Phosphate Coated Positive Electrode for High Voltage Battery Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in increasing capacity and energy density at high charge cut-off voltages, leading to degradation of positive electrode active materials and electrolytes, which affects storage and load characteristics, especially at high temperatures.
Innovation Solution
A non-aqueous electrolyte secondary battery with a positive electrode active material surface coated with a phosphate compound containing neodymium, samarium, europium, or other rare-earth elements, which reduces the reaction area and suppresses reactions with the electrolyte, improving high-temperature storage characteristics without degrading load characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charge cut-off voltage is increased to increase capacity and energy density, then the battery capacity and energy density are improved, but the positive electrode active material is degraded and the electrolyte is decomposed by oxidation, degrading battery characteristics
Solution Approach 1:
A phosphate compound coating layer is introduced as an intermediary between the positive electrode active material and the electrolyte. This coating layer suppresses the direct oxidation reaction between the electrolyte and the positive electrode active material, preventing electrolyte decomposition and positive electrode degradation even at high charge cut-off voltages (4.3V or higher), thereby enabling high capacity and energy density while maintaining battery reliability
Solution Approach 2:
The positive electrode active material is combined with a phosphate compound coating layer to form a composite structure. The coating layer contains phosphate compounds such as aluminum phosphate, gallium phosphate, or indium phosphate, which provide protective functionality while the core positive electrode material (e.g., lithium cobalt oxide, lithium nickel cobalt manganese oxide) provides high capacity, achieving both high energy density and improved stability
2Quantity of substance
If the charge cut-off voltage is increased to achieve high capacity, then the battery capacity is improved, but the positive electrode active material structure becomes unstable, significantly reducing battery capacity during high-temperature storage
Solution Approach 1:
The phosphate compound coating acts as a protective intermediary that stabilizes the positive electrode active material structure during high-temperature storage. The coating layer prevents structural degradation of the positive electrode material even when charged to high voltages (4.3V or higher), maintaining both high capacity and structural stability during storage at temperatures of 60°C or higher
Solution Approach 2:
The invention changes the chemical composition parameters of the positive electrode surface by applying a phosphate compound coating. This modification alters the surface properties to enhance thermal and structural stability, allowing the battery to maintain high capacity (80% or more of initial capacity) after storage at high temperatures, whereas uncoated materials would suffer significant capacity loss
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 battery achieves marked improvement in storage characteristics at high temperatures and maintains load characteristics by using a phosphate compound coating that specifically exhibits an anticatalyst effect, reducing the reaction area between the positive electrode active material and the electrolyte.
Implementation Method 1
at least part of a surface of the positive electrode active material is coated with a surface treatment layer composed of a phosphate compound
Implementation Method 2
the phosphate compound specifically exhibits an anticatalyst effect, reducing the reaction area between the positive electrode active material and the electrolyte
Data Source
AI summary
A positive electrode active material with least part of a surface coated with a surface treatment layer composed of a phosphate compound. The phosphate compound contains at least one element selected from the group consisting of neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.