LiCoO2 Positive Electrode Composition for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Rechargeable lithium-ion batteries face challenges in achieving fast recharge times due to high battery resistance and limited energy density, which restricts their application in portable and medical devices, where quick charging is essential.
Innovation Solution
The use of a lithium-ion battery design featuring a negative electrode with Li4Ti5O12 and a positive electrode with LiCoO2, optimized with a specific weight ratio of carbon conductive agents and a binder, such as PVDF, to reduce resistance and enhance energy density, allowing for rapid charging without the need for sub-micron particle sizes or reduced electrode thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional lithium-ion battery design is used, then energy density is maintained, but fast recharge capability is limited due to high battery resistance
Solution Approach 1:
The patent changes the composition parameters of the positive electrode by optimizing the weight ratio of carbon conductive agent to binder (2:3 to 3:2) and the weight ratio of carbon black to graphite (1:9 to 9:1). These parameter changes reduce battery resistance and enable fast charging capability while maintaining energy density, resolving the contradiction between charging speed and battery resistance.
2Speed
If sub-micron particle sizes or reduced electrode thickness are used, then fast charging is achieved, but energy density is reduced
Solution Approach 1:
Instead of changing particle size or electrode thickness, the patent changes the compositional parameters of the positive electrode materials. By optimizing the carbon conductive agent to binder ratio and carbon black to graphite ratio, fast charging is achieved while maintaining conventional particle sizes and electrode thickness, thereby preserving energy density.
Solution Approach 2:
The patent uses a composite carbon conductive agent system combining carbon black and graphite in specific ratios. This composite material approach provides both the electrical conductivity needed for fast charging and the structural integrity to maintain energy density, avoiding the need to reduce particle size or thickness.
3Reliability
If carbon conductive agent and binder ratio is optimized, then resistance is reduced and fast charging is enabled, but electrode formulation complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for the carbon conductive agent to binder weight ratio (2:3 to 3:2) and carbon black to graphite weight ratio (1:9 to 9:1). These defined parameter ranges simplify the formulation process by providing clear targets, reducing the complexity of optimization while achieving low resistance and fast charging capability.
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 enables batteries to charge to greater than 90% state-of-charge in under 15 minutes, offering a balance between high energy density and fast recharge capability, with stable resistance and mechanical properties, improving the usability of lithium-ion batteries in devices requiring quick charging.
Implementation Method 1
The positive electrode further comprises a carbon conductive agent and a binder. A weight ratio of the carbon conductive agent to the binder is in a range of about 2:3 to about 3:2
Implementation Method 2
A rechargeable lithium-ion battery comprising a negative electrode comprising a first active material comprising Li4Ti5O12. A positive electrode comprises a second active material comprising LiCoO2
Data Source
AI summary
A rechargeable lithium-ion battery includes a positive electrode enabling fast charging. A negative electrode has a first active material including Li4Ti5O12. A positive electrode includes a second active material including LiCoO2. The positive electrode further includes a carbon conductive agent and a binder. A weight ratio of the carbon conductive agent to the binder is in a range of about 2:3 to about 3:2.