Substituted Lithium Titanium Oxide Negative Electrode for Battery Cycle Life

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Solution Overview

Problem

Conventional nonaqueous electrolyte secondary batteries suffer from deterioration of the positive electrode active material during discharge, leading to poor cycle characteristics due to irreversible capacity issues.

Innovation Solution

A nonaqueous electrolyte secondary battery design featuring a positive electrode with a lithium-containing transition metal oxide having a layered crystalline structure and a negative electrode with a lithium-containing transition metal oxide obtained by substituting Ti in lithium-containing titanium oxide with other elements, such as Mn, Fe, V, or B, which enhances the irreversible capacity rate and ensures discharge ends by negative electrode limitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional nonaqueous electrolyte secondary battery uses a positive electrode active material with layered structure and Li4Ti5O12 as negative electrode, then the battery can operate with good initial performance, but the positive electrode active material deteriorates during discharge leading to poor cycle characteristics

Engineering Contradiction:

Improvecycle characteristicsVSAvoidpositive electrode active material stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent modifies the chemical composition parameters of the negative electrode active material by substituting Ti elements with other metal elements (Mn, Fe, V, B, etc.) in controlled amounts. This changes the irreversible capacity rate parameter to be greater than that of conventional Li4Ti5O12, which shifts the discharge limitation from positive electrode to negative electrode, thereby preventing positive electrode deterioration and improving cycle characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite negative electrode active material by combining Li4Ti5O12 with other metal elements to form a substituted lithium-containing titanium oxide. This composite material has enhanced irreversible capacity rate compared to pure Li4Ti5O12, enabling the battery to operate under negative electrode limitation and protect the positive electrode from deterioration during cycling.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the irreversible capacity rate of the negative electrode is smaller than that of the positive electrode, then the battery can achieve high initial capacity, but the positive electrode potential decreases during discharge causing positive electrode limitation and material deterioration

Engineering Contradiction:

Improvedischarge capacityVSAvoidcycle characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent increases the irreversible capacity rate parameter of the negative electrode by substituting Ti with other metal elements. This parameter change ensures that the negative electrode has greater irreversible capacity than the positive electrode, causing discharge to be limited by the negative electrode rather than the positive electrode, thereby preventing positive electrode deterioration while maintaining high capacity.

Inventive Principle:

Principle #35Parameter changes

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

This configuration improves cycle characteristics by preventing potential drop in the positive electrode during discharge, suppressing deterioration of the positive electrode active material and maintaining high discharging capacity over multiple cycles.

Implementation Method 1

a negative electrode capable of absorbing and releasing lithium

Methodology Applied

Scientific EffectAbsorption (physical): Absorption (physical)

Implementation Method 2

a positive electrode capable of absorbing and releasing lithium

Methodology Applied

Scientific EffectAbsorption (physical): Absorption (physical)

Implementation Method 3

a negative electrode active material composed of a lithium-containing transition metal oxide obtained by substituting some of Ti element of a lithium-containing titanium oxide having a spinel crystalline structure with one or more element different from Ti

Methodology Applied

Scientific EffectElectrochemical reactions: Redox Reactions

Data Source

PatentUS10103382B2Nonaqueous electrolyte secondary battery

Publication Date: 2018.10.16 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A nonaqueous electrolyte secondary battery disclosed in the present application includes: a positive electrode capable of absorbing and releasing lithium, containing a positive electrode active material composed of a lithium-containing transition metal oxide having a layered crystalline structure; and a negative electrode capable of absorbing and releasing lithium, containing a negative electrode active material composed of a lithium-containing transition metal oxide obtained by substituting some of Ti element of a lithium-containing titanium oxide having a spinel crystalline structure with one or more element different from Ti, wherein a retention of the negative electrode is set to be greater than a retention of the positive electrode, and an irreversible capacity rate of the negative electrode is set to be greater than an irreversible capacity rate of the positive electrode, whereby a discharge ends by negative electrode limitation.