Lithium Battery Negative Electrode Protrusions for Dendrite Accommodation

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Solution Overview

Problem

Lithium secondary batteries face challenges in maintaining charge/discharge efficiency and preventing negative electrode expansion due to dendritic lithium metal deposition, which limits their capacity and safety.

Innovation Solution

A lithium secondary battery design featuring a negative electrode current collector with protrusions on its surface, allowing for controlled lithium metal deposition and accommodation, reducing electrode expansion and enhancing electrolyte distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium metal is deposited on the negative electrode during charge, then the capacity of the battery is increased, but the negative electrode expands due to dendritic deposition

Engineering Contradiction:

Improvelithium metal depositionVSAvoidnegative electrode expansion

Core Design Contradiction:

Quantity of substanceVSVolume of moving object

Solution Approach 1:

The negative electrode current collector surface is segmented into multiple protrusions that are spatially separated and do not divide the first surface into parts. This segmentation allows lithium metal to be deposited in distributed locations rather than concentrating in single areas, thereby accommodating volume expansion while maintaining overall electrode integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from a flat two-dimensional current collector surface to a three-dimensional structure with protrusions having height, width, and spacing. This dimensional change creates vertical space for lithium metal deposition without increasing the horizontal footprint, effectively managing electrode expansion in the Z-direction while maintaining compact battery design

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If the surface of the negative electrode current collector is made rough to accommodate lithium metal, then the deposition is improved, but the electrolyte distribution becomes non-uniform

Engineering Contradiction:

Improvelithium metal depositionVSAvoidelectrolyte distribution uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The current collector surface exhibits local quality variations through protrusions with specific height ranges (10-500 μm) and area ratios (1-50%), creating localized deposition zones while maintaining overall surface uniformity. This allows controlled lithium metal deposition in specific regions without preventing electrolyte access to other areas, balancing deposition efficiency with electrolyte distribution

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention optimizes specific parameters of the protrusions including height (10-500 μm), area ratio (1-50%), and spacing to achieve desired performance. By carefully controlling these parameters, the surface provides sufficient roughness for lithium metal accommodation while maintaining electrolyte wettability and uniform distribution across the electrode surface

Inventive Principle:

Principle #35Parameter changes

3Reliability

If protrusions are added to the negative electrode current collector, then lithium metal deposition is controlled, but the device complexity increases

Engineering Contradiction:

Improvelithium metal deposition controlVSAvoidcurrent collector structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The current collector is designed with a porous-like structure featuring protrusions that create void spaces and surface area increases. This porous morphology provides numerous nucleation sites for lithium metal deposition, improving control over dendritic growth while maintaining a relatively simple fabrication process that can be achieved through conventional techniques like electrochemical etching or mechanical deformation

Inventive Principle:

Principle #31Porous materials

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 battery design reduces negative electrode expansion, improves discharge capacity, and enhances safety by accommodating lithium metal deposition and ensuring uniform electrolyte distribution, leading to improved charge/discharge efficiency and cycle characteristics.

Implementation Method 1

lithium metal is deposited on a negative electrode during charge

Methodology Applied

Scientific EffectElectrochemical reduction: Electrodeposition

Implementation Method 2

the lithium metal dissolves in a nonaqueous electrolyte during discharge

Methodology Applied

Scientific EffectElectrochemical oxidation: Electrodeposition

Implementation Method 3

nonaqueous electrolyte having lithium-ion conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS11177481B2Lithium secondary battery including nonaqueous electrolyte having lithium-ion conductivity

Publication Date: 2021.11.16 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A lithium secondary battery includes a positive electrode, negative electrode, a separator, and a nonaqueous electrolyte having lithium-ion conductivity. The positive electrode contains a positive electrode active material containing lithium. The negative electrode faces the positive electrode. The separator is disposed between the positive and negative electrodes. The negative electrode includes a negative electrode current collector. The negative electrode current collector includes a layer having a first surface, and protrusions protruding from the first surface. The first surface is a surface on which lithium metal is deposited during charge. The protrusions do not divide the first surface into parts.