In-Battery Polymerization of Conducting Polymers for High-Rate Cathodes
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Solution Overview
Problem
Existing cathodes for fast charge lithium ion batteries, particularly those with olivine LiFePO4 (LFP) materials, exhibit poor kinetic response and electronic and ionic transfer under rapid-rate conditions due to their nano-scale nature and carbon coating, limiting their performance in terms of capacity, rate capability, and cyclability.
Innovation Solution
A cathode formulation comprising spinel or layered structure materials, up to 10 wt% olivine-based structure material, a binder, and monomer/oligomer that polymerizes into a conductive polymer during the first charging cycle, allowing in-situ polymerization within the cell to create a conductive polymer matrix, enhancing electronic conductivity and ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If LFP particles are used with nano-scale and carbon coating, then capacity and cyclability are improved, but kinetic response and electronic/Lit-ion transfer under rapid-rate conditions deteriorate
Solution Approach 1:
The patent creates a composite structure by in-situ polymerization of conductive polymers on LFP particle surfaces. The conductive polymer coating forms a composite material that combines the high capacity and cyclability of LFP with enhanced electronic conductivity, resolving the contradiction between long cycle life and rapid-rate kinetic response
Solution Approach 2:
The patent changes the electronic conductivity parameter of the LFP cathode by introducing conductive polymer coatings through in-situ polymerization. This parameter change enables rapid electron transfer while preserving the underlying LFP structure's cyclability, allowing high-rate charging without sacrificing cycle life
2Ease of manufacture
If conventional cathode materials are used, then manufacturing simplicity is maintained, but rate capability and capacity at high charging rates deteriorate
Solution Approach 1:
The patent employs in-situ polymerization where the conductive polymer forms automatically during the first charging cycle within the battery cell. This self-service approach eliminates separate polymerization manufacturing steps, maintaining ease of manufacture while achieving enhanced rate capability through the formed conductive polymer network
Solution Approach 2:
The patent performs preliminary polymerization action during the first charging cycle to create a conductive polymer matrix before high-rate operation begins. This preliminary action prepares the cathode for subsequent high-rate charging by establishing electron transfer pathways in advance, improving rate capability without adding manufacturing complexity
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 solution significantly improves the cell capacity and cyclability, especially at high charging rates, with cells exhibiting more than threefold capacity compared to prior art cells, and provides a uniform polymer distribution throughout the cathode, enhancing the overall performance of lithium ion batteries.
Implementation Method 1
the partial delithiation is carried out electrochemically during the first charging cycle of the cell
Implementation Method 2
monomer and/or oligomer material selected to polymerize into a conductive polymer upon partial delithiation of the olivine-based structure cathode material
Implementation Method 3
enhancing electronic conductivity and ion diffusion
Implementation Method 4
enhancing electronic conductivity and ion diffusion
Data Source
AI summary
Cathodes for a fast charging lithium ion battery, processes for manufacturing thereof and corresponding batteries are provided. Cathode formulations comprise spinel and/or layered structure cathode material with 5-10% of cathode material having an olivine-based structure as polymerization initiator, binder material, and monomer and/or oligomer material selected to polymerize into a conductive polymer upon partial delithiation of the olivine-based structure cathode material during at least a first charging cycle of a cell having a cathode made of the cathode formulation. When the cathode is used in a battery, polymerization is induced in-situ (in-cell) during first charging cycle(s) of the battery to provide a polymer matrix which is evenly dispersed throughout the cathode.