High-Nickel Cathode Surface Coating Against Resistance Buildup

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Solution Overview

Problem

Existing secondary batteries do not achieve optimal battery characteristics due to insufficient electrochemical performance, particularly in the positive electrode active material layer, leading to increased electric resistance and decreased capacity upon repeated charging and discharging.

Innovation Solution

The positive electrode active material layer includes lithium composite oxide with a high nickel content (80-100 mol%) and a covering part made of lithium fluoroborate (LiBOF2) to protect the surface, suppressing oxidative decomposition and maintaining low electric resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high nickel content lithium composite oxide is used in the positive electrode active material layer, then battery capacity and energy density are improved, but electric resistance increases and battery characteristic deteriorates upon repeated charging and discharging

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery characteristic upon repeated charging and discharging

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent uses a composite material structure where lithium composite oxide particles with high nickel content (80-100 mol%) are coated with a protective film containing lithium fluoroborate. This composite structure allows the high-nickel core to provide high capacity while the protective coating prevents degradation and maintains low resistance over repeated cycles, thus resolving the contradiction between capacity and reliability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the chemical composition parameters of the protective coating by incorporating lithium fluoroborate, which fundamentally alters the surface properties of the positive electrode active material. This parameter change in the coating composition prevents oxidative decomposition and maintains electrical conductivity, allowing the high-nickel material to maintain its performance over repeated charging and discharging cycles

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If high nickel content lithium composite oxide is used to increase energy density, then battery performance is improved, but oxidative decomposition occurs on the particle surface leading to increased electric resistance

Engineering Contradiction:

Improveenergy densityVSAvoidoxidative decomposition and electric resistance

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful oxidative environment into a beneficial protective layer by allowing controlled formation of lithium fluoroborate on the particle surface. This layer, formed through the interaction of lithium composite oxide with fluoroborate-containing compounds, transforms the potentially harmful oxidative decomposition into a protective mechanism that actually prevents further degradation and maintains low electric resistance

Inventive Principle:

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

Solution Approach 2:

The lithium fluoroborate coating creates an inert protective environment around the high-nickel lithium composite oxide particles, shielding them from oxidative decomposition. This inert barrier prevents direct contact between the reactive high-nickel material and the electrolyte, thereby maintaining low electric resistance and stable performance while preserving the high energy density benefits

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

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 solution enhances battery performance by preventing the formation of resistance components and maintaining battery capacity through electrochemical protection, ensuring stable charge transfer reactions.

Implementation Method 1

suppressing oxidative decomposition and maintaining low electric resistance

Methodology Applied

Scientific EffectOxidative decomposition: Oxidation

Implementation Method 2

analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS)

Methodology Applied

Scientific EffectTime-of-flight secondary ion mass spectrometry: Time of Flight

Data Source

PatentUS20250364553A1Secondary battery

Publication Date: 2025.11.27 MURATA MFG CO LTD

AI summary

A secondary battery is provided and includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes positive electrode active material particles. The positive electrode active material particles each include a center part and a covering part. The center part includes a lithium composite oxide. The covering part is provided on a surface of the center part. The lithium composite oxide has a layered rock-salt crystal structure, and includes lithium, nickel, and another element as constituent elements. Where a sum of a content of nickel in the lithium composite oxide and a content of the other element in the lithium composite oxide is taken as 100 parts by mole, the content of nickel is greater than or equal to 80 parts by mole and less than or equal to 100 parts by mole. Based on an analysis of the positive electrode active material layer in a depth direction by time-of-flight secondary ion mass spectrometry, a first negative secondary ion derived from NiO2− and a second negative secondary ion derived from LiBO2F− are detectable, and a first depth profile and a second depth profile are acquirable.