Secondary Battery Inorganic Solid Layer Electrolyte
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving both high-temperature durability and low-temperature performance due to the reactivity of nonaqueous electrolytes with positive electrodes, leading to reduced ion conductivity and cycle life.
Innovation Solution
Incorporating an inorganic solid-containing layer with a mixed solvent of fluorinated carbonate and fluorinated ether, along with lithium salt and inorganic solid particles, between the positive and negative electrodes to enhance ion conductivity, oxidation resistance, and wettability, thereby improving cycle life and temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a nonaqueous electrolyte with high ion conductivity at low temperature is used, then low-temperature performance is improved, but the electrolyte reacts with the positive electrode at high temperature, causing lifetime performance to decrease
Solution Approach 1:
An inorganic solid-containing layer is introduced as an intermediary between the positive electrode and the electrolyte. This layer prevents direct contact and reaction between the electrolyte and positive electrode at high temperatures, while still allowing lithium ion transport. The inorganic solid particles form a protective barrier that mediates the interaction, solving the contradiction between low-temperature conductivity and high-temperature stability.
Solution Approach 2:
The electrolyte system is transformed into a composite structure combining organic electrolyte with inorganic solid particles. This composite electrolyte maintains the liquid electrolyte's ion conductivity while incorporating the inorganic solid's thermal stability and oxidation resistance. The composite structure enables both low-temperature performance and high-temperature durability.
2Power
If conventional electrolytes are used to achieve high output, then output performance is improved, but high-temperature durability and low-temperature performance cannot be achieved simultaneously
Solution Approach 1:
The chemical composition parameters of the electrolyte are optimized by selecting specific fluorinated carbonates and fluorinated ethers with appropriate molecular structures. These parameter changes confer both low-temperature fluidity (maintaining output performance) and high-temperature oxidation resistance (expanding temperature adaptability). The inorganic solid particles further modify the system parameters to enhance thermal stability.
3Speed
If the electrolyte reacts with the positive electrode at high temperature, then ion conductivity may increase, but oxidative decomposition occurs, reducing cycle life
Solution Approach 1:
The potential harmful reaction between electrolyte and positive electrode is converted into a beneficial process. The inorganic solid-containing layer facilitates controlled initial reactions that form stable surface films, preventing subsequent oxidative decomposition. This converts what would be a harmful continuous reaction into a beneficial one-time film-forming process, preserving cycle life while maintaining ion conductivity.
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 effectively suppresses oxidative decomposition, increases ion conductivity, and enhances low-temperature performance, allowing for the practical use of high-voltage batteries with improved safety and durability across a wide temperature range.
Implementation Method 1
the inorganic solid-containing layer contains a mixed solvent, a lithium salt dissolved in the mixed solvent, and inorganic solid particles
Implementation Method 2
enhance ion conductivity, oxidation resistance, and wettability, thereby improving cycle life and temperature performance
Implementation Method 3
enhance ion conductivity, oxidation resistance, and wettability
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
According to one approach, provided is a secondary battery (100) including a positive electrode (3), a negative electrode (4) capable of allowing lithium ions to be inserted and to be extracted, and an inorganic solid-containing layer (5). The inorganic solid-containing layer (5) is disposed between the positive electrode (3) and the negative electrode(4). The inorganic solid-containing layer (5) contains a mixed solvent, a lithium salt dissolved in the mixed solvent, and inorganic solid particles. The mixed solvent includes a fluorinated carbonate and a fluorinated ether.