Coated Lithium Metal Oxide Active Material for High Voltage Batteries
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Solution Overview
Problem
Conventional methods for improving energy density in rechargeable electrochemical elements, such as lithium ion secondary batteries, face challenges in maintaining cycle life and thermostability due to increased charging voltage, leading to poor charge-discharge cycle characteristics and electrolyte decomposition.
Innovation Solution
The method involves covering lithium-containing metal oxide particles with metal oxide particle groups using a liquid phase deposition process, involving a metal-fluoro complex and lithium salt, which enhances adhesiveness and inhibits electrolyte decomposition, thereby improving cycle characteristics and thermostability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If charging voltage is increased to raise energy density, then energy density is improved, but cycle life and storage characteristics deteriorate due to electrolyte decomposition
Solution Approach 1:
A coating layer comprising metal oxide particle groups is introduced as an intermediary between the positive electrode active material and the electrolyte solution. This coating layer prevents direct contact and harmful interactions at high voltage while allowing lithium ion transport, thus enabling high energy density operation without sacrificing cycle life
Solution Approach 2:
The charging voltage is increased from conventional 4.2V to 4.6V or higher to utilize the high potential sections of the positive electrode active material. This parameter change raises energy density but would normally cause electrolyte decomposition, unless the protective coating is applied
2Use of energy by moving object
If charging voltage is increased to raise energy density, then energy density is improved, but thermostability deteriorates due to lower exothermic peak temperature
Solution Approach 1:
The metal oxide particle groups in the coating layer act as a thermal barrier and protective intermediary, preventing direct thermal interaction between the positive electrode active material and the electrolyte solution. This maintains thermostability even when operating at higher charging voltages that would normally reduce exothermic peak temperature
3Temperature
If conventional coating methods are applied to prevent electrolyte decomposition, then thermostability is improved, but charge-discharge cycle characteristics remain poor due to high resistance film formation
Solution Approach 1:
Instead of forming a continuous uniform coating, the invention uses discrete metal oxide particle groups distributed on the surface. This local quality approach provides protection where needed while maintaining porosity and lithium ion transport pathways, preventing high resistance film formation
Solution Approach 2:
The coating layer comprises particle groups with inherent porosity between particles, allowing efficient lithium ion diffusion while providing protective coverage. This porous structure prevents the formation of dense high-resistance films that plague conventional coating methods
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 approach results in improved charge-discharge cycle characteristics and energy density, particularly at higher temperatures, by preventing electrolyte decomposition and maintaining lithium integrity, thus extending battery life and performance.
Implementation Method 1
MFx(x-2n)+nH2O=MOn+xF−+2nH+
Implementation Method 2
immersing the lithium-containing metal oxide particles in an aqueous solution containing a metal-fluoro complex and a lithium salt
Implementation Method 3
the aqueous solution contains a lithium salt, elution of lithium from the lithium-containing metal oxide into the aqueous solution is inhibited
Data Source
AI summary
There is provided a method of making an active material with satisfactory cycle characteristics. The method of making an active material according to the invention comprises contacting an aqueous solution containing a metal-fluoro complex and lithium salt with lithium-containing metal oxide particles.