Li-Ion Battery Electrolyte Composition for High-Voltage Thermal Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high energy density while maintaining thermal stability and cycling stability due to the deterioration of positive and negative electrodes with increased voltage, particularly at high temperatures.
Innovation Solution
Incorporating manganese and cobalt elements into the positive electrode active material and a sulfonyl imide lithium salt into the electrolyte, with specific mass percentage ratios, to enhance structural stability and ionic conductivity, thereby improving thermal and high-temperature cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating cutoff voltage of a lithium-ion battery is increased to increase energy density, then the energy density is improved, but the thermal stability of the battery deteriorates sharply
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode material by doping manganese elements at controlled concentrations (0.01≤x≤0.10 in Li1-xMnxCO2) to modify the material's properties. This allows the battery to operate at high voltages (4.3V-4.4V) while maintaining thermal stability through the stabilizing effect of manganese doping on the crystal structure.
Solution Approach 2:
The patent creates a composite positive electrode material by doping manganese into the LiCoO2 crystal structure, forming Li1-xMnxCO2. This composite approach combines the high voltage characteristics of LiCoO2 with the thermal stability provided by manganese doping, resolving the contradiction between energy density and thermal stability.
2Reliability
If manganese elements are doped into the positive electrode material to improve high-temperature stability, then the structural stability is improved, but the thermal stability of the negative electrode deteriorates
Solution Approach 1:
The patent precisely controls the manganese doping concentration parameter (0.01≤x≤0.10) to optimize the balance between positive electrode stability and negative electrode protection. This parameter optimization prevents excessive manganese dissolution that would harm the negative electrode while maintaining enough doping to stabilize the positive electrode structure.
Solution Approach 2:
The patent introduces an intermediary protective coating on the negative electrode to prevent direct contact between dissolved manganese ions from the positive electrode and the negative electrode material. This intermediary layer allows beneficial manganese doping effects on the positive electrode while blocking harmful effects on the negative electrode.
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 proposed solution achieves balanced thermal stability of both electrodes, enhancing the battery's high-temperature cycling stability and safety performance.
Implementation Method 1
the introduction of the lithium salt, which suppresses the dissolution of manganese ions and improves the thermal stability and ionic conductivity of the electrolyte
Implementation Method 2
the introduction of the lithium salt, which suppresses the dissolution of manganese ions and improves the thermal stability and ionic conductivity of the electrolyte
Implementation Method 3
Mn is stable to O, which improves the structural stability of the positive electrode material
Data Source
AI summary
An electrochemical apparatus includes a positive electrode, a negative electrode, and an electrolyte, where the positive electrode includes a positive electrode active material, the positive electrode active material contains a manganese element and a cobalt element, and based on a total mass of the positive electrode active material, a mass percentage of the manganese element is B %; the electrolyte includes a sulfonyl imide lithium salt, and based on a total mass of the electrolyte, a mass percentage of the sulfonyl imide lithium salt is C %; where 0.1≤C≤15 and 0.02≤C/10B≤30.