Non-Aqueous Electrolyte Composition for Dendrite-Resistant Lithium Batteries
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Solution Overview
Problem
Lithium metal secondary batteries face issues with rapid capacity fading and safety hazards due to side reactions and dendritic lithium growth, leading to 'range anxiety' and poor cycle performance.
Innovation Solution
A non-aqueous electrolyte comprising orthocarbonate, chain carbonate, and lithium salt, with specific mass ratios and fluorinated components, which promotes the formation of a highly inorganic Solid Electrolyte Interphase (SEI) film, inhibiting dendrite growth and enhancing cycle life and safety by reducing viscosity and improving ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as the negative electrode to increase energy density, then the energy density is improved, but dendritic lithium growth and capacity fading occur
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing orthocarbonate with specific molecular structures (R1-R9 groups) and controlling its content (10-80 mass%), which fundamentally alters the SEI film formation mechanism and transforms lithium deposition morphology from dendrites to masses
Solution Approach 2:
The patent creates a composite electrolyte system combining orthocarbonate (as main solvent), chain carbonate, and cyclic carbonate, where each component plays a synergistic role: orthocarbonate forms inorganic SEI films, chain carbonate reduces viscosity, and cyclic carbonate enhances ion conductivity, collectively solving the dendrite problem while maintaining high energy density
2Reliability
If conventional electrolytes are used, then ion conductivity is maintained, but SEI film formation leads to dead lithium and capacity fading
Solution Approach 1:
The patent converts the harmful side reaction between lithium metal and electrolyte into a beneficial process by designing orthocarbonate that preferentially decomposes to form stable inorganic SEI films and LiF layers, which protect the lithium metal surface and prevent further harmful reactions, thus transforming capacity fading into a protective mechanism
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing orthocarbonate with specific molecular structures (R1-R9 groups) and controlling its content (10-80 mass%), which fundamentally alters the SEI film formation mechanism and transforms lithium deposition morphology from dendrites to masses
3Reliability
If orthocarbonate content is increased to improve SEI film formation, then cycle performance is improved, but electrolyte viscosity increases
Solution Approach 1:
The patent optimizes the concentration parameter of orthocarbonate within the specific range of 10-80 mass%, and adjusts the molecular structure parameters (R1-R9 groups) to balance SEI film formation capability with viscosity control, ensuring both cycle performance and ion transport efficiency
Solution Approach 2:
The patent creates a composite electrolyte system where orthocarbonate (10-80 mass%) provides inorganic SEI film formation, chain carbonate reduces viscosity through its linear molecular structure, and cyclic carbonate enhances ion conductivity, with each component compensating for the others' limitations
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 electrolyte composition significantly improves the cycle life and safety of lithium metal secondary batteries by transforming lithium metal deposition from dendrites to masses, reducing corrosion, and forming a protective passivation layer, thereby enhancing thermal safety and ion transport efficiency.
Implementation Method 1
SEI film formation dominated by anion decomposition is promoted. Highly inorganic SEI film components formed by anion decomposition may promote lithium metal deposition to transform from dendrites to masses
Implementation Method 2
The chain carbonate mainly plays a role of reducing the viscosity of the electrolyte, and improving the wettability and the ion conductivity
Implementation Method 3
The fluorinated chain carbonate or fluorinated cyclic carbonate may decompose on a surface of the lithium metal negative electrode to form lithium fluoride and other inorganic components
Implementation Method 4
the non-aqueous electrolyte using the orthocarbonate as one of major solvents may react with the lithium metal at 80° C. and produce a protective layer capable of effectively passivating the surface of the lithium metal
Data Source
AI summary
Provided are a non-aqueous electrolyte, a secondary battery, a battery module, a battery pack, and an electrical device. The non-aqueous electrolyte includes orthocarbonate, chain carbonate, cyclic carbonate, and lithium salt, a mass content of the orthocarbonate is 10% to 80%, and at least one of the chain carbonate or the cyclic carbonate is fluoride. A central carbon atom of the orthocarbonate is bonded to four oxygen atoms, each of which is further bonded to an alkyl or halogenated alkyl chain, which plays an electron attraction role for lone pair electrons of the oxygen atoms, and increases steric hindrance surrounding the oxygen atoms, weakening the capability of the oxygen atoms in binding to lithium ions, and facilitating SEI film formation dominated by anion decomposition.