Lithium Battery Safety via Phosphate Coating

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Solution Overview

Problem

Lithium secondary batteries face safety issues during overcharging due to exothermic reactions, which can lead to heat generation and potential explosions, especially in batteries with larger volumes where the reaction between active materials and electrolytes is more severe.

Innovation Solution

Incorporating a non-aqueous organic electrolyte with a specific additive, such as triphenyl phosphate, that forms a thin film on the cathode, reducing the exothermic reaction and enhancing safety by suppressing the interface reaction between the active material and electrolyte, thereby controlling heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the battery volume is increased to achieve higher energy density, then the energy storage capacity is improved, but the exothermic reaction during overcharging becomes more severe leading to safety issues

Engineering Contradiction:

Improveenergy storage capacityVSAvoidexothermic reaction severity

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

A coating layer comprising a phosphate compound is formed on the cathode active material surface to act as an intermediary barrier. This coating layer suppresses the exothermic reaction between the cathode active material and electrolyte during overcharging, while maintaining the battery's energy storage capacity across various volumes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface properties of the cathode active material are modified by forming a coating layer with specific phosphate compounds. This changes the chemical and thermal parameters of the cathode surface, reducing its reactivity with the electrolyte and suppressing exothermic reactions during overcharging conditions

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the battery volume is increased to achieve higher energy density, then the energy storage capacity is improved, but the heat generation during overcharging increases leading to potential explosions

Engineering Contradiction:

Improveenergy storage capacityVSAvoidheat generation

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The phosphate compound coating layer serves as a thermal barrier and reaction suppressor between the cathode active material and electrolyte. It effectively reduces heat generation during overcharging by preventing direct exothermic reactions, thereby improving battery safety without compromising energy storage capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The coating layer transforms the potentially harmful direct contact and exothermic reaction between cathode material and electrolyte into a controlled interface reaction. This converts the harmful heat generation into a beneficial protective mechanism that suppresses thermal runaway while maintaining battery performance

Inventive Principle:

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

3Reliability

If a coating layer comprising a phosphate compound is formed on the cathode active material, then the exothermic reaction is suppressed and safety is improved, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvebattery safetyVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The phosphate compound coating is formed on the cathode active material surface before battery assembly through conventional coating methods. This preliminary action ensures that the safety-enhancing coating is already in place before the battery enters service, preventing exothermic reactions from the outset without requiring additional safety mechanisms during operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating formation process utilizes conventional coating parameters and phosphate compounds that can be integrated into existing manufacturing workflows. By optimizing coating thickness and composition, the process achieves effective reaction suppression while minimizing additions to the manufacturing complexity

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

The solution effectively improves safety during overcharging by reducing heat values and preventing explosions in lithium secondary batteries with volumes ranging from 16 cm3 to 84 cm3, while maintaining cycle-life characteristics.

Implementation Method 1

forms a thin film on the cathode

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

the additive... forms a thin film on the cathode, reducing the exothermic reaction

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS20230109373A1Lithium secondary battery

Publication Date: 2023.04.06 SAMSUNG SDI CO LTD

AI summary

The present invention relates to a lithium secondary battery, the lithium secondary battery comprising: a cathode containing a cathode active material, an anode containing an anode active material; and an electrolyte containing a non-aqueous organic solvent, a lithium salt, and an additive represented by Chemical Formula 1, wherein the lithium secondary battery has a volume of 16 cm3 to 84 cm3.