High-Temperature Li-Ion Electrolyte Water Removal Additive
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Solution Overview
Problem
Lithium-ion batteries experience significant performance deterioration at high temperatures due to electrolyte auto-catalysis, leading to HF generation, which causes side reactions that reduce battery capacity, increase internal resistance, and shorten cycle life, with existing methods failing to adequately address the stability of the electrode-electrolyte interface and HF-induced degradation.
Innovation Solution
A high-temperature lithium-ion battery electrolyte comprising a lithium salt, organic solvent, and a water removal additive, specifically a cyclic anhydride compound, which eliminates trace water and restrains HF generation, combined with film-forming additives to protect the electrochemical system and improve high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a lithium-ion battery operates at high temperature (>60°C), then the battery can function in harsh environments, but the electrolyte auto-catalyzes to generate H2O which converts to HF, causing severe performance deterioration including capacity decay, increased internal resistance, and shortened cycle life
Solution Approach 1:
The patent applies preliminary action by adding a water removal additive (cyclic carboxylate compound) to the electrolyte before battery operation. This additive proactively removes trace water from the system, preventing the subsequent auto-catalytic generation of HF that would otherwise occur during high-temperature operation. The water removal mechanism is activated in advance to eliminate the root cause of performance deterioration.
Solution Approach 2:
The patent uses a cyclic carboxylate compound as an intermediary substance between the electrolyte components and water molecules. This intermediary additive specifically binds to and removes trace water through complexation, preventing water from participating in the auto-catalytic reaction that generates HF. The intermediary substance protects the electrode-electrolyte interface from HF-induced damage.
2Reliability
If existing methods add negative electrode film-forming additives to improve high-temperature performance, then some protection is achieved, but the method does not address electrolyte auto-catalysis and HF generation that destroys the positive electrode interface
Solution Approach 1:
The patent applies the taking out principle by extracting and removing the harmful element (trace water) from the electrolyte system using a water removal additive. Instead of adding multiple complex additives to counteract HF effects, the solution extracts the root cause (water) that triggers the auto-catalytic HF generation, thereby simplifying the overall approach while effectively improving high-temperature performance.
Solution Approach 2:
The patent changes the chemical parameter of the electrolyte by introducing a cyclic carboxylate compound with specific water-binding properties. This parameter change (adding water-removing capability) fundamentally alters the electrolyte's behavior at high temperatures, preventing the auto-catalytic reaction without requiring complex multi-component formulations.
3Object-generated harmful factors
If trace water is present in the electrolyte, then HF is generated through auto-catalysis at high temperature, but eliminating water completely is difficult due to residual trace water from production processes
Solution Approach 1:
The patent applies self-service by enabling the electrolyte system to automatically remove its own trace water contamination through the water removal additive. The cyclic carboxylate compound continuously binds to and removes water molecules that enter the system during production or operation, making the electrolyte self-cleaning and eliminating the need for extremely precise manufacturing controls.
Solution Approach 2:
The cyclic carboxylate compound serves as an intermediary that facilitates water removal from the electrolyte system. This intermediary substance provides a practical solution to the manufacturing precision challenge by chemically binding to trace water, effectively eliminating HF generation pathways without requiring ultra-dry production conditions.
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 effectively enhances high-temperature storage and cycling performance by preventing HF-induced side reactions, maintaining over 87% capacity recovery after 90 days at 60°C and retaining capacity above 87% after 500 weeks of cycling, significantly improving battery reliability in harsh environments.
Implementation Method 1
the water removal additive is capable of eliminating residual trace water introduced in a battery production process and trace water generated in a subsequent high-temperature process
Implementation Method 2
adding a negative electrode film-forming additive to the electrolyte to effectively form a film on the surface of the negative electrode
Data Source
AI summary
The present invention provides a high-temperature lithium-ion battery electrolyte, including a lithium salt, an organic solvent, and a water removal additive. A structural formula of the water removal additive is shown as a formula (1): formula (1), where R1 is a -NCH-(CH2)n-CN group, and 0<n≤20; R2 is a -R11-CO-NR12R13 group, R11 is a -(CH2)m- group, 0≤m<19, each of R12 and R13 is one independently selected from H and -(CH2)x-CH3 groups, 0≤x≤19-m, and both m and x are integers; and R3 is any one selected from H, F, Cl, and Br. The high-temperature lithium-ion battery electrolyte can effectively eliminate trace water in a battery system, restrain HF generation, protect an electrochemical system in a battery, and significantly improve high-temperature storage performance and high-temperature cycling performance of a lithium-ion battery. The present invention further provides a production method for the electrolyte and a high-temperature lithium-ion battery that includes the electrolyte.