Electrolyte Additive Composition for High-Temperature Li-Ion Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges in high-temperature storage and cycle performance due to the limitations of existing electrolyte additives, which either improve high-temperature storage at the expense of low-temperature discharge and cycle performance or vice versa, necessitating the development of additives that enhance both aspects simultaneously.
Innovation Solution
The use of a specific electrolyte composition that includes a non-fluorinated lithium borate compound and additives such as vinylene carbonate, lithium difluorophosphate, and silicon-containing carbonate compounds, optimized in weight ratios and concentrations to improve both high-temperature storage and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolyte additives are used to improve high-temperature storage performance, then high-temperature storage performance is improved, but low-temperature discharge performance and cycle performance deteriorate severely
Solution Approach 1:
The patent employs a composite additive system comprising multiple components (additive A: cyclic carboxylate 0.1-5 wt%, additive B: vinylene carbonate 0.1-5 wt%, additive C: fluoroethylene carbonate 0.1-5 wt%, additive D: lithium salt 0.1-5 wt%) that work synergistically. This composite approach allows the formation of a balanced protective film on the positive electrode that provides both high-temperature stability and low-temperature performance, resolving the contradiction between temperature-specific performance requirements.
Solution Approach 2:
The patent optimizes specific parameter ranges for each additive component to achieve the desired balance. By controlling the weight percentages of each additive within specific ranges and adjusting their ratios, the electrolyte forms a protective film with optimized impedance characteristics that performs well across both high and low temperature conditions, as well as during cycling.
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 electrolyte composition significantly enhances the cycle performance, high-temperature storage performance, and low-temperature impedance of lithium-ion batteries, as demonstrated by improved discharge capacity retention and reduced thickness swelling rates, thereby addressing the limitations of existing additives.
Implementation Method 1
most additives improve high-temperature storage performance by forming a film on a positive electrode
Implementation Method 2
electrochemical apparatuses (for example, lithium-ion batteries) are widely used in fields such as electric vehicles
Data Source
AI summary
An electrolyte, including an additive A, wherein the additive A comprises a non-fluorinated lithium borate compound; and at least one additive selected from an additive B, an additive C, an additive D, or an additive E, wherein the additive B comprises at least one of vinylene carbonate, fluoroethylene carbonate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate, or lithium difluorophosphate; the additive C comprises a compound comprising S═O; the additive D comprises a compound having 2 to 4 cyano groups; and the additive E comprises a silicon-containing carbonate compound. This application provides an electrolyte and an electrochemical apparatus. The electrolyte includes additives such as a non-fluorinated lithium borate compound, thereby effectively improving high-temperature storage performance, cycle performance, floating charge performance and/or overcharge performance of the electrochemical apparatus.