Electrolyte Additive Pairing for High-Voltage Battery Interface Stability
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Solution Overview
Problem
The challenge of significant side reactions between the electrolyte solution and the electrode interface in lithium batteries at high voltages, leading to deterioration of high-temperature cycling and storage performance, is addressed by incorporating specific additives in the electrolyte solution to stabilize the interface.
Innovation Solution
A battery design incorporating a tricyanophosphite compound and an alkyl polycyanide compound in the electrolyte solution, with a specific mass ratio relative to the positive electrode areal density, forms a stable interface film to enhance the stability of the electrolyte and electrode interface, reducing electrolyte consumption and structural damage during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charging and discharging voltage of batteries is increased to boost platform voltage and enhance specific capacity of the positive electrode, then the energy density of the battery is improved, but the side reactions between the electrolyte solution and the positive and negative electrode interfaces are intensified, deteriorating the battery's cycling performance
Solution Approach 1:
The patent introduces a mediator substance (specific additive containing nitrogen-containing heterocyclic structure) into the electrolyte solution that acts as an intermediary between the electrode interface and the bulk electrolyte. This additive preferentially reacts with the electrode surface to form a stable protective film, mediating the interaction between high voltage and electrolyte, thereby reducing harmful side reactions while maintaining high operating voltage for high energy density
Solution Approach 2:
The patent changes the chemical composition parameter of the electrolyte solution by incorporating specific additives (0.1-5% by mass) with nitrogen-containing heterocyclic structures. This parameter change modifies the electrochemical properties of the electrolyte, enabling it to form more stable interface films at high voltages, thus improving cycling performance without sacrificing energy density
2Reliability
If additives are added to the electrolyte solution to stabilize the high-voltage cycling performance, then the cycling stability is improved, but the additives become increasingly difficult to play a sufficient role in stabilizing the high-temperature and high-pressure performance as the battery voltage further increases
Solution Approach 1:
The patent employs a composite electrolyte system combining multiple components: lithium salt, cyclic carbonate, chain carbonate, and specifically nitrogen-containing heterocyclic additive. This composite formulation creates synergistic effects where the additive works together with the solvent system to form a robust protective interface film that maintains stability under both high voltage and high-temperature conditions, addressing the limitation of single-component additives
3Quantity of substance
If the battery operates at high voltage to increase energy density, then the platform voltage and specific capacity are enhanced, but the interface stability between electrolyte solution and electrode deteriorates
Solution Approach 1:
The nitrogen-containing heterocyclic additive performs preliminary action by preferentially reacting with the electrode surface during initial cycles to form a stable protective film before the bulk electrolyte can cause harmful side reactions. This pre-formed interface layer acts as a barrier that maintains interface stability during high-voltage operation, enabling sustained high specific capacity without degradation
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 exhibits improved high-temperature cycling performance and storage performance at high voltages, with a cycle capacity retention rate of 80% at 45°C for up to 562 cycles and a thickness expansion rate of 5.9% at 60°C storage.
Implementation Method 1
The additives of the electrolyte solution include tricyanophosphite compounds and alkyl polycyanide compounds. Through the synergistic effect between the areal density of the positive electrode and the additives of the electrolyte solution, a very stable interface film and interface coordination effect can be achieved at the positive electrode
Implementation Method 2
an increase in battery voltage will intensify the side reactions between the electrolyte solution and the positive and negative electrode interfaces, thereby deteriorating the battery's cycling performance
Data Source
AI summary
A battery includes a positive and a negative electrode plate, a separator, and an electrolyte solution. The additives of the electrolyte solution include tricyanophosphite compounds and alkyl polycyanide compounds. It can solve problems of large side reactions between electrolyte solution and electrode interface, and the significant deterioration of high-temperature cycling performance and high-temperature storage performance of the battery under high voltage. By adding an appropriate amount of electrolyte additive according to the areal density of the positive electrode, it is possible to form a very stable interface film and interface coordination effect on the positive electrode, significantly improving the stability of the electrolyte solution and the positive electrode interface, reducing the consumption of the electrolyte solution and the damage to the positive electrode structure during battery cycling, and significantly enhancing the high-temperature cycling performance and high-temperature storage performance of the battery at high voltage.