Lithium Alloy Anode Coating for Battery Cycle Life
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Solution Overview
Problem
Lithium alloy anodes in batteries experience cracking due to expansion and shrinkage during charge and discharge cycles, leading to reduced electronic conduction and insufficient cycle characteristics due to increased surface area and particle breakage.
Innovation Solution
Incorporating a light metallic salt with a M-X bond, where M represents a transition metal or 3B Group element and X represents oxygen or sulfur, in the electrolyte, and using an anode active material alloyed with the current collector, formed by methods like vapor-phase deposition or sintering, to inhibit decomposition reactions and improve charge and discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium alloy is used for anode to achieve high energy density, then capacity is improved, but cycle characteristics deteriorate due to particle cracking and electronic conduction loss
Solution Approach 1:
A coating layer comprising a compound containing metal element M (transition metal, 3B-5B group) and element X (oxygen, sulfur, or halogen) is introduced as an intermediary between the lithium alloy anode particles and the electrolyte. This coating layer mediates the interaction by preventing direct contact and decomposition reactions while allowing lithium ion insertion/extraction, thereby maintaining high capacity while improving cycle characteristics.
Solution Approach 2:
The invention changes the chemical composition and structure of the anode surface by forming a specific coating layer with controlled stoichiometry (e.g., M:X ratios). This parameter change creates a stable surface that resists cracking and maintains electronic conduction, resolving the contradiction between high capacity and cycle life.
2Quantity of substance
If lithium alloy particles are used for anode to achieve high capacity, then energy density is improved, but electronic conduction deteriorates due to particle breakage
Solution Approach 1:
The coating layer acts as an intermediary that maintains electronic conduction pathways. By comprising compounds with specific metal elements (transition metals, 3B-5B group elements) and elements X (oxygen, sulfur, halogens), the coating preserves electron transport while protecting against particle fragmentation, thus preventing energy loss despite high capacity utilization.
3Quantity of substance
If lithium alloy anode is used to achieve high capacity, then energy density is improved, but decomposition reaction increases leading to insufficient cycle characteristics
Solution Approach 1:
The coating layer comprising compounds of metal element M and element X serves as a protective intermediary that physically separates the lithium alloy anode from the electrolyte. This prevents direct decomposition reactions between the anode and electrolyte while still permitting lithium ion transport, thereby eliminating harmful decomposition effects while maintaining high capacity.
Solution Approach 2:
The coating layer creates an inert chemical environment at the anode surface by using compounds with high chemical stability (transition metal compounds, compounds of 3B-5B group elements with oxygen, sulfur, or halogens). This inert environment prevents unwanted decomposition reactions while allowing the anode to function at high capacity.
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 configuration enhances battery capacity, charge and discharge efficiency, and cycle characteristics, while reducing internal resistance and improving heavy load characteristics.
Implementation Method 1
the lithium alloy is cracked into small pieces due to its intense expansion and shrinkage after repeating charge and discharge
Implementation Method 2
decomposition reaction of the electrolyte can be inhibited even in the following cases
Data Source
AI summary
A battery is provided which has a high capacity and can improve battery characteristics, such as cycle characteristics. The battery includes a spirally wound electrode body, wherein a cathode and an anode are wound with a separator in between. The anode includes, for example, simple substances, alloys, compounds of metal elements or metalloid elements capable of forming an alloy with Li, the like and combinations thereof. An electrolytic solution wherein an electrolyte salt is dissolved in a solvent is impregnated in the separator. For the electrolyte salt, a light metallic salt having B—O bond or P—O bond, such as difluoro[oxalato-O,O′]lithium borate and tetra fluoro[oxalato-O,O′]lithium phosphate, can be used. By forming a stable coating, decomposition reaction of the solvent can be inhibited, and reaction between the anode and the solvent can be prevented.