Core-Shell Anode Material for Lithium Battery Volume Expansion Control
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Solution Overview
Problem
Current anode active materials for lithium secondary batteries face challenges with cycle characteristics and volume expansion, particularly due to reactions between lithium sources and (quasi)metal oxides, leading to by-product formation and safety issues, such as fire hazards and low initial efficiency.
Innovation Solution
A core-shell structured anode active material (MOx-Liy)-C is developed, where a carbon shell is coated over a (quasi)metal oxide core, with thermal treatment to form an alloyed (quasi)metal oxide-Li composite, preventing by-product formation and enhancing cycle stability and initial efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If (quasi)metal oxide is prealloyed with lithium to increase initial efficiency, then irreversible phase production is reduced, but by-product formation occurs and gelation issues arise in slurry fabrication
Solution Approach 1:
A lithium salt containing oxygen (such as lithium acetate, lithium formate, or lithium propionate) is introduced as an intermediary substance to facilitate the pre-alloying of lithium with (quasi)metal oxide. This intermediary enables controlled lithium insertion while avoiding direct harmful reactions between lithium metal and (quasi)metal oxide, thereby preventing by-product formation and gelation issues while still achieving reduced irreversible phase production and improved initial efficiency
Solution Approach 2:
The invention changes the chemical parameters of the lithium source from pure lithium metal to lithium salts containing oxygen (acetate, formate, propionate). This parameter change allows for controlled decomposition that releases lithium in a manner that pre-alloys with (quasi)metal oxide without forming harmful by-products or causing gelation, thus resolving the contradiction between improving initial efficiency and avoiding harmful by-products
2Reliability
If lithium metal is used as lithium source for pre-alloying, then initial efficiency increases, but reactivity with water and fire hazards increase
Solution Approach 1:
The invention replaces stable but hazardous lithium metal with lithium salts containing oxygen that decompose at processing temperatures. These salts serve as a disposable precursor that releases lithium in a controlled manner during thermal treatment, achieving the same pre-alloying effect without the persistent fire hazards and water reactivity of metallic lithium
Solution Approach 2:
The invention changes the physical and chemical state of the lithium source from metallic lithium (highly reactive, fire-hazardous) to lithium salts containing oxygen (thermally decomposable, safer). This parameter change maintains the functional benefit of lithium insertion for improving initial efficiency while eliminating the harmful fire hazards and water reactivity associated with lithium metal
3Duration of action of stationary object
If (quasi)metal oxide is used to improve cycle characteristics, then volume expansion is controlled, but initial efficiency decreases due to irreversible phase formation
Solution Approach 1:
The invention applies preliminary action by pre-alloying lithium with (quasi)metal oxide before battery assembly through thermal treatment of lithium salts with the oxide. This pre-alloying reduces the formation of irreversible phases during initial charging cycles, thereby improving initial efficiency while preserving the cycle characteristic benefits of (quasi)metal oxide
Solution Approach 2:
The invention changes the oxygen content parameter of the (quasi)metal oxide by introducing lithium salts containing oxygen during thermal treatment. This parameter adjustment optimizes the composition to reduce irreversible phase formation while maintaining the structural benefits of (quasi)metal oxide for good cycle characteristics, thus resolving the contradiction between initial efficiency and cycle stability
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 provides an anode active material with improved capacity, cycle characteristics, and volume expansion control, achieving high initial efficiency and reduced risk of battery faults.
Implementation Method 1
thermally treating the mixture so as to yield alloyed (quasi)metal oxide-Li in the core
Implementation Method 2
thermally treating the mixture so as to yield alloyed (quasi)metal oxide-Li in the core
Implementation Method 3
coating a shell including a carbon material on a surface of a core including oxide of a (quasi)metal
Data Source
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AI summary
The present disclosure relates to an anode active material comprising a composite of a core-shell structure, a lithium secondary battery comprising the same, and a method of manufacturing the anode active material. According to an aspect of the present disclosure, there is provided an anode active material of a core-shell structure comprising a core including alloyed (quasi)metal oxide-Li (MOx-Liy) and a shell including a carbon material coated on a surface of the core. According to another aspect of the present disclosure, there is provided a method of manufacturing the anode active material of the core-shell structure. According to an aspect of the present disclosure, an anode active material with high capacity, excellent cycle characteristics and volume expansion control capacity, and high initial efficiency is provided.