Secondary Battery Positive Electrode Graphene Conductive Additive
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving both high electrode strength and good battery characteristics due to the use of graphene oxide as a conductive additive, which can lead to decreased adhesion and increased resistance when the amount of graphene is increased, and reduced charge and discharge capacity when the amount is decreased.
Innovation Solution
A positive electrode for a secondary battery is fabricated with a reduced amount of graphene oxide as a conductive additive and a carbon layer on the surface of the active material to enhance conductivity and prevent electrode strength decline, maintaining battery characteristics by adjusting the proportion of graphene and binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of conductive additive (acetylene black) is increased to increase contact points between active material and conductive additive, then electron conductivity is improved, but the proportion of active material in the electrode decreases, resulting in decreased charge and discharge capacity
Solution Approach 1:
The patent changes the physical form parameter of the conductive additive from particulate (acetylene black with several tens to hundreds of nanometers diameter) to sheet-like (graphene with lateral dimensions of several micrometers to several tens of micrometers). This parameter change transforms the contact mode from point contact to surface contact, dramatically improving electron conductivity with much smaller additive amounts, thereby preserving active material proportion and charge/discharge capacity.
Solution Approach 2:
The patent creates a composite structure where sheet-like graphene conducts electrons between particulate active materials. The combination of different morphologies (sheet-like conductor + particulate active material) achieves superior electron transport pathways compared to using only particulate conductive additives, resolving the contradiction between conductivity enhancement and active material content preservation.
2Strength
If the amount of binder is increased to improve adhesion between active material and current collector, then electrode strength is improved, but the proportion of active material in the electrode decreases, resulting in lower charge and discharge capacity
Solution Approach 1:
The patent creates a composite structure where sheet-like graphene conducts electrons between particulate active materials. The combination of different morphologies (sheet-like conductor + particulate active material) achieves superior electron transport pathways compared to using only particulate conductive additives, resolving the contradiction between conductivity enhancement and active material content preservation.
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 approach allows for both good battery characteristics and electrode strength, with a discharge capacity of more than 140 mAh/g at a lower limit voltage of 2 V and a discharge curve with a plateau in 60% or more of the discharge capacity, while preventing electrode separation during the winding test.
Implementation Method 1
graphene oxide is reduced at the same time and a single layer or a stacked layer of graphene as a conductive additive is formed
Implementation Method 2
a carbon layer on the surface of the active material to enhance conductivity
Data Source
AI summary
A positive electrode for a secondary battery which enables both good battery characteristics and electrode strength at a predetermined level, a secondary battery, and a method for fabricating the positive electrode for a secondary battery are provided. The positive electrode for a secondary battery includes a current collector and an active material layer over the current collector. The active material layer includes an active material, graphene, and a binder. A carbon layer is on a surface of the active material. The proportion of the graphene in the active material layer is greater than or equal to 0.1 wt % and less than or equal to 1.0 wt %.