Lithium Metal Battery Anode Layer for Uniform Deposition
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Solution Overview
Problem
Secondary batteries with metallic lithium negative electrodes face challenges in coulombic efficiency due to uneven deposition and dissolution of metallic lithium, leading to increased resistance and deteriorated cycle characteristics.
Innovation Solution
The secondary battery design incorporates a negative electrode active material layer comprising a first substance, such as an alloy or compound of Li and element X, and a second substance, such as a simple metal element M or its alloy/compound, with specific formation energy relationships to facilitate uniform lithium deposition and suppress void formation, along with a manufacturing method involving a laminated body with a compound of a metal element M and element X between the solid electrolyte and negative electrode current collector, promoting a conversion reaction during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic lithium is used as the negative electrode active material, then the battery capacity is improved, but the coulombic efficiency deteriorates due to uneven deposition and dissolution
Solution Approach 1:
The patent introduces a compound layer comprising a metal element M and element X as an intermediary between the solid electrolyte and metallic lithium. This compound layer mediates the deposition and dissolution processes, ensuring uniform lithium ion distribution and preventing direct contact between metallic lithium and the solid electrolyte, thereby improving coulombic efficiency while maintaining high battery capacity
Solution Approach 2:
The patent utilizes formation energy differences as a key parameter to control the chemical reactions. By selecting materials where the formation energy of LiX is lower than that of MX, the system enables spontaneous conversion reactions that uniformly distribute lithium ions during charging, addressing the uneven deposition problem while preserving high capacity
2Use of energy by moving object
If metallic lithium is deposited in the negative electrode, then the energy density is improved, but internal resistance increases due to void formation
Solution Approach 1:
The compound layer of metal element M and element X serves as a mediator that prevents void formation during lithium deposition. This intermediate layer ensures continuous contact between the metallic lithium and the solid electrolyte throughout charging and discharging cycles, eliminating the harmful effect of voids that would otherwise increase internal resistance while maintaining high energy density
Solution Approach 2:
The patent performs a preliminary conversion reaction during the first charging cycle where the compound MX converts to LiX and metal M. This preliminary action creates a favorable interface structure before subsequent cycling, ensuring uniform lithium deposition and preventing void formation that would increase internal resistance, thereby preserving high energy density
3Manufacturing precision
If a compound of metal element M and element X is placed between solid electrolyte and negative electrode current collector, then uniform lithium deposition is achieved, but the device structure becomes more complex
Solution Approach 1:
The patent combines multiple functions into the single compound layer of metal element M and element X. This layer simultaneously serves as a reaction substrate for uniform lithium deposition, a barrier preventing direct contact between lithium and solid electrolyte, and a source of metal M that catalyzes the conversion reaction. By merging these functions into one layer, the patent achieves uniform lithium deposition without proportionally increasing device 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
This configuration enhances coulombic efficiency by ensuring uniform and efficient lithium deposition, reducing voids and internal resistance, and improving cycle characteristics of the secondary battery.
Implementation Method 1
a compound of a metal element M and an element X is present between the solid electrolyte layer and the negative electrode current collector; and a formation energy EMX of the compound of the metal element M and the element X is higher than a formation energy ELiX of a compound of Li and the element X
Implementation Method 2
a solid electrolyte layer
Data Source
AI summary
A secondary battery comprising a metallic lithium negative electrode and having a coulombic efficiency. The secondary battery of the present disclosure comprises a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein the negative electrode active material layer comprises a first substance and a second substance, wherein the first substance is at least one of an alloy of Li and an element X and a compound of Li and the element X; the second substance is at least one of a simple substance of a metal element M, an alloy of Li and the metal element M, and a compound of Li and the metal element M; and a formation energy ELiX of the first substance is lower than a formation energy EMX of the compound of the metal element M and the element X.