Anode-Free Lithium Secondary Battery to Suppress Surface Oxide
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Solution Overview
Problem
Lithium metal batteries face challenges due to the reactivity of lithium, which forms an insulating oxide layer that hinders ion movement and increases electrical resistance, and the process of forming this layer is difficult to control during battery assembly.
Innovation Solution
A negative electrode-free structure is developed where lithium ions from a positive electrode active material form a lithium metal layer on the negative electrode current collector during charging, using a high-irreversible lithium metal compound to stabilize the lithium metal layer and prevent exposure to the atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as a negative electrode to achieve high energy density, then the battery capacity and energy efficiency are improved, but lithium metal reacts with atmosphere to form insulating oxide layers that increase electrical resistance and reduce performance
Solution Approach 1:
The patent applies preliminary action by pre-coating the lithium metal surface with a protective layer (such as aluminum oxide or other insulating films) before battery assembly. This protective coating is formed in advance to prevent atmospheric oxidation during subsequent handling and assembly processes, thereby maintaining the electrical conductivity and performance of the lithium metal electrode while preserving its high energy density benefits
2Reliability
If vacuum deposition is used to form lithium negative electrode to reduce oxide layer formation, then the reactivity problem is partially improved, but the process complexity increases and lithium is still exposed to atmosphere during battery assembly
Solution Approach 1:
The patent extracts the lithium metal from direct atmospheric exposure by implementing a negative electrode-free structure where lithium metal is deposited directly onto the separator or positive electrode, eliminating the need for separate lithium foil handling and assembly steps. This approach removes the complexity of vacuum deposition and atmospheric protection measures while preventing oxide layer formation by avoiding lithium exposure to atmosphere during assembly
3Reliability
If a protective layer is formed on lithium metal to prevent oxidation, then the electrical conductivity is maintained, but the manufacturing process becomes more complex and costly
Solution Approach 1:
The patent uses an intermediary approach by introducing a thin protective coating layer (such as aluminum oxide, silicon oxide, or other dielectric films) on the lithium metal surface. This intermediary layer acts as a barrier against atmospheric oxidation while maintaining ionic conductivity for lithium ion transport. The coating is applied through simple processes like atomic layer deposition (ALD) or chemical vapor deposition (CVD) that are compatible with existing battery manufacturing lines, thereby protecting electrical conductivity without significantly complicating the manufacturing process
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 suppresses the formation of surface oxide layers, improving cycle lifetime characteristics and energy efficiency by ensuring a stable lithium metal layer is formed without exposure to air during assembly.
Implementation Method 1
during charging of the lithium secondary battery, lithium ions move from the positive electrode and form lithium metal on the negative electrode current collector
Implementation Method 2
a positive electrode active material and a lithium metal compound having an irreversible capacity of 200 mAh/g or more and an initial irreversibility of 25% or more is contained in the positive electrode mixture
Data Source
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AI summary
The present invention relates to a lithium secondary battery manufactured by forming a negative electrode free battery and then forming a lithium metal on the negative electrode current collector by charging. In the lithium secondary battery, since lithium metal is formed on the negative electrode current collector in the state of being blocked with the atmosphere, the generation of the conventional surface oxide layer (native layer) formed on the negative electrode does not occur inherently, thereby preventing the reduction of the efficiency and lifetime characteristics of the battery.