Lithium Secondary Battery Cathode with Reversible Lithium-Titanium Oxide

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Solution Overview

Problem

Lithium composite oxide cathode materials in secondary batteries face stability and lifespan issues due to reactions with air and electrolytes during charging and discharging, leading to deteriorated performance and operational stability.

Innovation Solution

Incorporating a reversible lithium-titanium oxide phase formed on the surface of lithium composite oxide particles with a high nickel molar ratio, along with TiO2 particles, to enhance structural stability and capacity, and using a specific chemical composition and processing methods to maintain stability and improve lithium ion mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high nickel content lithium composite oxide is used to increase capacity, then battery capacity is improved, but structural stability and lifespan are deteriorated

Engineering Contradiction:

Improvebattery capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent uses a composite material system consisting of lithium composite oxide particles (with high nickel content for capacity) coated with titanium oxide. This composite structure allows the inner lithium composite oxide to provide high capacity while the outer titanium oxide layer provides structural stability and resistance to degradation, resolving the contradiction between capacity and stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies different material properties to different regions: the core lithium composite oxide particles provide high nickel content for capacity, while the surface coating of titanium oxide provides stability. This local differentiation of material quality allows each region to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If high nickel content lithium composite oxide is used to increase capacity, then battery capacity is improved, but battery lifespan is deteriorated

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifespan

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The composite structure of lithium composite oxide core with titanium oxide coating allows the high-nickel core to maintain capacity while the protective titanium oxide shell prevents degradation during cycling, thereby extending battery lifespan without sacrificing capacity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The titanium oxide coating is applied in advance to the lithium composite oxide particles before battery operation. This pre-formed protective layer cushions the high-nickel material against harmful reactions with electrolytes and oxygen during charging and discharging, preventing degradation before it occurs and extending battery life.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If lithium composite oxide is exposed to air or reacts with electrolyte to achieve initial formation, then battery activation is completed, but stability and operational reliability are deteriorated

Engineering Contradiction:

Improvebattery formationVSAvoidoperational stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The titanium oxide coating creates an inert protective environment around the lithium composite oxide particles, shielding them from harmful reactions with oxygen and electrolyte during formation and operation. This allows safe exposure to air during manufacturing while preventing degradation during battery operation.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The titanium oxide layer acts as an intermediary between the lithium composite oxide and the external environment (air and electrolyte). It mediates the interaction by allowing necessary formation reactions while blocking harmful degradation reactions, thus enabling both formation completion and long-term stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 significantly improves the lifespan and capacity of lithium secondary batteries by forming a reversible lithium-titanium oxide phase, which enhances structural stability and power performance, particularly in high voltage regions, while maintaining high nickel content for increased capacity.

Implementation Method 1

a reversible lithium-titanium oxide selectively present in a charging region of 4.1 V or more and less than 4.3 V

Methodology Applied

Scientific EffectPhase transition: Phase Change

Implementation Method 2

The lithium secondary battery may include an electrode assembly including a cathode, an anode and a separation layer, and an electrolyte immersing the electrode assembly

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentEP4057381A1Lithium secondary battery

Publication Date: 2022.09.14 SK ON CO LTD

Figure 1~2

AI summary

A lithium secondary battery includes a cathode including a cathode active material, and an anode facing the cathode. The cathode active material includes a lithium composite oxide particle having a nickel molar ratio of 0.8 or more among elements other than lithium and oxygen, and a reversible lithium-titanium oxide selectively present in a charging region of 4.1 V or more and less than 4.3 V. Life-span stability is improved by the reversible lithium-titanium oxide at a high-voltage region.