PEG-Coated Negative Electrode Sheet for Fast-Charging Thick Batteries
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Solution Overview
Problem
Current negative electrode materials for lithium-ion batteries, such as artificial and natural graphite, face limitations in providing sufficient intercalation channels for lithium ions, hindering fast charging and discharging performance due to their small layer spacing and two-dimensional diffusion method.
Innovation Solution
A negative electrode sheet is developed with a current collector coated with a polyethylene glycol (PEG) active coating, where the molecular weight of PEG is between 150 and 660, ensuring sufficient electrolyte absorption and distribution, thereby improving lithium ion transport kinetics and battery cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If graphite anode with small layer spacing is used, then structural stability is improved, but lithium ion diffusion capability deteriorates
Solution Approach 1:
The patent introduces a three-dimensional porous structure into the graphite anode by incorporating conductive porous carbon materials. This transforms the traditional two-dimensional interlayer diffusion path into a three-dimensional network, providing additional diffusion channels and significantly improving lithium ion transport speed while maintaining the stable graphite base structure.
Solution Approach 2:
The patent utilizes conductive porous carbon materials with controlled pore structures to create interconnected channels within the graphite anode. These porous structures provide spacious intercalation channels and shortcuts for lithium ion diffusion, enhancing ion transport capability without compromising the overall structural stability of the graphite framework.
2Quantity of substance
If thick electrode is used, then capacity is improved, but liquid-phase transport impedance increases
Solution Approach 1:
The patent segments the thick electrode structure by incorporating a three-dimensional porous carbon network that divides the electrode into multiple interconnected pathways. This segmentation creates numerous short diffusion paths throughout the thick electrode, allowing lithium ions to reach active materials more efficiently and reducing the overall liquid-phase transport impedance despite the increased electrode thickness.
Solution Approach 2:
The conductive porous carbon material creates a hierarchical pore structure within the thick electrode, providing both mechanical support and fluid transport channels. The porous structure facilitates electrolyte penetration and maintains liquid-phase transport efficiency throughout the entire thickness of the electrode, enabling high capacity without proportionally increasing transport impedance.
3Quantity of substance
If polyethylene glycol with low molecular weight is used, then electrolyte absorption capability is improved, but distribution uniformity deteriorates
Solution Approach 1:
The patent optimizes the molecular weight parameter of polyethylene glycol to a specific range (200-1000 g/mol) rather than using either extremely low or high values. This parameter optimization balances the competing requirements: low enough molecular weight to ensure good electrolyte absorption capability through sufficient free volume, but high enough to maintain adequate chain entanglement and distribution uniformity within the electrode matrix.
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 use of PEG in the negative electrode sheet enhances electrolyte absorption, reduces liquid-phase transport impedance, and maintains a low DC resistance level, achieving both fast charging and long-term cycle performance in lithium-ion batteries.
Implementation Method 1
the polyethylene glycol in the negative electrode active coating is able to absorb the electrolyte and swell
Implementation Method 2
it is possible to ensure that polyethylene glycol is able to be evenly distributed in the negative electrode active coating
Implementation Method 3
adding polyethylene glycol to the negative electrode sheet may also bring a certain plasticizing effect, thereby improving the flexibility of the negative electrode sheet
Data Source
AI summary
The disclosure provides a negative electrode sheet and a battery using the same. The negative electrode sheet provided in the disclosure includes a current collector and a negative electrode active coating arranged on the surface of the current collector. The negative electrode active coating contains polyethylene glycol, the molecular weight of polyethylene glycol is 150-660, and the proportion of polyethylene glycol in the negative electrode active coating is not less than 0.2% calculated by mass percentage. The polyethylene glycol in the negative electrode active coating is able to absorb the electrolyte and swell, thereby increasing the transport rate of ions in the electrode sheet, reducing the liquid-phase transport impedance of thick electrodes, and improving the kinetic performance. The DCR value of the battery using the negative electrode sheet is reduced, so the battery using the negative electrode sheet has both good fast charging performance and battery cycle performance.