode to suppress lithium metal deposition, then local deposition and dendrite growth are suppressed, but the surface film strength is low and dendrites penetrate through it

Engineering Contradiction:

Improvecycle characteristicsVSAvoidsurface film strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies composite materials by combining resin material with inorganic particles (having a density of 6 g/cm3 or more) to form a protective layer. This composite structure provides both the film-forming capability to suppress lithium deposition and the mechanical strength to prevent dendrite penetration, resolving the contradiction between surface film strength and cycle characteristics.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If the negative electrode surface is made smooth (Rz ≤ 10 μm) to suppress dendrite formation, then local lithium deposition is reduced, but dendrites still penetrate through the weak surface film

Engineering Contradiction:

Improvesurface roughness controlVSAvoidcycle characteristics

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent combines smooth surface control (Rz ≤ 10 μm) with composite protective layer formation using resin material and high-density inorganic particles. This dual approach maintains manufacturing precision for surface smoothness while adding the strength component needed to prevent dendrite penetration and maintain cycle characteristics.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The protective layer with inorganic particles provides localized reinforcement at the negative electrode surface where dendrite penetration occurs, while maintaining the overall smooth surface morphology. This local quality enhancement addresses the weakness of the surface film without compromising the global surface smoothness.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If inorganic particles with low density are used in the protective layer, then the layer is easier to form, but the layer strength is insufficient to prevent dendrite penetration

Engineering Contradiction:

Improveprotective layer formationVSAvoidprotective layer strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent specifies using inorganic particles with a density of 6 g/cm3 or more, which is a significant parameter change from conventional low-density particles. This parameter change provides sufficient mechanical strength to prevent dendrite penetration while maintaining manufacturability through standard coating processes.

Inventive Principle:

Principle #35Parameter changes

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

The protective layer effectively suppresses dendrite penetration and side reactions, thereby improving the cycle characteristics and reliability of the lithium secondary battery.

Implementation Method 1

the inorganic particles have a density of 6 g/cm3 or more

Methodology Applied

Scientific EffectDensity:

Implementation Method 2

a non-aqueous electrolyte that has lithium ion conductivity

Methodology Applied

Scientific EffectIon conductivity: Conduction (electrical)

Implementation Method 3

lithium metal is deposited on the negative electrode during charging, and the lithium metal dissolves and is released as lithium ions into the non-aqueous electrolyte during discharging

Methodology Applied

Scientific EffectDeposition: Deposition (physical)

Data Source

PatentUS20230369639A1Lithium secondary battery

Publication Date: 2023.11.16 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A lithium secondary battery includes: a positive electrode that absorbs lithium ions during discharging and releases the lithium ions during charging; a negative electrode on which lithium metal is deposited during charging and from which the lithium metal dissolves during discharging; and a non-aqueous electrolyte that has lithium ion conductivity. A surface of the negative electrode is covered with a protective layer that contains a resin material and inorganic particles having a density of 6 g/cm3 or more.