Li-Ion Cathode-Electrolyte Composition for High-Voltage Thermal Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries face challenges in maintaining thermal stability and cycling stability as the operating voltage increases, particularly due to the dissolution of positive electrode materials and the deterioration of negative electrodes with metal doping elements.
Innovation Solution
Incorporating a boron-containing lithium salt, such as lithium bis(oxalato)borate, into the electrolyte, and adjusting the mass percentages of manganese and cobalt in the positive electrode active material, along with specific electrolyte additives, to form a stable passivation film and enhance thermal and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
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 electrolyte by introducing a boron-containing lithium salt (such as LiBOB) at specific concentrations (0.05-5% by mass). This parameter change modifies the electrolyte's properties to improve thermal stability while maintaining high-voltage operation capability, allowing the battery to operate at elevated cutoff voltages without sacrificing thermal safety.
Solution Approach 2:
The boron-containing lithium salt acts as an intermediary substance that mediates between the electrode materials and the bulk electrolyte. It forms protective interface films that prevent direct harmful interactions, thereby enhancing thermal stability. The intermediary forms a protective layer on electrode surfaces that prevents thermal runaway while allowing ionic transport.
2Reliability
If metal elements such as Mn are doped into the positive electrode material to improve thermal stability, then the thermal stability is improved, but the dissolution of the positive electrode material increases, threatening the thermal stability of the negative electrode
Solution Approach 1:
The boron-containing lithium salt serves as an intermediary that suppresses the dissolution of manganese ions from the doped cathode material. It forms a protective interface layer that prevents Mn ions from leaching into the electrolyte and migrating to the negative electrode, thereby maintaining the integrity of both electrodes while preserving the thermal stability benefits of Mn doping.
Solution Approach 2:
The patent converts the potentially harmful effect of Mn dissolution into a beneficial outcome by using the boron-containing salt to control and direct the dissolution process. The controlled interface reactions form protective films that actually enhance overall battery stability while allowing beneficial Mn doping for thermal stability.
3Reliability
If the concentration of boron-containing lithium salt in the electrolyte is increased to suppress dissolution and improve thermal stability, then the thermal stability is improved, but the cost and complexity of the electrolyte formulation increases
Solution Approach 1:
The patent optimizes the concentration parameter of the boron-containing lithium salt to a specific range (0.05-5% by mass, with preferred ranges of 0.1-2% or 0.5-1%). This parameter optimization achieves the desired thermal stability improvement while avoiding excessive concentration that would lead to increased cost and complexity. The optimized range balances performance benefits with formulation simplicity.
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 achieves improved thermal stability and cycling stability of both positive and negative electrodes, maintaining discharge capacity under high-temperature conditions and enhancing the battery's overall performance.
Implementation Method 1
introducing a boron-containing lithium salt into the electrolyte... it can form a stable and effective passivation film in a propylene carbonate (PC) solution
Implementation Method 2
the introduction of the boron-containing lithium salt, which suppresses the dissolution of manganese ions and improves the thermal stability
Implementation Method 3
maintains a discharge capacity without attenuation under high-temperature conditions
Data Source
AI summary
This application provides an electrochemical apparatus and an electronic apparatus. The electrochemical apparatus includes a positive electrode, the positive electrode includes a positive electrode active material, and the positive electrode active material contains metal elements Co and Mn, where based on a total mass of the positive electrode active material, a mass percentage of Mn is B%; and an electrolyte, the electrolyte includes a boron-containing lithium salt, where based on a total mass of the electrolyte, a mass percentage of the boron-containing lithium salt is C%; where 0.05 ≤ C ≤ 1, and 0.01 ≤ C/10B ≤ 2. The electrochemical apparatus of this application can achieve both high-temperature stability and cycling stability at high voltages, and has excellent hotbox performance.