Anode-Free Lithium Battery Electrolyte for Oxide Layer Prevention
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Solution Overview
Problem
Lithium metal batteries face challenges due to the high reactivity of lithium, which leads to the formation of an oxide layer, reducing battery stability and capacity.
Innovation Solution
A lithium secondary battery with a negative electrode free structure is developed, where lithium metal is formed on a negative electrode current collector after charging, and a sacrificial salt with an oxidation potential of 5 V or less is included in the electrolyte to enhance stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as a negative electrode active material to achieve high theoretical capacity and high energy density, then battery capacity and energy density are improved, but lithium metal forms an oxide layer when exposed to atmosphere due to high reactivity, reducing battery stability and reliability
Solution Approach 1:
The patent applies preliminary action by forming a protective layer on the lithium metal surface before the lithium is exposed to the atmosphere during battery assembly. This protective layer is created in advance during the manufacturing process, preventing the formation of harmful oxide layers that would otherwise reduce battery stability and reliability while maintaining the high energy density benefits of lithium metal.
2Ease of manufacture
If lithium metal is exposed to atmosphere during battery assembly, then manufacturing process is simplified, but an oxide layer forms on lithium metal surface, increasing internal resistance and reducing battery performance
Solution Approach 1:
The patent introduces an intermediary protective layer between the lithium metal and the atmosphere during assembly. This protective layer acts as a mediator that allows the manufacturing process to proceed without requiring complete atmosphere exclusion, while still preventing oxide layer formation on the lithium metal surface, thus maintaining both manufacturing simplicity and preventing harmful oxidation.
3Reliability
If a protective layer is formed on lithium metal to prevent oxide layer formation, then battery stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness, composition, and properties of the protective layer to achieve the minimum necessary protection against oxidation. By carefully controlling these parameters, the protective layer provides sufficient stability improvement while minimizing the added manufacturing complexity, finding an optimal balance between reliability enhancement and process simplicity.
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 solution effectively blocks the lithium metal from contacting the atmosphere, preventing oxide layer formation and improving the battery's cycle lifetime and capacity retention.
Implementation Method 1
lithium metal is formed on a negative electrode current collector by lithium ions migrating toward the negative electrode current collector after charge
Implementation Method 2
the electrolyte includes a sacrificial salt having an oxidation potential of 5 V or less with respect to lithium
Data Source
AI summary
A lithium secondary battery including a positive electrode, a negative electrode comprising a negative electrode current collector, and an electrolyte interposed between the positive electrode and negative electrode. The lithium metal is formed on the negative electrode current collector by lithium ions migrating toward the negative electrode current collector after charge. The electrolyte comprises a sacrificial salt having an oxidation potential of 5 V or less with respect to lithium. The lithium secondary battery forms lithium metal while being blocked from the atmosphere, and thereby improves an existing problem caused by high reactivity of lithium metal. By including a sacrificial salt in an electrolyte, lithium consumption caused by an irreversible reaction of a negative electrode is reduced, which may prevent decline in the battery capacity and lifetime properties.