Non-graphitizable Carbon Negative Electrode for Energy Storage
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Solution Overview
Problem
Conventional energy storage devices experience transient power degradation after high-rate cycles due to reduced separator thickness, leading to temporary power reduction and potential micro short-circuits.
Innovation Solution
Incorporating a negative electrode with non-graphitizable carbon having a particle diameter of 2.0 μm to 6.0 μm and a corrected negative electrode density of 1.2 to 5.1 g/cm3, along with a separator with a PC impregnation ratio of 40% to 70%, to reduce the influence of the separator on the negative electrode and enhance current distribution uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the thickness of the separator is reduced to increase power and capacity, then the power and capacity of the energy storage device are improved, but transient power degradation occurs after high-rate cycles
Solution Approach 1:
The patent changes the particle diameter parameter of non-graphitizable carbon to a specific range (2.0 μm to 6.0 μm) and adjusts the corrected negative electrode density to 1.2 to 5.1 g/cm³. These parameter changes optimize the negative electrode structure to suppress transient power degradation while maintaining high power and capacity, resolving the contradiction between power improvement and reliability maintenance.
Solution Approach 2:
The patent uses composite materials by combining non-graphitizable carbon with specific particle size distribution and density characteristics in the negative electrode. This composite structure, when paired with a reduced-thickness separator, achieves both high power/capacity and suppresses transient power degradation, resolving the technical contradiction.
2Power
If the thickness of the separator is reduced, then the power and capacity are increased, but micro short-circuits may occur
Solution Approach 1:
By optimizing the particle diameter of non-graphitizable carbon (2.0 μm to 6.0 μm) and the corrected negative electrode density (1.2 to 5.1 g/cm³), the patent creates a negative electrode structure that maintains stability during charge-discharge cycles. This prevents electrode expansion/contraction that could cause micro short-circuits in reduced-thickness separators, allowing power and capacity increases without harmful effects.
Solution Approach 2:
The patent prepares the negative electrode with optimized non-graphitizable carbon properties beforehand to cushion against the mechanical stress and volume changes that occur during high-rate charge-discharge. This pre-optimization prevents the electrode from deforming in ways that would cause micro short-circuits with thin separators.
3Productivity
If high-rate charge-discharge is performed repeatedly, then the power output is maintained, but transient power degradation occurs
Solution Approach 1:
The patent optimizes the particle diameter of non-graphitizable carbon (2.0 μm to 6.0 μm) and corrected negative electrode density (1.2 to 5.1 g/cm³) to enable the negative electrode to withstand repeated high-rate charge-discharge cycles. This parameter optimization ensures uniform current distribution and prevents transient power degradation, allowing sustained high-rate productivity without reliability loss.
Solution Approach 2:
The patent creates a dynamic-compatible negative electrode structure using non-graphitizable carbon with specific particle size and density characteristics. This structure can dynamically adapt to the stress and strain of repeated high-rate cycles without degrading, maintaining both productivity and reliability over time.
Data Source
AI summary
An energy storage device comprises a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and a nonaqueous electrolyte. The negative electrode has a negative substrate layer, and a negative composite layer arranged on the surface of the negative substrate layer. The separator has a separator substrate layer. The negative composite layer contains a non-graphitizable carbon having a particle diameter D50 of 2.0 μm or more and 6.0 μm or less. A corrected negative electrode density, which is defined as a value obtained by dividing, by a thickness of the separator substrate layer, a value obtained by multiplying a density of the negative composite layer by a thickness of the negative composite layer, is 1.2 (g/cm3) or more and 5.1 (g/cm3) or less.