Lithium Fluoride Hydroxide Anode Coating for Battery Cycle Stability
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Solution Overview
Problem
Secondary batteries using lithium metal anodes suffer from dendrite crystal precipitation, leading to high current density, electrolyte decomposition, and internal short circuits, which degrade cycle characteristics and energy density.
Innovation Solution
A battery design with an anode coating having a peak intensity ratio of Li2F+ to Li2OH+ of 1 or more, obtained through positive ion analysis by Time of Flight-Secondary Ion Mass Spectrometry, is implemented to inhibit electrolyte decomposition and improve cycle characteristics, particularly when using anode active materials capable of inserting and extracting lithium, such as silicon or tin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as anode active material, then high energy density and high output are achieved, but dendrite crystal precipitates causing electrolyte decomposition and poor cycle characteristics
Solution Approach 1:
A coating layer containing lithium fluoride and lithium hydroxide is introduced as an intermediary between the lithium metal anode and the electrolyte. This coating layer prevents direct contact and harmful reactions between the lithium metal and electrolyte, thereby improving cycle characteristics while maintaining high energy density
Solution Approach 2:
The anode is constructed as a composite structure combining lithium metal with a coating layer of lithium fluoride and lithium hydroxide. This composite material approach allows the lithium metal to provide high energy density while the coating layer provides stability and prevents dendrite formation, resolving the contradiction between energy density and cycle characteristics
2Quantity of substance
If silicon or tin is used as anode active material, then high capacity is achieved, but cycle characteristics are lower than carbon materials
Solution Approach 1:
The coating layer acts as a protective intermediary that stabilizes the interface between silicon/tin anode materials and the electrolyte, preventing harmful side reactions and maintaining structural integrity during cycling, thereby improving cycle characteristics while preserving high capacity
Solution Approach 2:
The coating layer modifies the surface properties and chemical composition of the anode interface, changing parameters such as surface stability and electrochemical behavior to improve cycle characteristics while maintaining the high capacity benefits of silicon or tin materials
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 anode coating effectively inhibits oxidation and side reactions, enhancing battery cycle characteristics and energy density by preventing dendrite formation and electrolyte decomposition, thereby improving the overall performance of lithium-ion batteries.
Implementation Method 1
the coating effectively inhibits oxidation and side reactions
Implementation Method 2
decomposition reaction of the electrolyte can be inhibited
Data Source
AI summary
A battery capable of improving battery characteristics such as cycle characteristics is provided. A coating containing lithium fluoride and lithium hydroxide is provided on the surface of an anode active material layer. The ratio between lithium fluoride and lithium hydroxide is in the range, in which the Li2F+/Li2OH+ peak intensity ratio obtained in positive ion analysis by a Time of Flight-Secondary Ion Mass Spectrometry is 1 or more. The anode active material layer contains a substance containing Si or Sn as an element as an anode active material. By the coating, oxidation of the anode active material layer is inhibited, and decomposition reaction of the electrolytic solution is inhibited.