Multi-nitrile Electrolyte Additive for High-Voltage Lithium-Ion Batteries
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Solution Overview
Problem
High-voltage lithium-ion batteries face issues with oxidative activity and stability due to electrochemical oxidation and decomposition of non-aqueous electrolytes on the positive electrode, leading to decreased cycle life, low-temperature discharge characteristics, and high-temperature storage performance.
Innovation Solution
An electrolyte additive comprising a multi-nitrile compound and a sulfur-oxygen double bond-containing compound is used to form a stable solid electrolyte interface film on the negative electrode, improving the stability of the positive electrode and reducing interface resistance, thereby enhancing the cycle and storage performance of lithium-ion batteries at high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a film-forming additive is added to the electrolyte to protect the positive electrode at high voltage, then the stability of the positive electrode is improved, but the interface resistance increases and the C-rate performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte additive, using a specific multi-nitrile compound with controlled carbon chain length (C3-C10) and nitrile group arrangement. This parameter optimization allows the additive to form protective films with lower resistance compared to conventional additives, thus improving C-rate performance while maintaining electrode stability.
Solution Approach 2:
The patent employs a composite additive system combining multi-nitrile compounds with other electrolyte components. This composite approach creates a synergistic effect where the multi-nitrile compound forms a stable yet conductive interface film that balances protection and ion transport, resolving the contradiction between stability and productivity.
2Quantity of substance
If the working voltage is increased above 4.35 V to improve energy density, then the battery capacity is improved, but the oxidative activity increases and the electrolyte decomposes producing gases
Solution Approach 1:
The multi-nitrile compound additive performs preliminary protective action by forming a stable interface film on the positive electrode before electrolyte decomposition can occur. This pre-formed protective layer prevents oxidative degradation and gas generation, enabling safe operation at high voltages above 4.35 V while maintaining improved battery capacity.
3Stability of the object's composition
If conventional additives are used to form protective films, then electrode stability is improved, but the discharge rate decreases and capacity is reduced
Solution Approach 1:
The patent optimizes the molecular structure parameters of the additive by using multi-nitrile compounds with specific carbon chain lengths (C3-C10) and controlled numbers of nitrile groups (2-4 groups). This parameter optimization creates interface films with enhanced ion conductivity, allowing high discharge rates while maintaining electrode stability, unlike conventional additives that form overly resistive films.
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 additive improves the stability and performance of lithium-ion batteries by forming a uniform film on the negative electrode, reducing resistance and enhancing cycle and storage performance, allowing the batteries to maintain capacity and function effectively at high temperatures and high voltages.
Implementation Method 1
Increased oxidative activity and decreased stability may cause a non-aqueous electrolyte to undergo electrochemical oxidation on the positive electrode surface and then to decompose to produce gases
Implementation Method 2
transition metal elements (e.g. nickel, cobalt, manganese, etc.) in the materials forming the positive electrode (cathode) may undergo reduction reaction and dissolve out
Implementation Method 3
Such an additive can form a film on the positive electrode
Implementation Method 4
The electrolyte additive may comprise a multi-nitrile compound and a sulfur-oxygen double bond-containing compound
Data Source
AI summary
The present disclosure discloses an electrolyte additive and its use in a lithium-ion battery. The lithium-ion battery may include an electrolyte solution. The electrolyte solution may include an organic solvent, a lithium salt, and an electrolyte additive. The electrolyte additive may comprise a multi-nitrile compound and a sulfur-oxygen double bond-containing compound. The use of the electrolyte additive in a lithium-ion battery enables the lithium-ion battery to maintain a good cycle life, low-temperature discharge characteristics, and high-temperature storage characteristics even at a high voltage.