Lithium-Intercalatable Phosphate Coating on Positive Active Material
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Solution Overview
Problem
Lithium ion batteries face challenges with high-voltage positive active materials that have low initial efficiency and poor high-temperature stability, leading to reduced capacity and lifespan due to side reactions with the electrolyte.
Innovation Solution
A positive active material is developed by incorporating a lithium-intercalatable phosphate compound, such as MoOPO4, TiOPO4, VOPO4, or TaOPO4, on a lithium-containing oxide, which improves initial efficiency and high-temperature stability by forming strong covalent bonds and reducing irreversible lithium ion intercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-voltage positive active materials are used to increase capacity, then energy density is improved, but initial efficiency decreases and high-temperature stability deteriorates
Solution Approach 1:
The patent applies composite materials by combining lithium-containing oxide particles with a phosphate compound coating layer. The phosphate compound (such as MoOPO4, TiOPO4, VOPO4, TaOPO4, or NbOPO4) forms a composite structure with the lithium-containing oxide, creating a material that maintains high voltage characteristics while improving initial efficiency and high-temperature stability through the protective and structurally stable phosphate layer.
2Use of energy by moving object
If high-voltage positive active materials are used to increase capacity, then energy density is improved, but side reactions with electrolyte increase causing self-discharge and capacity reduction
Solution Approach 1:
The phosphate compound acts as an intermediary layer between the lithium-containing oxide and the electrolyte. This intermediate coating prevents direct contact and harmful side reactions between the high-voltage positive active material and the electrolyte, thereby reducing self-discharge during storage and maintaining charging/discharging capacity while preserving the high capacity characteristics of the high-voltage material.
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 enhances the initial efficiency and high-temperature stability of lithium batteries, maintaining high capacity and extending their lifespan by minimizing side reactions with the electrolyte.
Implementation Method 1
improves initial efficiency and high-temperature stability by forming strong covalent bonds and reducing irreversible lithium ion intercalation
Implementation Method 2
a lithium-intercalatable phosphate compound disposed on the lithium-containing oxide
Implementation Method 3
high-voltage positive active materials in contact with an electrolyte may lead to side reactions on the surface of the positive active material
Data Source
AI summary
A positive active material including: a lithium-containing oxide, and a lithium-intercalatable phosphate compound disposed on the lithium-containing oxide.