Lithium Secondary Battery Negative Electrode Free Structure
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Solution Overview
Problem
Lithium metal batteries face challenges due to the reactivity of lithium with water and oxygen, leading to the formation of a surface oxide layer that reduces electrical conductivity and increases electric resistance, making manufacturing and use difficult, especially during battery assembly.
Innovation Solution
A lithium secondary battery design featuring a negative electrode free structure where lithium metal is formed on the negative electrode current collector through lithium ion transfer from the positive electrode during charging, with a protective layer of lithium conducting polymer or inorganic solid electrolyte to prevent atmospheric exposure and oxide layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as negative electrode active material, then weight energy density is improved, but surface oxide layer formation increases due to high reactivity with atmosphere
Solution Approach 1:
The patent applies preliminary action by forming a protective coating layer on the lithium metal surface before battery assembly. This coating is deposited in advance to prevent atmospheric exposure during subsequent handling and assembly processes, thereby preventing oxide layer formation while preserving the high energy density benefits of lithium metal
Solution Approach 2:
The patent creates an inert environment by applying a protective coating that acts as a barrier between the reactive lithium metal and the atmospheric environment. This coating isolates the lithium from oxygen and moisture, effectively creating a protected zone that prevents oxidation while allowing the battery to utilize lithium's high energy density
2Ease of manufacture
If lithium metal is exposed to atmosphere during assembly, then manufacturing process is simplified, but oxide layer formation increases reducing electrical conductivity
Solution Approach 1:
The protective coating is applied in advance during the electrode manufacturing process, before battery assembly begins. This preliminary protection allows subsequent assembly steps to proceed in normal atmospheric conditions without special precautions, maintaining manufacturing simplicity while preventing conductivity degradation from oxide formation
3Object-affected harmful factors
If vacuum deposition process is used to reduce oxide layer, then surface oxide formation is partially improved, but manufacturing complexity increases and fundamental suppression is still impossible
Solution Approach 1:
The patent extracts the protection function from complex vacuum deposition processes and implements it through a simpler coating approach that can be applied in atmospheric conditions. This removes the need for vacuum equipment and complex process control, fundamentally suppressing oxide formation through the protective barrier rather than attempting to prevent oxidation during exposure
Solution Approach 2:
The patent changes the manufacturing parameter from requiring vacuum conditions to allowing atmospheric conditions by using a coating method that cures or stabilizes in air. This parameter change eliminates vacuum deposition equipment requirements while achieving better fundamental protection against oxide layer formation
4Ease of manufacture
If lithium foil is attached on current collector, then negative electrode structure is formed, but reactivity with water and oxygen increases making manufacture and use difficult
Solution Approach 1:
The protective coating is applied to the lithium foil before it is attached to the current collector. This preliminary protection allows the electrode to be assembled and handled in normal atmospheric conditions without special precautions, making manufacture and operation easier while preventing the harmful reactions between lithium and environmental contaminants
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 approach enhances the cycle lifetime and energy efficiency of lithium secondary batteries by preventing surface oxide layer formation, thereby improving the battery's performance and stability during assembly and operation.
Implementation Method 1
lithium metal moved from the positive electrode is formed on the negative electrode current collector through charge
Implementation Method 2
a protective layer formed on a surface in contact with the separator, the protective layer comprising a lithium conducting polymer and/or an inorganic solid electrolyte
Implementation Method 3
the protective layer comprising a lithium conducting polymer and/or an inorganic solid electrolyte
Data Source
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AI summary
The present invention relates to a lithium secondary battery prepared to a negative electrode free battery, and forming lithium metal on a negative electrode current collector through charge. The lithium secondary battery forms lithium metal while being blocked from the atmosphere, and since production of a surface oxide layer (native layer) formed on an existing negative electrode is fundamentally blocked, resulting battery efficiency and lifetime property decline may be prevented.