Lithium Battery Anode Active Material with Alkylene Oxide Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium batteries using carbon-based anode active materials face limitations in capacity and cycle life due to irreversible charge/discharge reactions and volume changes in metal-based materials, leading to rapid capacity degradation and short cycle lives.
Innovation Solution
An anode active material with a surface layer of substituted or unsubstituted alkylene oxide repeating units, such as polyethylene glycol, is applied to metal particles that can be alloyed with lithium, absorbing volume expansion and preventing aggregation, thereby enhancing capacity retention and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-based anode active materials (such as silicon or tin) are used to increase capacity, then the battery capacity and energy density are improved, but the cycle life deteriorates due to volume expansion and contraction during charge/discharge cycles
Solution Approach 1:
The patent applies the nesting principle by placing metal particles (silicon, tin, or their alloys) inside carbon particles. The carbon particle acts as a container or shell that encapsulates the metal core. This nested structure allows the metal to expand and contract during lithium alloying/dealloying while the carbon shell maintains structural integrity and prevents particle detachment, thereby resolving the contradiction between high capacity and long cycle life.
Solution Approach 2:
The patent creates a composite material structure where metal particles are embedded within carbon particles to form a core-shell composite. The composite combines the high capacity advantage of metal-based materials with the structural stability and conductivity of carbon-based materials. This composite structure enables the battery to achieve both high capacity retention and long cycle life by synergistically combining the properties of both materials.
2Quantity of substance
If inorganic particles such as silicon or tin are used as anode active material, then high theoretical capacity is achieved, but the electronic conduction network degrades due to volume changes during charge/discharge
Solution Approach 1:
The nesting of metal particles within carbon particles provides a protective environment that maintains the electronic conduction network. The carbon shell remains structurally stable during volume changes, preserving the conductive pathways for electron transport while the metal core undergoes expansion and contraction. This prevents the degradation of electronic conduction that would otherwise occur with pure metal particles.
Solution Approach 2:
The carbon shell acting as a flexible container accommodates the volume changes of the metal core during charge/discharge cycles. The carbon shell's flexibility allows it to deform with the expanding and contracting metal particles without breaking, thereby maintaining continuous electronic conduction pathways and preventing the formation of insulating spaces between particles.
3Ease of manufacture
If simple mixing of metal powder, carbon powder, and binder is used to create anode active material, then manufacturing is simplified, but stress from particle expansion and contraction causes serious interruption of electronic conduction
Solution Approach 1:
The patent creates a pre-formed composite material where metal particles are already embedded within carbon particles before being mixed with binder. This core-shell composite structure ensures that the metal and carbon are intimately associated at the particle level, maintaining electronic conduction even when subjected to expansion and contraction stresses during cycling. The composite structure provides inherent mechanical stability that simple mixing cannot achieve.
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 modified anode active material maintains high capacity and improves cycle properties by absorbing volume expansion and preventing electronic insulation, resulting in a lithium battery with extended cycle life.
Implementation Method 1
the material layer comprises substituted or unsubstituted alkylene oxide repeating units... absorbing volume expansion and preventing aggregation
Data Source
AI summary
An anode active material and a lithium battery employing the same are provided. In one embodiment of the anode active material, a —(CH2CH2O)— repeating unit is bonded to the surface of metal particles that contain metals that can be alloyed with lithium. The repeating unit prevents reactions between the metal particles and the electrolyte solution. Also, due to its elasticity, the repeating unit absorbs part of the volume expansion of the metal particles. The repeating unit also prevents the metal particles from condensing, thereby enhancing dispersion properties. Accordingly, the inventive anode active material has high capacity and excellent capacity retention during repeated charging and discharging, thereby providing a lithium battery with a long cycle life.