Bimodal LCO Cathode Composition for High-Voltage Cycle Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium-ion battery cathode active materials, particularly lithium cobalt oxide (LCO), face degradation and reduced cycle stability at high voltages due to electrochemical and crystallographic stress on smaller particles, leading to increased aging rates.

Innovation Solution

A cathode active material comprising a blend of lithium cobalt oxide (LCO) particles with a bimodal particle size distribution and nickel manganese cobalt (NMC) particles, which provides increased crystallographic and electrochemical stability at high potentials while maintaining energy density, by combining larger LCO core particles with smaller NMC filler particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If smaller LCO particles are used to increase surface area and reaction kinetics, then energy density and power output are improved, but crystallographic stress and aging rate increase leading to reduced cycle stability

Engineering Contradiction:

Improveenergy densityVSAvoidcycle stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent creates a composite cathode material consisting of LCO particles embedded in an NMC matrix. The NMC component provides structural stability and resistance to crystallographic stress, while the LCO particles contribute high energy density. This composite structure allows the battery to achieve both high productivity (energy density) and high reliability (cycle stability) by combining the advantages of both materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating a heterogeneous structure where different regions have different properties. The LCO particles are distributed within the NMC matrix, with each particle size optimized for its local function. Smaller LCO particles provide high surface area for fast kinetics while being protected by the surrounding NMC matrix that absorbs stress and prevents degradation.

Inventive Principle:

Principle #3Local quality

2Power

If higher voltage operation is implemented to increase energy density, then power output is improved, but cathode material degradation accelerates reducing battery longevity

Engineering Contradiction:

Improvepower outputVSAvoidbattery longevity

Core Design Contradiction:

PowerVSDuration of action of stationary object

Solution Approach 1:

The NMC matrix acts as a protective framework that enables high voltage operation of LCO particles without suffering from the same degradation mechanisms. The NMC material has inherent stability at high voltages, allowing the composite to operate at elevated potentials (4.3-4.4V) while maintaining longevity. This resolves the contradiction between power output and battery longevity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The NMC matrix serves as an intermediary between the high-voltage LCO particles and the electrolyte/other components. It mediates the high voltage stress, preventing direct degradation of the LCO structure while still allowing efficient electron and ion transport. This intermediary role protects the cathode material from degradation during high voltage operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250096236A1Cathode design and composition for lithium-ion batteries

Publication Date: 2025.03.20 APPLE INC

AI summary

This disclosure relates generally to battery cells, and more particularly, cathode active materials for use in lithium-ion battery cells.