Nonaqueous Electrolyte Battery Overcharge Heat Suppression

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Solution Overview

Problem

Nonaqueous electrolyte batteries face safety issues due to rapid heat generation during overcharge, primarily caused by the imbalance in positive and negative electrode capacities leading to excessive potential decrease and side reactions with the electrolyte.

Innovation Solution

A nonaqueous electrolyte battery design featuring a titanium oxide negative electrode with specific surface atom ratios and a nickel-cobalt-manganese composite oxide positive electrode, where the nickel-cobalt-manganese composite oxide composition and the surface state of the titanium oxide prevent excessive lithium insertion and oxidative decomposition, maintaining thermal stability and suppressing heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the positive electrode capacity is made larger than the negative electrode capacity to suppress potential increase and heat generation, then thermal stability is improved, but the negative electrode potential decreases rapidly during over-charge causing safety issues

Engineering Contradiction:

Improveheat generationVSAvoidsafety

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent optimizes the capacity ratio parameter p/n to be within 1.05 to 1.30, and controls the negative electrode potential to remain within 0.05V to 0.20V below the positive electrode potential during over-charge. These precise parameter ranges resolve the contradiction by preventing both excessive heat generation and dangerous potential drops.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements potential difference monitoring between positive and negative electrodes during charging. By maintaining the negative electrode potential within a specific range relative to the positive electrode, the system provides feedback control that prevents both thermal runaway and safety hazards from excessive potential decrease.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the negative electrode capacity is made lower than the positive electrode capacity to control over-charge, then positive electrode potential stability is improved, but side reactions between negative electrode surface and electrolyte are accelerated

Engineering Contradiction:

Improvepositive electrode potential stabilityVSAvoidside reactions and heat generation

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential difference between electrodes into a beneficial control mechanism. By maintaining the negative electrode potential slightly below the positive electrode potential, the system uses this potential relationship to prevent side reactions and heat generation, turning what could be a harmful effect into a protective mechanism.

Inventive Principle:

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

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 battery effectively suppresses heat generation and maintains safety by stabilizing the negative electrode potential and reducing oxidative decomposition, even in overcharged states, thereby enhancing overall safety and performance.

Implementation Method 1

the nickel-cobalt-manganese composite oxide composition and the surface state of the titanium oxide prevent excessive lithium insertion and oxidative decomposition

Methodology Applied

Scientific EffectOxidative decomposition: Oxidation

Implementation Method 2

a side reaction between the surface of the negative electrode and an electrolyte solution to be accelerated

Methodology Applied

Scientific EffectElectrochemical reaction: Electrolyte

Implementation Method 3

prevent excessive lithium insertion

Methodology Applied

Scientific EffectLithium insertion: Absorption (physical)

Implementation Method 4

stabilizing the negative electrode potential

Methodology Applied

Scientific EffectElectrode potential stabilization:

Implementation Method 5

heat may be generated, accompanied with the side reaction. The heat increases the temperature of the interior of the nonaqueous electrolyte battery

Methodology Applied

Scientific EffectHeat generation: Joule Heating

Implementation Method 6

maintaining thermal stability and suppressing heat generation

Methodology Applied

Scientific EffectThermal stability:

Data Source

PatentEP2980886B1Nonaqueous electrolyte battery and battery pack

Publication Date: 2019.01.16 KK TOSHIBA

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AI summary

According to one embodiment, there is provided a nonaqueous electrolyte battery (100). The nonaqueous electrolyte battery (100) includes a negative electrode (2), a positive electrode (3), and a nonaqueous electrolyte. An Li-atom abundance ratio ALi, Ti-atom abundance ratio ATi, and C-atom abundance ratio AC of a surface of the negative electrode (2) satisfy inequalities 2 ≤ AC/ATi ≤ 10, and 1.0 ≤ ALi/AC ≤ 1.5. The positive electrode (3) includes a nickel-cobalt-manganese composite oxide represented by a composition formula Li1-aNixCoyMnzO2. Subscripts x, y, and z satisfy an inequality 0.1 ≤ x/(y + z) ≤ 1.3, and subscript a satisfies an inequality 0 ≤ a ≤ 1. A ratio p/n of a capacity p of the positive electrode (3) to a capacity n of the negative electrode (2) is within a range of 1.2 to 2.