Graphene Oxide Reduction for High-Density Battery Electrodes
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Solution Overview
Problem
Conductive additives like acetylene black in storage battery electrodes lead to high contact resistance and reduced discharge capacity due to point contact and aggregation issues, while graphite additives can introduce impurities, affecting battery performance.
Innovation Solution
Using graphene oxide as a conductive additive, which is reduced to form a graphene network for improved electrical conductivity, allowing for higher active material loading and uniform dispersion through chemical reduction treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acetylene black is used as a conductive additive to improve electrical conductivity, then contact resistance between active material and current collector is reduced, but the amount of active material in the electrode decreases due to the need for higher conductive additive ratios
Solution Approach 1:
The invention changes the physical form of the conductive additive from granular particles to flaky graphite particles with specific dimensional ratios (length 0.5-5 μm, thickness 0.03-0.3 μm). This parameter change allows the conductive additive to form effective conductive networks at lower ratios, thereby maintaining electrical conductivity while increasing the proportion of active material in the electrode.
Solution Approach 2:
The invention creates a composite structure where flaky graphite particles are combined with active material particles in a specific configuration. The flaky shape of graphite allows it to wrap around and connect active material particles, forming a three-dimensional conductive network that efficiently conducts electricity with minimal additive content, thus resolving the contradiction between conductivity and active material quantity.
2Reliability
If the ratio of conductive additive to active material is increased to increase contact points, then electrical conductivity is improved, but the proportion of active material decreases resulting in lower discharge capacity
Solution Approach 1:
By changing the morphology parameter of the conductive additive from granular to flaky with specific aspect ratios, the invention achieves more efficient conductive networks at lower additive ratios. The flaky shape provides larger surface area and better wrapping capability around active material particles, improving conductivity without sacrificing discharge capacity.
Solution Approach 2:
The invention transitions from zero-dimensional granular conductive additives to two-dimensional flaky structures. This dimensional change enables the conductive additive to form extended conductive planes that efficiently connect active material particles across the electrode, achieving high conductivity with minimal material content and preserving discharge capacity.
3Ease of manufacture
If natural graphite is used as a conductive additive to reduce cost, then manufacturing cost is reduced, but impurities such as iron, lead, and copper react with active material or current collector reducing battery potential and capacity
Solution Approach 1:
The invention changes the purity parameter of the graphite conductive additive from natural graphite (containing impurities) to highly purified graphite with controlled composition. This parameter change eliminates harmful impurities while maintaining the cost-effective graphite base material, thus resolving the contradiction between manufacturing cost and battery performance.
Solution Approach 2:
The invention applies local quality control by specifically purifying the graphite conductive additive to remove harmful impurities (Fe, Pb, Cu) while maintaining the beneficial graphite structure. This localized purification ensures that only the necessary carbon structure remains for conductivity, without the harmful reactive impurities, balancing cost and performance.
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 method results in a storage battery electrode with high active material density and increased capacity per unit volume, while using a safer and less toxic reducer like ascorbic acid, facilitating lower temperature reduction and enhanced battery characteristics.
Implementation Method 1
graphene oxide with high dispersibility is used as a raw material and is mixed with an active material and the like to form a mixture, the mixture is provided over a current collector, and then reduction treatment is performed, so that an electrode including graphene as a conductive additive is formed
Implementation Method 2
lithium ions in the secondary battery are transferred between the positive electrode and the negative electrode through the nonaqueous electrolyte and intercalated into or deintercalated from the active materials of the positive electrode and the negative electrode
Implementation Method 3
A binder is mixed into the positive electrode or the negative electrode in order that active materials can be bound or an active material and a current collector can be bound
Data Source
AI summary
To provide a method for forming a storage battery electrode including an active material layer with high density in which the proportion of conductive additive is low and the proportion of the active material is high. To provide a storage battery having a higher capacity per unit volume of an electrode with the use of a storage battery electrode formed by the formation method. A method for forming a storage battery electrode includes the steps of forming a mixture including an active material, graphene oxide, and a binder; providing a mixture over a current collector; and immersing the mixture provided over the current collector in a polar solvent containing a reducer, so that the graphene oxide is reduced.