Electrolyte Solution for High-Voltage Secondary Battery
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Solution Overview
Problem
Lithium secondary batteries face issues with low cycle characteristics at high temperatures and insufficient rate characteristics, particularly when using electrolyte solutions with high potential positive electrode materials, leading to decomposition, increased electrode resistance, and gas generation.
Innovation Solution
A non-aqueous electrolyte solution comprising two or more open chain sulfone compounds and one or more carbonate ester compounds, which suppresses gas generation and improves cyclic characteristics by maintaining stability under high temperature and high voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high potential positive electrode materials (4.5V or higher) are used to increase energy density, then battery capacity and operating potential are improved, but electrolyte decomposition occurs leading to gas evolution and capacity drop in long-term cycles
Solution Approach 1:
The patent introduces a specific electrolyte composition as an intermediary between the high potential positive electrode and the battery system. The electrolyte contains cyclic carbonate (15-40 vol%), chain carbonate (40-70 vol%), and cyclic carboxylate (10-30 vol%), which together form a stable interface that mediates the interaction between the electrode and electrolyte, preventing decomposition while maintaining high capacity utilization.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating cyclic carboxylate compounds (such as γ-butyrolactone, γ-valerolactone, or δ-valerolactone) in specific concentrations (10-30 vol%). This parameter change in electrolyte composition raises the decomposition potential and stabilizes the electrolyte at high voltages, enabling the battery to operate at 4.5V or higher without severe decomposition.
2Device complexity
If high potential positive electrode materials are used to reduce battery module size and weight, then the number of battery packs in series is reduced, but electrolyte decomposition causes increased internal resistance and capacity drop
Solution Approach 1:
The optimized electrolyte composition acts as a protective intermediary layer between the high potential electrode and the bulk electrolyte. The cyclic carboxylate component specifically forms a stable solid electrolyte interface (SEI) that prevents direct contact and decomposition reactions, thereby maintaining low internal resistance over time while enabling the simplified battery module design.
3Ease of manufacture
If conventional electrolyte compositions are used with high potential positive electrodes, then battery design is simplified, but decomposition leads to gas evolution and capacity deterioration under high-temperature storage
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding cyclic carboxylate compounds (γ-butyrolactone, γ-valerolactone, or δ-valerolactone) in concentrations of 10-30 vol%. This compositional change increases the thermal stability and decomposition potential of the electrolyte, suppressing gas evolution and capacity deterioration even under high-temperature storage conditions, while maintaining ease of manufacturing through straightforward mixing of commercially available components.
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 enhances long-term cycle characteristics and reduces gas generation in lithium ion secondary batteries, especially when using positive electrode active materials with potentials of 4.5V or higher, thereby improving battery performance and capacity retention.
Implementation Method 1
a non-aqueous electrolyte solvent comprising two or more compounds selected from open chain sulfone compounds represented by the following formula (1), and one or more compounds selected from carbonate ester compounds represented by the following formula (2)
Data Source
AI summary
The present invention provides a lithium ion secondary battery having excellent high temperature cycle characteristics. The present invention relates to an electrolyte solution containing a non-aqueous electrolyte solvent containing two or more open chain sulfone compounds represented by a specific formula and one or more carbonate ester compounds represented by a specific formula; and to a secondary battery comprising these.