Secondary Battery Positive Electrode Double Coating

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for covering positive electrodes in secondary batteries, such as those using lithium-ion conductive glass, lead to a decrease in crystallinity and increased internal resistance due to the prevention of lithium ion transfer.

Innovation Solution

A double-coating method is employed, where a first coating of oxide X, containing a metal element M1, is applied to the positive electrode active material particles, followed by a second coating with lithium-ion permeability, represented by LixM2Oy, to maintain crystallinity and suppress side reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a low-crystalline glass material is used to cover the positive electrode active material, then side reactions are suppressed, but the crystallinity of the surface decreases and lithium ion transfer is prevented, increasing internal resistance

Engineering Contradiction:

Improvesuppression of side reactionsVSAvoidcrystallinity of surface

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The protective coating is divided into two distinct layers: a first coating layer that maintains crystallinity and enables lithium ion transfer, and a second coating layer that suppresses side reactions. This segmentation allows each layer to perform its specific function without compromising the other, resolving the contradiction between suppressing side reactions and maintaining lithium ion conductivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite coating structure combining two different materials with complementary properties. The first coating material preserves the crystalline structure for ion transport, while the second coating material provides chemical stability to prevent side reactions. This composite approach allows the system to achieve both goals simultaneously.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a protective layer is applied to cover the positive electrode, then side reactions are suppressed, but the transfer of lithium ions is prevented, increasing internal resistance

Engineering Contradiction:

Improvesuppression of side reactionsVSAvoidinternal resistance

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the coating have different properties optimized for their specific functions. The first coating layer has properties optimized for maintaining crystallinity and lithium ion conductivity, while the second coating layer has properties optimized for suppressing side reactions. This local differentiation allows the system to achieve both protection and conductivity.

Inventive Principle:

Principle #3Local quality

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

This approach effectively reduces internal resistance and enhances the performance of secondary batteries by stabilizing the crystallinity of the positive electrode active material surface while preventing side reactions.

Implementation Method 1

a second coating having lithium-ion permeability that is attached to the surface of the first coating

Methodology Applied

Scientific EffectLithium-ion conductivity: Conduction (electrical)

Data Source

PatentUS11594720B2Positive electrode for secondary battery, secondary battery, and method for producing positive electrode for secondary battery

Publication Date: 2023.02.28 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A positive electrode for a secondary battery includes a positive electrode current collector and a positive electrode active material layer that contains a positive electrode active material particle and that is disposed on the surface of the positive electrode current collector. The positive electrode active material particle includes a positive electrode active material particle, a first coating that contains oxide X of metal element M1 and that is attached to the surface of the positive electrode active material particle, and a second coating having lithium-ion permeability that is attached to the surface of the first coating. The second coating contains oxide Y represented by LixM2Oy (0.5≤x<4, 1≤y<6), M2 being at least one selected from a group consisting of B, Al, Si, P, S, Ti, V, Zr, Nb, Ta, and La.