Positive Electrode Active Material With Phosphate-Filled Cracks

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Solution Overview

Problem

Existing lithium-ion secondary batteries face challenges with high capacity, cycle performance, and safety issues, particularly due to cobalt dissolution at high voltages, and require improved positive electrode active materials with enhanced productivity.

Innovation Solution

A positive electrode active material comprising a first substance with a crack containing cobalt, manganese, nickel, lithium, oxygen, magnesium, and fluorine, and a second substance of phosphorus and oxygen, where phosphorus concentration is higher and transition metal concentration is lower within the crack, providing a layered rock-salt crystal structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high voltage charging is used to increase capacity, then energy density is improved, but cobalt dissolution occurs and cycle performance deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidcycle performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses a composite material structure where a phosphate-containing substance (such as Li3PO4, Li2SiO3, or other phosphate compounds) is formed on the surface of the positive electrode active material particles. This composite structure combines the high capacity characteristics of layered rock-salt crystal structure materials with the protective properties of phosphate coatings, enabling high voltage charging (4.3V or higher) without cobalt dissolution, thus achieving both high energy density and excellent cycle performance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The phosphate-containing substance acts as an intermediary protective layer between the cobalt-containing positive electrode active material and the electrolyte. This intermediate layer prevents direct contact and chemical reactions that would otherwise cause cobalt dissolution at high voltages, while still allowing lithium ion transport, thus protecting the electrode material during high voltage charging cycles

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If cobalt content is increased to improve capacity, then energy density is improved, but cobalt dissolution and safety issues worsen

Engineering Contradiction:

ImprovecapacityVSAvoidcobalt dissolution

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite structure where phosphate-containing substances are integrated with cobalt-containing layered rock-salt crystal structure materials. This composite approach allows the cobalt-rich material to provide high capacity while the phosphate component provides protective functionality, preventing cobalt dissolution even when cobalt content is high

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent converts the potential harm of cobalt dissolution into a benefit by using phosphate compounds that can form protective surface layers. The phosphate-containing substance, when formed on the particle surfaces, transforms from a simple additive into a protective barrier that prevents cobalt release, thus converting what would be a harmful effect into a protective mechanism

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Use of energy by moving object

If particle density is increased to improve energy density, then capacity is improved, but crack formation increases and cycle performance deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidcycle performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by forming a phosphate-containing substance coating on the particle surfaces before cracks can develop and propagate. This protective layer acts as a cushion that absorbs stress during charging and discharging cycles, preventing crack formation and propagation even in densely packed particles, thus maintaining both high energy density and good cycle performance

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the surface properties of the particles by introducing phosphate-containing substances, which modifies the surface chemistry and mechanics. This parameter change in surface composition provides both chemical protection against dissolution and mechanical protection against crack formation, allowing particles to maintain structural integrity under high density conditions

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12548762B2Positive electrode active material, positive electrode, secondary battery, and method for manufacturing positive electrode

Publication Date: 2026.02.10 SEMICON ENERGY LAB CO LTD

AI summary

A positive electrode active material, which has a high capacity and excellent charge and discharge cycle performance, for a lithium-ion secondary battery is provided. Alternatively, a positive electrode active material that inhibits a decrease in capacity in charge and discharge cycles when used in a lithium-ion secondary battery is provided. Alternatively, a high-capacity secondary battery is provided. Alternatively, a highly safe or reliable secondary battery is provided. The positive electrode active material contains a first substance including a first crack and a second substance positioned inside the first crack. The first substance contains one or more of cobalt, manganese, and nickel, lithium, oxygen, magnesium, and fluorine. The second substance contains phosphorus and oxygen.