Conductive Polymer Coating for Battery Energy Density
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Solution Overview
Problem
Lithium secondary batteries have lower power density and shorter service life due to lower electrochemical reaction rates and higher internal resistance, limiting their capacity and energy density, especially when using electrically conductive polymers as positive electrode active materials.
Innovation Solution
A particulate active material for the positive electrode is developed by coating electrically conductive polymer particles with a conductive agent, enhancing electrical conductivity and facilitating ion migration, which increases energy density without requiring a higher proportion of conductive agents, thus improving the performance of power storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrically conductive polymer is used as positive electrode active material, then capacity is improved, but power density deteriorates due to lower electrochemical reaction rate
Solution Approach 1:
The patent applies local quality by coating only the surface of the electrically conductive polymer particles with a conductive agent, rather than blending the conductive agent throughout the entire polymer matrix. This surface coating creates a conductive shell that specifically addresses the electrochemical reaction rate at the particle surface, where ion insertion/desertion occurs, without diluting the overall polymer capacity.
Solution Approach 2:
The patent creates a composite material structure where electrically conductive polymer particles are coated with a conductive agent to form a core-shell structure. This composite approach combines the high capacity of the electrically conductive polymer with the high electrical conductivity of the conductive agent coating, resolving the contradiction between capacity and power density.
2Power
If higher proportion of conductive agent is added to enhance electrical conductivity, then power density is improved, but energy density deteriorates due to increased internal resistance and lower active material content
Solution Approach 1:
By applying the conductive agent only as a surface coating rather than bulk blending, the patent achieves high electrical conductivity at the critical reaction interface while minimizing the amount of conductive agent required. This preserves the high active material content and maintains energy density.
Solution Approach 2:
The patent uses a partial action approach by coating only the outer surface of the polymer particles with the conductive agent, rather than incorporating it throughout the entire material. This provides sufficient conductivity enhancement at the reaction sites without the excessive conductive agent content that would reduce energy density.
3Power
If conductive agent is blended in higher proportion, then electrical conductivity is improved, but manufacturing precision deteriorates due to difficulty in kneading
Solution Approach 1:
The patent segments the conductive agent application to only the particle surface rather than requiring uniform distribution throughout the bulk material. This eliminates the kneading uniformity problems associated with high proportions of conductive agent, as the coating process applies the conductive agent in a controlled manner on particle surfaces.
Solution Approach 2:
The patent uses a coating process as an intermediary method to apply the conductive agent to particle surfaces, avoiding the need for extensive kneading and mixing that would be required for bulk blending. This intermediary coating approach achieves good electrical conductivity without the manufacturing precision issues of high-proportion blending.
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 coated particulate active material significantly enhances the energy density and cycle characteristics of power storage devices, providing a higher weight and volume energy density compared to traditional lithium secondary batteries.
Implementation Method 1
the surfaces of the particles of the electrically conductive polymer are coated with a conductive agent
Implementation Method 2
An electrode for such a power storage device contains an active material which is capable of ion insertion/desertion. The ion insertion/desertion of the active material is also referred to as doping/dedoping
Data Source
AI summary
A particulate active material for a power storage device positive electrode having a higher energy density is provided, which includes particles of an electrically conductive polymer and a conductive agent, wherein the electrically conductive polymer particles each have a surface coated with the conductive agent.