Lithium Metal Composite Anode Layer for Press-Stable Solid-State Batteries
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Solution Overview
Problem
Lithium secondary batteries face stability issues due to the liquefaction of lithium metal under high-temperature and high-pressure conditions, leading to deformation and short-circuits in all-solid secondary batteries, which affects their performance and lifespan.
Innovation Solution
A negative electrode layer comprising a lithium metal composite (LMC) with high elasticity and hardness is introduced, along with a carbon layer to prevent liquefaction and enhance electrochemical stability, allowing for uniform lithium nucleation and growth, thereby improving the battery's discharge capacity and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is used as negative active material under high-temperature and high-pressure conditions, then ionic conductivity is improved, but the lithium metal behaves like a gel causing deformation and short-circuits
Solution Approach 1:
The patent uses a composite negative electrode layer combining lithium metal composite (LMC) with carbon materials. The LMC provides high ionic conductivity while the carbon matrix prevents gel-like deformation, resolving the contradiction between improving conductivity and maintaining structural stability under pressing conditions.
Solution Approach 2:
The patent changes the physical state of lithium from pure metal to a composite material with modified mechanical properties. By altering the composition and structure parameters of the negative electrode, the lithium maintains its electrochemical activity while gaining dimensional stability to prevent short-circuits during battery assembly.
2Reliability
If pressing process is applied to activate sulfide-based solid electrolyte, then ionic conductivity is improved, but lithium metal deforms and causes short-circuits
Solution Approach 1:
The composite structure of LMC embedded in carbon matrix provides both the ionic conductivity needed for battery performance and the mechanical rigidity to withstand pressing without deformation. This resolves the contradiction between achieving high ionic conductivity through pressing and maintaining manufacturing precision.
3Stability of the object's composition
If carbon layer is added to prevent liquefaction, then structural stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the protective carbon layer function with the active lithium-containing layer into a single integrated composite structure. The carbon matrix serves dual purposes: preventing lithium liquefaction and providing structural stability, while simultaneously acting as a conductive network. This reduces device complexity compared to separate layered structures.
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 LMC layer prevents deformation and short-circuits during the pressing process, increases the battery's lifespan by acting as an additional Li reservoir, and enhances discharge capacity by reducing lithium loss through side reactions, resulting in improved performance and longevity.
Implementation Method 1
A negative electrode layer comprising a lithium metal composite (LMC) with high elasticity and hardness is introduced
Implementation Method 2
A negative electrode layer comprising a lithium metal composite (LMC) with high elasticity and hardness is introduced
Implementation Method 3
allowing for uniform lithium nucleation and growth
Implementation Method 4
increases the battery's lifespan by acting as an additional Li reservoir
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Provided are a negative electrode layer for sulfide-based solid electrolyte-containing all-solid secondary batteries, an all-solid secondary battery including the same, and a preparation method thereof, wherein the negative electrode layer includes a negative current collector and a first negative active material layer, and the first negative active material layer includes a lithium metal composite including lithium metal and an inorganic negative active material.