Rechargeable Lithium Battery with Flake Polyethylene and Carbon Nanotubes
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Solution Overview
Problem
Rechargeable lithium batteries face safety concerns due to internal short circuits, which can lead to explosions, and the use of finely pulverized active materials to increase energy density compromises conductivity and power characteristics.
Innovation Solution
A rechargeable lithium battery design incorporating a negative electrode with flake-shaped polyethylene particles and a positive electrode with composite oxides, carbon nanotubes of specific length and diameter ratios, and a balanced active material composition to enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If finely pulverized active material is applied to increase energy density, then battery capacity is improved, but conductivity is lowered and power characteristics deteriorate
Solution Approach 1:
The patent uses composite oxide materials (Li-Mn-Ni-Co-O) combining multiple metal elements to create a positive active material that maintains high capacity while improving conductivity. The composite structure allows synergistic effects among different metals, resolving the contradiction between capacity and conductivity
Solution Approach 2:
The patent optimizes particle size parameters and compositional ratios of the active materials to achieve the right balance between surface area (for capacity) and conductivity. By controlling particle morphology and size distribution, the patent maintains high capacity while preventing excessive conductivity loss
2Reliability
If internal short circuit prevention measures are implemented, then safety is improved, but device complexity increases
Solution Approach 1:
The patent employs self-regulating mechanisms where the battery materials themselves provide safety functions. The specific composite oxide composition and electrode structure inherently prevent thermal runaway and internal short circuits without requiring additional complex safety systems, achieving safety through material properties rather than structural complexity
Solution Approach 2:
The patent uses carefully selected intermediate materials and layer structures between electrodes that act as mediators to prevent direct contact and thermal runaway. These intermediate functional layers provide safety barriers while maintaining electrical connectivity, resolving the contradiction between safety and 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 design achieves high capacity and power characteristics while improving safety by reducing electrode plate resistance and preventing capacity degradation, enabling effective thermal management and shut-down functions.
Implementation Method 1
the negative electrode functional layer includes flake-shaped polyethylene particles
Implementation Method 2
the positive active material layer includes a first positive active material including at least one of a composite oxide of a metal selected from cobalt, manganese, nickel, and a combination thereof and lithium, a second positive active material including a compound represented by Chemical Formula 1, and carbon nanotubes
Data Source
AI summary
A rechargeable lithium battery includes a negative electrode including a negative current collector, a negative active material layer disposed on the negative current collector, and a negative electrode functional layer disposed on the negative active material layer; and positive electrode including a positive current collector and a positive active material layer disposed on the positive current collector, wherein the negative electrode functional layer includes flake-shaped polyethylene particles, the positive active material layer includes a first positive active material including at least one of a composite oxide of a metal selected from cobalt, manganese, nickel, and a combination thereof and lithium, a second positive active material including a compound represented by Chemical Formula 1, and carbon nanotubes, and the carbon nanotubes have an average length of 30 μm to about 100 μm.LiaFe1-x1Mx1PO4 Chemical Formula 1In Chemical Formula 1, 0.90≤a≤1.8, 0≤x1≤0.7, and M is Mn, Co, Ni, or a combination thereof.