Lithium Secondary Battery Anode Alloy for Capacity Retention
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Solution Overview
Problem
Lithium secondary batteries face reduced capacity retention due to deactivation of lithium metal caused by volume changes during charging and discharging, leading to decreased conductivity and resistance increases at low temperatures.
Innovation Solution
Incorporating a negative electrode layer with an alloy of lithium metal and a dissimilar metal, along with an oxygen-enriched portion, to enhance the affinity with the separator and reduce electrolyte resistance, while utilizing deposition and dissolution reactions to minimize crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If lithium metal is used as a negative electrode active material, then high output voltage is achieved, but capacity retention rate is reduced due to deactivation caused by volume change during charging and discharging
Solution Approach 1:
The patent changes the physical and chemical parameters of the negative electrode by forming an alloy between lithium metal and dissimilar metal. This alloying modifies the volume expansion characteristics and electrochemical properties of lithium metal, enabling it to maintain structural integrity during charging and discharging cycles while preserving high output voltage performance
Solution Approach 2:
The patent creates a composite negative electrode material by combining lithium metal with dissimilar metal to form an alloy. This composite structure leverages the high capacity of lithium metal while the dissimilar metal component provides structural stability and reduces deactivation, thereby improving capacity retention rate without sacrificing output voltage
2Use of energy by moving object
If lithium metal undergoes volume change during charging and discharging, then deposition and dissolution reactions occur, but cracks are formed and conductivity decreases
Solution Approach 1:
The patent modifies the physical parameters of the negative electrode material by alloying lithium metal with dissimilar metal. This changes the mechanical properties and volume expansion behavior, allowing the material to undergo deposition and dissolution reactions while maintaining structural integrity and preventing crack formation that would reduce conductivity
3Reliability
If oxygen-enriched portion is added to negative electrode layer, then affinity with separator is enhanced and electrolyte resistance is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single negative electrode layer structure. The alloy of lithium metal and dissimilar metal simultaneously provides the electrochemical activity for deposition and dissolution reactions while the oxygen-enriched portion integrated within the same layer enhances separator affinity and reduces electrolyte resistance, avoiding the need for separate functional layers
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
Improves capacity retention rates and maintains high low-temperature output by reducing electrolyte resistance and minimizing inactive crack formation, thereby enhancing the battery's overall performance.
Implementation Method 1
a negative electrode in which deposition and dissolution reactions of lithium metal occur
Implementation Method 2
deactivation of the lithium metal caused by a volume change of the lithium metal during charging and discharging
Data Source
AI summary
A lithium secondary battery includes a positive electrode, and a negative electrode in which deposition and dissolution reactions of lithium metal occur. The negative electrode includes a negative electrode layer. The negative electrode layer contains, as a negative electrode active material, an alloy of the lithium metal and dissimilar metal. An element percentage of lithium element in the alloy is 40.00 atomic % or more and 99.97 atomic % or less when the lithium secondary battery is fully charged.