Lithium Battery Cathode Structure for High-Pressure Rolling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium secondary batteries face challenges in achieving high compaction density and stability due to cracking of secondary macroparticles during electrode manufacturing, particularly with nickel-rich lithium transition metal oxides, leading to reduced life characteristics and thermal instability.

Innovation Solution

A positive electrode for lithium secondary batteries is designed with a multilayer structure comprising primary and secondary macroparticles and microparticles of varying sizes, allowing for high rolling pressure without cracking, using a current collector, a first positive electrode active material layer with primary macroparticles, and a second layer with secondary microparticles and macroparticles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If secondary macroparticles are used to increase compaction density, then compaction density is improved, but particle cracking occurs during rolling process

Engineering Contradiction:

Improvecompaction densityVSAvoidparticle strength

Core Design Contradiction:

Volume of stationary objectVSStrength

Solution Approach 1:

The positive electrode active material is divided into two distinct size fractions: secondary macroparticles (D50: 5-20 μm) and secondary microparticles (D50: 1-5 μm). This segmentation allows each particle size to fulfill different functions - macroparticles provide compaction density while microparticles fill voids and prevent cracking, resolving the contradiction between compaction density and particle strength

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electrode structure are assigned different particle sizes - larger macroparticles in certain zones provide structural framework and compaction, while smaller microparticles in other zones provide flexibility and crack prevention. This local differentiation allows simultaneous achievement of high compaction density and resistance to rolling-induced cracking

Inventive Principle:

Principle #3Local quality

2Reliability

If rolling pressure is increased to prevent short circuit, then electrical safety is improved, but particle cracking increases

Engineering Contradiction:

Improveelectrical safetyVSAvoidparticle strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Secondary microparticles are introduced beforehand as a cushioning phase that absorbs rolling pressure and prevents direct transmission of stress to secondary macroparticles. This beforehand cushioning allows sufficient rolling pressure to be applied for electrical safety without causing particle cracking, as the microparticles act as a protective buffer

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Quantity of substance

If nickel content is increased to ensure high capacity, then battery capacity is improved, but thermal stability deteriorates

Engineering Contradiction:

Improvebattery capacityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The particle size distribution parameter is changed to create a bimodal mixture of macroparticles and microparticles. This parameter change indirectly stabilizes the high-nickel cathode material by reducing mechanical stress and cracking during processing, thereby preserving thermal stability while maintaining high capacity from the nickel-rich composition

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4287302B1Cathode for lithium secondary battery, and cathode and lithium secondary battery including same

Publication Date: 2026.04.01 LG ENERGY SOLUTION LTD

Figure 1~2
Figure 3

AI summary

The present disclosure discloses a positive electrode for a lithium secondary battery comprising a positive electrode active material layer comprising positive electrode active material secondary macroparticles and secondary microparticles having different average particle sizes to allow sufficiently high rolling pressure when manufacturing the electrode.