High-Ni Cathode Electrolyte Design for Low-Impedance Cycle Stability

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Solution Overview

Problem

Non-aqueous electrolyte secondary batteries with high Ni content in the positive electrode active material face issues of increased impedance and deteriorated cycle characteristics due to unstable crystal structures and metal leaching, which are exacerbated by the use of fluorosulfonic acid salts and carbon nanotubes.

Innovation Solution

Combining a lithium-transition metal composite oxide with a high Ni content and carbon nanotubes in the positive electrode, along with a non-aqueous electrolyte containing a fluorosulfonic acid salt, forms a robust surface film that stabilizes the structure and reduces impedance, enhancing cycle characteristics at high rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the proportion of Ni in the lithium-transition metal composite oxide is increased to achieve high capacity, then the energy density is improved, but the crystal structure becomes unstable and impedance increases

Engineering Contradiction:

Improveenergy densityVSAvoidcycle characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

Aluminum oxide (Al2O3) coating is applied as an intermediary layer on the surface of the high-Ni composite oxide particles. This coating layer acts as a protective barrier that stabilizes the crystal structure, prevents metal leaching, and suppresses impedance increase during charge-discharge cycles, thereby improving cycle characteristics while maintaining high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite structure combining the lithium-transition metal composite oxide (with high Ni content) and aluminum oxide coating. This composite material approach allows the core high-Ni material to provide high capacity while the outer Al2O3 layer provides structural stability and protects against degradation, resolving the contradiction between energy density and reliability

Inventive Principle:

Principle #40Composite materials

2Reliability

If fluorosulfonic acid salt is added to the non-aqueous liquid electrolyte to improve cycle characteristics, then the positive electrode stability is improved, but the viscosity of the liquid electrolyte increases and high-rate characteristics deteriorate

Engineering Contradiction:

Improvecycle characteristicsVSAvoidhigh-rate characteristics

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The invention optimizes the concentration parameter of fluorosulfonic acid salt in the non-aqueous liquid electrolyte to a specific range (0.01-5 mass%, preferably 0.05-2 mass%). By precisely controlling this parameter, the invention achieves sufficient cycle characteristic improvement while minimizing the viscosity increase that would harm high-rate characteristics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fluorosulfonic acid salt primarily acts at the positive electrode-electrolyte interface where it forms a protective film, providing local stabilization without significantly affecting the bulk electrolyte properties. This localized action allows cycle characteristic improvement with minimal impact on overall electrolyte viscosity and high-rate performance

Inventive Principle:

Principle #3Local quality

3Reliability

If carbon nanotubes are introduced into the positive electrode to improve high-rate cycle characteristics, then the high-rate performance is improved, but the reaction resistance increases and impedance increases

Engineering Contradiction:

Improvehigh-rate cycle characteristicsVSAvoidimpedance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention combines carbon nanotubes with aluminum oxide-coated high-Ni composite oxide particles in the positive electrode. The Al2O3-coated particles provide low reaction resistance and stable structure, while carbon nanotubes provide conductive networks. The synergistic effect of this combination improves high-rate cycle characteristics without the significant impedance increase that would result from carbon nanotubes alone

Inventive Principle:

Principle #5Merging (Combining)

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

The combination effectively suppresses impedance increase and improves cycle characteristics at high rates by stabilizing the composite oxide structure and maintaining efficient lithium ion absorption and release, despite the high Ni content.

Implementation Method 1

a non-aqueous electrolyte containing a fluorosulfonic acid salt... forms a robust surface film that stabilizes the structure

Methodology Applied

Scientific EffectSurface film formation: Deposition (physical)

Implementation Method 2

reversible absorption and release of Li ions... maintaining efficient lithium ion absorption and release

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS12580191B2Non-aqueous electrolyte secondary battery

Publication Date: 2026.03.17 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A non-aqueous liquid electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, in which the positive electrode includes a positive electrode active material, and a carbon nanotube, the positive electrode active material includes a lithium-transition metal composite oxide containing Ni, a proportion of Ni in metal elements other than Li in the lithium-transition metal composite oxide is 80 atm % or more, and the non-aqueous electrolyte includes a fluorosulfonic acid salt.