Lithium Battery Electrolyte Additive for Uniform Anode Deposition
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high cycle-life characteristics due to the high reactivity of lithium metal, which leads to explosive reactions and uneven lithium ion deposition, causing capacity loss and safety issues.
Innovation Solution
Incorporating a smoothing additive with a reduction potential of −0.5 V to 0.9 V, such as butynediol or thiourea, in the electrolyte to uniformly distribute lithium ions on the negative electrode, preventing uneven deposition and enhancing cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is applied to the negative electrode to achieve high specific capacity, then the energy density is improved, but the reactivity with water and oxygen increases causing safety issues
Solution Approach 1:
A coating layer comprising a polymer and LiF is introduced as an intermediary between the lithium metal negative electrode and the external environment (water and oxygen). This coating layer acts as a protective barrier that prevents direct contact between the highly reactive lithium metal and harmful external substances, thereby maintaining safety while preserving the high energy density benefits of lithium metal.
2Quantity of substance
If lithium ions are deposited on the negative electrode during charging, then the battery capacity is improved, but uneven deposition occurs causing capacity loss and deteriorated cycle-life characteristics
Solution Approach 1:
The coating layer is designed with specific local properties (comprising polymer and LiF) that create uniform local conditions across the negative electrode surface. This localized modification of the surface properties ensures uniform lithium ion deposition throughout the electrode, preventing the formation of protrusions and ensuring consistent performance across all regions of the battery during cycling.
Solution Approach 2:
The coating layer is applied to the negative electrode before the charging process begins. This preliminary action prepares the surface in advance to receive lithium ions uniformly, preventing uneven deposition and protrusion formation from occurring in the first place, thereby maintaining reliable cycle-life characteristics.
3Reliability
If a coating layer comprising polymer and LiF is formed on the negative electrode, then the cycle-life characteristics are improved, but the device complexity increases
Solution Approach 1:
The coating layer is formed as a composite material comprising polymer and LiF components. This composite structure combines the beneficial properties of both materials to achieve improved cycle-life characteristics. The composite approach allows for enhanced performance while maintaining a relatively simple overall structure that can be integrated into existing battery designs.
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 use of the smoothing additive improves the cycle-life characteristics of lithium secondary batteries by preventing lithium dendrite growth and maintaining a stable structure during repeated charging and discharging, thus enhancing safety and capacity retention.
Implementation Method 1
is repeatedly adsorbed and desorbed to the surface of the negative electrode during charging and discharging
Implementation Method 2
lithium ions generated in the positive electrode are transferred to the negative electrode through the electrolyte
Implementation Method 3
it allows a slow reduction of the current collector due to the lithium ions during charging and discharging
Data Source
AI summary
The present invention relates to a rechargeable lithium battery, the battery comprising: a positive electrode; a negative electrode; and an electrolyte comprising a smoothing additive having a reduction potential of at least −0.5 V, but less than 0.9 V.