Coated Positive Electrode Structure for Low-Resistance Li-Ion Batteries

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Solution Overview

Problem

Conventional positive electrodes for non-aqueous electrolyte secondary batteries exhibit high resistance, leading to poor post-storage low-temperature output and low energy density.

Innovation Solution

A positive electrode design featuring a positive electrode current collector with a current collector coating layer and a positive electrode active material layer containing coated positive electrode active material particles, a particulate binder, and a conducting agent, with specific mass and particle diameter ratios, enhances conductivity and reduces binder and conducting agent content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a conventional positive electrode composition containing anionic dispersant and water is used to improve dispersibility of positive electrode active material particles, then dispersibility is improved, but the battery exhibits high resistance and poor post-storage low-temperature output

Engineering Contradiction:

Improvedispersibility of positive electrode active material particlesVSAvoidpost-storage low-temperature output

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The invention changes the chemical composition parameters of the positive electrode composition by replacing conventional anionic dispersants with specific polymers having carboxyl groups and hydroxyl groups in specific ratios. The polymer structure parameters (molar ratio of carboxyl to hydroxyl groups between 0.1-10, average degree of polymerization 500-5000) are optimized to achieve both excellent dispersibility and maintained battery performance after storage, resolving the contradiction between dispersibility improvement and performance degradation.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional positive electrode composition is used to simplify manufacturing, then ease of manufacture is improved, but energy density and conductivity are reduced

Engineering Contradiction:

Improvesimplicity of positive electrode productionVSAvoidenergy density

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The invention employs a composite polymer material combining carboxyl groups and hydroxyl groups in specific ratios, along with specific conductive materials and positive electrode active materials. This composite approach maintains manufacturing simplicity while achieving high energy density through optimized material interactions and reduced binder content, overcoming the limitation of conventional single-component dispersants.

Inventive Principle:

Principle #40Composite materials

3Strength

If binder content is increased to improve electrode structure stability, then structural integrity is improved, but conductivity and energy density decrease

Engineering Contradiction:

Improvestructural integrity of positive electrodeVSAvoidconductivity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention optimizes the chemical structure parameters of the binder polymer, specifically the molar ratio of carboxyl groups to hydroxyl groups (0.1-10) and average degree of polymerization (500-5000), to achieve maximum binding efficiency at lower concentrations. This parameter optimization maintains structural integrity while minimizing the volume occupied by binder, thereby preserving conductivity and energy density.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention extracts and removes excess binder material from the positive electrode composition, relying on the high-efficiency binding mechanism of the specially designed polymer to maintain structural integrity with minimal binder content (1-10 parts by mass per 100 parts of positive electrode active material). This extraction of unnecessary binder reduces resistance and improves energy density while maintaining structural strength.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20260005249A1Non-aqueous electrolyte secondary-battery positive electrode, non-aqueous electrolyte secondary battery using the same, battery module, and battery system

Publication Date: 2026.01.01 SEKISUI CHEMICAL CO LTD

AI summary

A positive electrode for a non-aqueous electrolyte secondary battery, including a positive electrode current collector and a positive electrode active material layer provided on the positive electrode current collector, wherein: the positive electrode active material layer includes positive electrode active material particles with at least part of their surfaces being coated with a conductive material; the positive electrode current collector includes a positive electrode current collector main body and a current collector coating layer present on a surface of the positive electrode current collector main body on a side of the positive electrode active material layer; and the positive electrode active material layer includes a particulate binder.