Multinary Oxide Coated Electrode Active Material for High-Voltage Stability

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Solution Overview

Problem

Current lithium secondary battery cathode active materials face issues with structural instability and thermal safety due to rapid oxygen liberation during high-voltage charging, leading to potential battery explosions, and existing methods fail to effectively control the exothermic reaction temperature and oxygen decomposition.

Innovation Solution

A multinary oxide coating layer comprising aluminum (Al), phosphorus (P), and a halogen element is formed on the surface of electrode active material particles, enhancing structural stability and bonding forces, thereby inhibiting oxygen liberation and improving thermal safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If charge voltage is increased to improve capacity, then capacity increases, but structural stability deteriorates and thermal safety drops

Engineering Contradiction:

ImprovecapacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

A coating layer comprising Al, P, and halogen elements is formed on the surface of the cathode active material before high-voltage charging. This preliminary protective action prevents structural degradation and oxygen liberation that would otherwise occur during high-voltage operation, enabling capacity improvement without compromising structural stability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating layer acts as an intermediary between the cathode active material and the harsh high-voltage charging environment. It mediates the interaction by providing a protective barrier that prevents direct contact between the electrolyte and the cathode material surface, thereby maintaining structural stability during high-capacity charging

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If charge voltage is increased to improve capacity, then capacity increases, but thermal safety deteriorates due to oxygen liberation

Engineering Contradiction:

ImprovecapacityVSAvoidthermal safety

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The coating layer is applied in advance to counteract the harmful effect of oxygen liberation. By forming this protective barrier before charging, the invention prevents the decomposition and liberation of oxygen from the cathode active material during high-voltage charging, thereby maintaining thermal safety while achieving high capacity

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The coating layer containing halogen elements transforms the potential harmful oxygen liberation into a beneficial protective mechanism. The halogen elements in the coating layer have high affinity for oxygen and can trap liberated oxygen, converting what would be a harmful thermal runaway trigger into a controlled process that maintains battery safety

Inventive Principle:

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

3Area of stationary object

If particle size is reduced to increase surface area, then surface area increases, but manufacturing complexity increases

Engineering Contradiction:

Improvesurface areaVSAvoidmanufacturing complexity

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The coating formation process is merged with the existing cathode material preparation process. The coating precursors are mixed with the cathode active material particles before sintering, combining two steps (material preparation and coating application) into one integrated manufacturing process, thereby increasing surface area without significantly increasing manufacturing complexity

Inventive Principle:

Principle #5Merging (Combining)

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 multinary oxide coating layer improves the battery's structural stability and thermal safety, allowing for high-voltage charging/discharging while preventing rapid temperature increases and heat emissions, resulting in enhanced capacity, service life, and safety.

Implementation Method 1

such cathode active materials in a charged state show a rapid drop in bonding force between metal ions and oxygen atoms

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

oxygen is decomposed and liberated from such unstable cathode active materials

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS7727670B2Electrode active material with multi-element based oxide layers and preparation method thereof

Publication Date: 2010.06.01 LG ENERGY SOLUTION LTD

AI summary

Disclosed is an electrode active material comprising: (a) electrode active material particles capable of lithium intercalation/deintercalation; and (b) a multinary oxide coating layer partially or totally formed on the surface of the electrode active material particles, the multinary oxide coating layer comprising Al, P and a halogen element. A method for preparing the electrode active material, an electrode using the electrode active material, and an electrochemical device comprising the electrode, preferably a lithium secondary battery, are also disclosed. The electrode active material comprising a multinary oxide coating layer has improved structural stability and thermal safety, and thus can provide an electrochemical device having high capacity, long service life and excellent safety.