Nonaqueous Electrolyte Composition for High-Ni Battery Heat Stability
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in achieving high capacity retention, low gas generation, and enhanced safety, particularly at high temperatures, with existing technologies failing to provide optimal performance across these criteria simultaneously.
Innovation Solution
A nonaqueous electrolyte secondary battery design incorporating a positive electrode with a lithium transition metal compound comprising Ni, Mn, and Co, and a nonaqueous electrolyte solution containing monofluorophosphate and/or difluorophosphate, optimized with specific molar ratios and additives to enhance high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium-containing transition metal oxide is used as a positive electrode with high Ni content to achieve high capacity, then the battery capacity is improved, but the high temperature stability and safety deteriorate due to increased metal dissolution and heat generation
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core contains high-Ni lithium transition metal oxide for high capacity, while the shell contains protective coating layers (such as aluminum oxide, aluminum hydroxide, or fluorinated compounds) that provide high-temperature stability. This spatial differentiation allows each region to perform its specialized function: the core delivers capacity while the shell provides protection against metal dissolution and heat generation at elevated temperatures.
Solution Approach 2:
The patent employs composite materials by combining lithium transition metal oxide with protective coating materials to form a composite positive electrode structure. The composite consists of the active lithium-containing transition metal oxide particles (with specific compositions like LiNi0.8Co0.1Mn0.1O2) integrated with protective layers that reduce metal dissolution and suppress exothermic reactions, thereby achieving both high capacity and high temperature stability simultaneously.
2Use of energy by moving object
If the battery is designed for high energy density to improve performance, then the energy storage capacity is enhanced, but the high temperature safety deteriorates due to increased heat generation
Solution Approach 1:
The patent converts the harmful heat generation issue into a benefit by incorporating thermally stable protective coatings that actually utilize the thermal energy. The protective layers (such as fluorinated compounds or metal hydroxides) have high thermal stability and can withstand high temperatures without decomposing, effectively dissipating heat and preventing thermal runaway. This transforms the heat generation problem into an opportunity to demonstrate the effectiveness of the protective coating design.
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 high capacity retention, reduced gas generation, and improved safety at elevated temperatures, ensuring low resistance and minimal metal dissolution and heat generation.
Implementation Method 1
a nonaqueous electrolyte solution containing a monofluorophosphate and/or a difluorophosphate
Implementation Method 2
a positive electrode with a positive electrode active material capable of absorbing and releasing a metal ion; a negative electrode with a negative electrode active material capable of absorbing and releasing a metal ion
Implementation Method 3
the amount of heat generation at a high temperature is small
Data Source
AI summary
Provided is a nonaqueous electrolyte secondary battery, including a positive electrode with a positive electrode active material capable of absorbing and releasing a metal ion; a negative electrode with a negative electrode active material capable of absorbing and releasing a metal ion; and a nonaqueous electrolyte solution; wherein the positive electrode active material includes a lithium transition metal compound, and the positive electrode active material includes at least Ni, Mn and Co, wherein the molar ratio of Mn/(Ni+Mn+Co) is larger than 0 and not larger than 0.28, the molar ratio of Ni/(Ni+Mn+Co) is 0.45 or more, the plate density of the positive electrode is 3.3 g/cm3 or more; and the nonaqueous electrolyte solution includes a monofluorophosphate and/or a difluorophosphate. A total content of the monofluorophosphate and/or difluorophosphate is 0.01% by mass or more in terms of the concentration in the nonaqueous electrolyte solution.