Aqueous Li-Ion Battery Electrolyte for High-Current Vehicle Cells
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high current discharge performance, cycle life, and safety due to low ion conductivity and high-temperature instability of nonaqueous electrolytes, making them unsuitable for vehicle applications, especially in high-temperature environments and cold climates.
Innovation Solution
A lithium ion secondary battery design incorporating a negative electrode with titanium-containing oxide and additive elements like zinc, alumina, and a specific electrolyte composition with lithium ions, anions, and an aqueous solvent, which enhances ion conductivity and suppresses hydrogen generation, thereby improving cycle life and discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If nonaqueous electrolyte is used to achieve high voltage and energy density, then energy density is improved, but ion conductivity is reduced and high-temperature stability deteriorates
Solution Approach 1:
The patent changes the fundamental parameter of the electrolyte from nonaqueous to aqueous-based, which fundamentally alters the chemical stability profile. Aqueous electrolytes inherently provide better high-temperature stability due to the strong O-H bonds in water molecules, preventing decomposition at elevated temperatures while maintaining acceptable ion conductivity through optimized lithium salt concentration and additives.
Solution Approach 2:
The patent employs composite electrolyte systems combining aqueous-based electrolytes with specific lithium salts and additives to achieve both high ion conductivity and stability. The composite approach integrates multiple components working synergistically: the aqueous solvent provides thermal stability, lithium salts provide ion conductivity, and additives enhance overall performance and safety.
2Power
If nonaqueous electrolyte is used to achieve high voltage operation, then voltage is improved, but ion conductivity is reduced leading to increased resistance
Solution Approach 1:
The patent optimizes the concentration of lithium salts in the aqueous electrolyte to achieve the desired balance between voltage and ion conductivity. By adjusting the lithium salt concentration and selecting appropriate lithium compounds, the system maintains high voltage operation while ensuring sufficient ion conductivity for practical applications.
3Power
If organic solvent is used in nonaqueous electrolyte to enable high voltage, then voltage range is improved, but heat stability deteriorates due to decomposition at high temperature
Solution Approach 1:
The patent fundamentally changes the solvent parameter from organic to aqueous-based. Water's high bond energy and thermal stability prevent decomposition at elevated temperatures, eliminating the heat stability issues inherent in organic solvents. The aqueous-based electrolyte maintains the required voltage range while providing superior thermal and chemical stability.
4Reliability
If solid electrolyte is used to improve safety, then safety is improved, but ion conductivity is further reduced making large current discharge difficult
Solution Approach 1:
The patent changes the electrolyte state parameter from solid to aqueous-based liquid or gel. This fundamental parameter change restores high ion conductivity while maintaining safety through the inherent stability of aqueous systems. The aqueous electrolyte enables both large current discharge and safe operation by combining liquid-phase ion transport with chemically stable 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 battery exhibits significantly improved cycle life, storage performance, and large current discharge capabilities, making it suitable for vehicle applications by increasing ion conductivity and reducing hydrogen generation, thus enhancing safety and efficiency.
Implementation Method 1
The electrolyte contains lithium ions, an anion and an aqueous solvent containing water... ion conductivity of the nonaqueous electrolytic solution is lower than that of the aqueous solution-based electrolytic solution
Implementation Method 2
a nonaqueous electrolyte battery charged and discharged by movement of Li ions between a negative electrode and a positive electrode
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to one embodiment, a secondary battery including a positive electrode, a negative electrode, and an electrolyte is provided. The negative electrode includes titanium-containing oxide and at least one kind of element selected from the group consisting of B, P, Al, La, Zr, Ge, Zn, Sn, Ga, Pb, In, Bi, and Tl. The electrolyte includes lithium ions and a solvent containing water.