Anode Fluoride Coating for Lithium Metal Battery Cycle Stability
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Solution Overview
Problem
Lithium ion batteries face limitations in capacity increase, and existing lithium secondary batteries experience reduced cycle characteristics due to overvoltage and reductive decomposition of non-aqueous solvents during lithium metal deposition and dissolution.
Innovation Solution
A secondary battery design featuring an anode current collector coated with an alkaline earth metal fluoride coating layer, which reduces overvoltage and suppresses reductive decomposition, improving cycle characteristics by maintaining lithium metal deposition and dissolution efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is deposited on the anode during charge to achieve high capacity, then the battery capacity increases, but overvoltage occurs and reductive decomposition of non-aqueous solvent happens, worsening cycle characteristics
Solution Approach 1:
An alkaline earth metal fluoride coating layer is introduced as an intermediary between the anode current collector and the non-aqueous electrolyte. This coating layer mediates the interaction during lithium metal deposition and dissolution, reducing overvoltage and suppressing reductive decomposition of the electrolyte, thereby improving cycle characteristics while maintaining high capacity
Solution Approach 2:
The surface properties of the anode are modified by coating with alkaline earth metal fluoride, changing the electrochemical parameters at the electrode-electrolyte interface. This parameter change reduces overvoltage during lithium deposition and prevents solvent decomposition, resolving the contradiction between capacity and cycle life
2Device complexity
If the anode surface is left uncoated to maintain simplicity, then device complexity is low, but overvoltage increases and reductive decomposition occurs, worsening cycle characteristics
Solution Approach 1:
A thin coating layer of alkaline earth metal fluoride is applied to the anode current collector surface. This thin film provides protective and functional properties by reducing overvoltage and suppressing electrolyte decomposition, significantly improving cycle characteristics while adding minimal structural complexity
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 alkaline earth metal fluoride coating enhances discharge capacity retention and cycle stability by minimizing side reactions between lithium metal and non-aqueous solvents, leading to improved performance and longevity of the battery.
Implementation Method 1
the coating layer contains an alkaline earth metal fluoride; during charge, a lithium metal is deposited on the anode
Implementation Method 2
suppresses reductive decomposition of non-aqueous solvents during lithium metal deposition and dissolution
Implementation Method 3
during discharge, the lithium metal is dissolved in the non-aqueous electrolyte
Data Source
AI summary
Provided is a secondary battery comprising a cathode comprising a cathode current collector and a cathode mixture layer containing and a cathode active material, an anode comprising an anode current collector and coating layer, and a non-aqueous electrolyte containing a non-aqueous solvent and a lithium salt which has been dissolved in the non-aqueous solvent. A surface of the anode current collector is coated with the coating layer. The coating layer contains an alkaline earth metal fluoride. During charge, a lithium metal is deposited on the anode. During discharge, the lithium metal is dissolved in the non-aqueous electrolyte.