Polyanionic Cathode Graphite Oxide Composite Conductivity
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Solution Overview
Problem
Current polyanionic positive electrode active materials in lithium ion batteries have low electron conductivity, limiting their capacity and output, and existing methods for enhancing conductivity, such as adding conductive additives or forming composites with graphite oxide, do not achieve adequate results due to low affinity or poor crystallinity.
Innovation Solution
A method involving the formation of polyanionic positive electrode active material precursor-graphite oxide composite granulated bodies, where the precursor is mixed with graphite oxide and heated at 500°C or higher in an inert atmosphere, resulting in a composite with a large contact area and high electron conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polyanionic positive electrode active materials are used to achieve high capacity, then battery capacity is improved, but electron conductivity is insufficient leading to limited output
Solution Approach 1:
The patent creates a composite material consisting of polyanionic positive electrode active material particles combined with graphite oxide. This composite structure allows the system to simultaneously achieve high capacity from the polyanionic material and improved electron conductivity from the graphite oxide component, resolving the contradiction between capacity and power.
2Power
If conductive additives are added to enhance electron conductivity, then output is improved, but affinity between additives and active material is low limiting effectiveness
Solution Approach 1:
Graphite oxide serves as an intermediary substance between the polyanionic active material particles. It forms a coating or composite structure that provides excellent electron conductivity while having high affinity for the active material surface, effectively mediating the electrical connection between particles and resolving the affinity problem with conventional conductive additives.
3Power
If composites with graphite oxide are formed to improve conductivity, then electron conductivity is enhanced, but contact area between materials is insufficient
Solution Approach 1:
The patent applies graphite oxide locally on the surface of polyanionic active material particles, creating a coating structure where the conductive material is concentrated at the critical interface regions. This local application ensures maximum contact area between conductive and active materials, optimizing electron conductivity without requiring bulk mixing.
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 approach produces active material composite particles with high electron and ionic conductivity, enhancing the capacity and power of lithium ion batteries by forming a compact composite with a high contact area between the polyanionic active material and graphene.
Implementation Method 1
a step 2 wherein the precursor composite granulated bodies obtained in the step 1 are heated at 500° C. or higher in an inert atmosphere or in a reducing atmosphere
Implementation Method 2
a step 2 wherein the precursor composite granulated bodies obtained in the step 1 are heated at 500° C. or higher in an inert atmosphere or in a reducing atmosphere
Data Source
AI summary
A method is provided for producing polyanionic positive electrode active material composite particles, which comprises: a step 1 wherein precursor composite granulated bodies, each of which contains a polyanionic positive electrode active material precursor particle in graphite oxide, are formed by mixing a polyanionic positive electrode active material precursor and graphite oxide; and a step 2 wherein the precursor composite granulated bodies obtained in step 1 are heated at 500° C. or higher in an inert atmosphere or in a reducing atmosphere. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is less than 50% of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material. The maximum intensity of the X-ray diffraction peak based on the positive electrode active material is 50% or more of the maximum intensity of the X-ray diffraction peak based on the materials other than the positive electrode active material.