Anode Slurry Binder Relieves Silicon Oxide Volume Expansion
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Solution Overview
Problem
Lithium intercalation and disintercalation in anode active materials cause volume expansion, leading to weakened adhesiveness of polymer binders and impaired charging and discharging characteristics in electrochemical devices, particularly in silicon oxide-based anode active materials.
Innovation Solution
A slurry comprising an anode active material, a polymer binder of styrene butadiene rubber and potassium polyacrylate, a conductive material, and a dispersing medium, with potassium polyacrylate produced by neutralization of polyacrylic acid and potassium hydroxide, is used to form an anode active material layer with high peeling force and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polymer binder is used to form an anode active material layer, then the layer can be formed with adequate adhesion, but the volume expansion of the anode active material during lithium intercalation and disintercalation weakens the adhesiveness of the polymer binder, impairing the conductive structure and deteriorating charging and discharging characteristics and life characteristics
Solution Approach 1:
The patent uses a composite polymer binder system comprising both a first polymer binder and a second polymer binder with different functional properties. The first polymer binder provides initial adhesion, while the second polymer binder maintains adhesion during volume expansion cycles. This composite approach allows the binder system to accommodate the volume expansion of silicon oxide-based anode active materials without losing adhesiveness, thereby maintaining conductive structure integrity and improving charging/discharging characteristics and life characteristics.
2Ease of manufacture
If a polymer binder with relatively lower weight-average molecular weight is used, then the slurry can be processed more easily, but the peeling force of the anode active material layer is reduced
Solution Approach 1:
The patent employs a composite polymer binder system where the first polymer binder (with relatively lower weight-average molecular weight) ensures good processability and slurry flow characteristics, while the second polymer binder compensates for the reduced peeling force by providing enhanced adhesive properties. This combination allows the slurry to be easily processed while maintaining high peeling force in the final anode active material layer.
3Quantity of substance
If silicon oxide-based anode active material is used to increase capacity density, then the energy density is improved, but the volume expansion during lithium intercalation and disintercalation is more severe, weakening the polymer binder adhesiveness
Solution Approach 1:
The patent specifically addresses the severe volume expansion of silicon oxide-based anode active materials by using a composite polymer binder system. The first polymer binder provides initial adhesion to the silicon oxide particles, while the second polymer binder is specifically designed to maintain adhesion during the severe volume expansion cycles that occur with silicon oxide. This composite approach enables the use of high-capacity-density silicon oxide-based materials while preventing binder failure.
4Use of energy by moving object
If the anode active material undergoes volume expansion during lithium intercalation and disintercalation, then the electrochemical capacity is achieved, but the conductive structure is impaired and the life characteristics are deteriorated
Solution Approach 1:
The patent uses a composite polymer binder system that accommodates the volume expansion of anode active materials during lithium intercalation and disintercalation cycles. The first polymer binder establishes the initial conductive structure, while the second polymer binder maintains the integrity of this structure during repeated expansion and contraction. This ensures that the electrochemical capacity is fully utilized while preventing conductive structure impairment and extending the life characteristics of the electrochemical device.
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 slurry effectively relieves volume expansion of anode active materials, enhancing the life characteristics and peeling force of the anode active material layer, even with a polymer binder of relatively lower weight-average molecular weight, and allows for economic drying of the dispersing medium.
Implementation Method 1
The potassium polyacrylate may be produced by the neutralization reaction of polyacrylic acid and potassium hydroxide (KOH).
Implementation Method 2
Each of the cathode and the anode comprises a current collector and an electrode active material layer formed by coating a slurry that contains an electrode active material, a polymer binder and a dispersing medium on the surface of the current collector, followed by drying.
Data Source
AI summary
The present disclosure relates to an anode active material-containing slurry, an anode using the slurry, and an electrochemical device comprising the anode. More specifically, the present disclosure relates to a slurry comprising an anode active material; a polymer binder comprising styrene butadiene rubber and potassium polyacrylate; a conductive material; and a dispersing medium, an anode using the slurry, and an electrochemical device comprising the anode. The anode active material-containing slurry according to one aspect of the present disclosure can relieve the volume expansion of an anode active material by the intercalation and disintercalation of lithium during cycles of electrochemical devices to improve the durability of an anode active material layer, thereby enhancing the life characteristics of the electrochemical devices, and can form an anode active material layer having a high peeling force even though potassium polyacrylate with a relatively lower weight-average molecular weight is used.