AlF3 Coated LiNi0.5Mn1.5O4 Cathode for High-Voltage Stability

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Solution Overview

Problem

Lithium ion batteries using LiNi0.5Mn0.5O4 cathode active materials face decreased cycle performance due to electrolyte decomposition at high charge voltages, which affects their overall efficiency.

Innovation Solution

A cathode active material is developed by coating aluminum fluoride (AlF3) layers on LiNi0.5Mn1.5O4 particles, with a uniform thickness of 8-20 nanometers, to enhance cycle performance and prevent electrolyte decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If LiNi0.5Mn0.5O4 is charged to high voltage, then specific capacity is improved, but electrolyte decomposition occurs leading to decreased cycle performance

Engineering Contradiction:

Improvespecific capacityVSAvoidcycle performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

An aluminum fluoride (AlF3) coating layer is applied as an intermediary between the LiNi0.5Mn0.5O4 cathode material and the electrolyte. This coating layer acts as a protective barrier that prevents direct contact and chemical reaction between the electrolyte and the cathode surface, thereby eliminating electrolyte decomposition while allowing lithium ion transport to maintain high specific capacity and improve cycle performance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the surface chemical composition and physical properties of the cathode material by applying an AlF3 coating. This modifies the surface electrochemical characteristics, creating a stable interface that resists electrolyte decomposition at high voltages while maintaining good lithium ion conductivity, thus resolving the contradiction between high capacity and cycle stability

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 AlF3 coating significantly improves the cycle performance and discharge capacity of lithium ion batteries by preventing electrolyte decomposition and maintaining electrochemical stability at high charge voltages.

Implementation Method 1

The decomposition of the electrolytes results in a decrease of cycle performances of the lithium ion batteries... coating aluminum fluoride (AlF3) layers on LiNi0.5Mn1.5O4 particles... preventing electrolyte decomposition

Methodology Applied

Scientific EffectChemical barrier protection:

Data Source

PatentUS9362016B2Cathode active material, method for making the same and lithium ion battery using the same

Publication Date: 2016.06.07 HON HAI PRECISION INDUSTRY CO LTD

AI summary

A cathode active material of a lithium ion battery includes a number of LiNi0.5Mn1.5O4 particles and an AlF3 layer coated on a surface of the LiNi0.5Mn1.5O4 particles. A method for making the cathode active material is provided. In the method, a number of LiNi0.5Mn1.5O4 particles are provided. The LiNi0.5Mn1.5O4 particles are added to a trivalent aluminum source solution to form a solid-liquid mixture. A fluorine source solution is put into the solid-liquid mixture to react and form an AlF3 layer coated on the surface of the LiNi0.5Mn1.5O4 particles. The coated LiNi0.5Mn1.5O4 particles are heat treated to form the cathode active material. A lithium ion battery including the cathode active material is also provided.