Fluoflavin Polymer Electrode Material for High-Rate Li-Ion Batteries
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in achieving high rate characteristics and cycle stability due to limitations in electron conductivity and volume expansion issues with Si-based negative electrodes, and the high energy density can lead to safety concerns such as overheating and fire risks.
Innovation Solution
An electrode material containing a small amount of polymer with a fluoflavine skeleton in combination with an inorganic active material, which improves both rate and cycle characteristics by enhancing charge storage ability and reducing the need for high-temperature carbonization processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the amount of conductive auxiliary agent (carbon material) is increased to improve electron conductivity in the positive electrode, then electron conductivity is improved, but the amount of active material decreases, whereby the capacity of the battery decreases
Solution Approach 1:
The patent uses a polymer compound with specific functional groups (carboxyl, hydroxyl, or amine groups) as an intermediary substance that binds to the surface of the positive electrode active material particles. This polymer layer acts as a mediator that provides electron conductivity without requiring large amounts of carbonaceous material, thus maintaining both conductivity and capacity.
Solution Approach 2:
The patent changes the chemical parameters of the electrode surface by introducing polymers with specific functional groups that can form coordinate bonds or hydrogen bonds with the active material surface. This chemical modification provides conductivity through the polymer's electronic structure rather than through carbonaceous networks, allowing lower overall carbon content while maintaining conductivity.
2Quantity of substance
If high energy density is achieved to improve battery capacity, then capacity is improved, but the risk of overheating or fire accidents increases
Solution Approach 1:
The polymer compound serves as a protective intermediary layer on the positive electrode surface that facilitates safe energy storage and release. The functional groups on the polymer can interact with the active material surface to stabilize the electrode structure during charge-discharge cycles, reducing the risk of thermal runaway while maintaining high capacity.
Solution Approach 2:
The patent employs polymer compounds with stable chemical structures that create a protective environment around the active material particles. This polymer layer acts as a chemically stable interface that prevents unwanted side reactions and thermal degradation, effectively creating a safe operational environment for high-energy-density materials.
3Power
If carbonization treatment is performed at high temperature (500-800°C) to form carbonaceous film for improving electron conductivity, then electron conductivity is improved, but the capacity of the electrode is reduced and the process requires long-time heat treatment
Solution Approach 1:
The patent replaces the thermal carbonization process with a chemical bonding approach. Instead of using high-temperature heat treatment to carbonize organic compounds, the invention directly applies polymer compounds with functional groups that can chemically bond to the active material surface at lower temperatures, eliminating the need for prolonged high-temperature processing while achieving similar or better conductivity enhancement.
4Quantity of substance
If Si or Si alloy is used as negative electrode active material to achieve high capacity per unit weight, then capacity is improved, but volume expansion increases, which causes deteriorated cycle characteristics
Solution Approach 1:
The patent employs polymer compounds that form flexible coating layers on the surface of negative electrode active material particles. These polymer films can accommodate the volume expansion of Si-based materials during lithiation while maintaining structural integrity, thus preventing particle disintegration and maintaining good cycle characteristics despite the high capacity of Si-based materials.
Data Source
AI summary
Provided is an electrode material which is suitable for use as a material for forming electrodes for use in lithium ion secondary batteries, etc. and which makes it possible to heighten the rate characteristics of batteries. The electrode material is characterized by comprising a polymer having, in a side chain, a fluoflavin skeleton such as that shown by the formula and an inorganic active material, the polymer being contained in an amount of 1 mass % or less with respect to the solid components.