Selenocyanate Electrolyte Additive for High-Voltage Battery CEI Stability
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Solution Overview
Problem
High-voltage lithium-ion batteries face challenges in achieving high energy density and commercial viability due to oxidative decomposition of electrolyte solutions at elevated voltages, leading to poor high-temperature and cycling performance.
Innovation Solution
An electrolyte solution comprising an organic solvent, an electrolyte salt, and a selenocyanate salt additive that forms a high-strength, inorganic-rich Chemical-Electrochemical Interface (CEI) film at the positive electrode, reducing oxidative decomposition and enhancing stability and high-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the voltage of lithium-ion battery is increased to 4.5 V or above to improve energy density, then the energy density is improved, but the electrolyte solution is easily oxidatively decomposed and the high-temperature cycling performance and high-temperature storage performance deteriorate
Solution Approach 1:
The patent introduces a selenocyanate salt as an intermediary substance that mediates between the high-voltage positive electrode and the electrolyte solution. This additive forms a protective interface film that prevents direct contact and oxidative decomposition reactions, enabling the battery to operate at 4.5V or above without suffering from electrolyte decomposition issues
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding selenocyanate salt at specific concentrations (0.01-5 wt%). This parameter change transforms the electrolyte's interfacial properties, forming a stable CEI film that enables high-voltage operation while maintaining thermal stability and preventing oxidative decomposition
2Reliability
If conventional electrolyte additives are used to protect against oxidative decomposition, then some protection is provided, but the protective film lacks sufficient strength and inorganic content to effectively reduce active material loss at high temperature
Solution Approach 1:
The patent changes the chemical composition parameters by introducing selenocyanate salt, which contains selenium atoms that form inorganic-rich protective films. This parameter change transforms the film's chemical composition, increasing its inorganic content and structural strength to effectively prevent active material loss at high temperatures
Solution Approach 2:
The patent creates a composite interface film structure by combining selenocyanate salt with existing electrolyte components. This composite film integrates the benefits of conventional additives with the unique properties of selenocyanate, resulting in a film with enhanced strength, inorganic content, and protective capabilities
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 significantly improves the battery's stability and high-temperature and high-pressure performance by reducing oxidative decomposition and active material loss, making high-voltage lithium-ion batteries more suitable for commercial applications.
Implementation Method 1
oxidatively decomposing an additive A (a selenocyanate salt) at a positive electrode to form a CEI film
Data Source
AI summary
Disclosed are an electrolyte solution and a battery including the electrolyte solution. The electrolyte solution includes an organic solvent, an electrolyte salt, and an additive A; and the additive A is a selenocyanate salt. In the present disclosure, the following effects are achieved by oxidatively decomposing an electrolyte additive at a positive electrode to form a CEI film that has a high strength and is rich in inorganic matter: oxidative decomposition side reactions of the electrolyte solution are greatly reduced; and a loss of a positive electrode active material at a high temperature and a high pressure is decreased. Therefore, performance of a battery at a high temperature and a high pressure is improved, and cycling stability and high-temperature stability of the battery are improved.