Lithium Battery Negative Electrode with Expandable Binder Pores
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving improved fast-charge characteristics and cycle-life characteristics due to limitations in the design and composition of their negative electrodes.
Innovation Solution
A negative electrode for rechargeable lithium batteries is designed with a current collector and a negative electrode active material layer divided into two regions: a first region in contact with the current collector and a second region containing an expandable binder. This configuration enhances lithium ion insertion and improves the battery's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode structure is used, then the battery structure is simple, but the fast-charge characteristics and cycle-life characteristics are poor
Solution Approach 1:
The negative electrode active material layer is divided into two distinct regions: a first region in direct contact with the current collector and a second region containing the expandable binder. This segmentation allows each region to perform its specific function - the first region provides structural stability while the second region creates pores for lithium ion insertion, thereby improving fast-charge characteristics without requiring complete restructuring of the entire electrode
Solution Approach 2:
The expandable binder is selectively placed in the second region rather than being uniformly distributed throughout the entire active material layer. This local quality approach ensures that the pore-forming function is concentrated where it is most needed for fast charging, while the first region maintains its integrity for stable cycling. The binder content in the second region is specifically controlled to be 1-10 parts by weight per 100 parts by weight of negative electrode active material
2Quantity of substance
If the negative electrode active material layer is made denser to improve capacity, then the capacity increases, but lithium ion insertion becomes difficult
Solution Approach 1:
The expandable binder in the second region creates a porous structure within the negative electrode active material layer. These pores serve as channels and storage spaces for lithium ions, enabling faster ion transport and insertion kinetics. The porosity is achieved through the controlled decomposition and expansion of the binder during battery assembly and initial charging cycles, providing a three-dimensional network that facilitates rapid lithium ion diffusion throughout the electrode
Solution Approach 2:
The negative electrode combines the negative electrode active material with the expandable binder to form a composite structure. This composite material integrates the high capacity characteristics of the active material with the pore-forming capabilities of the binder, achieving a synergistic effect where both density and ion accessibility are optimized simultaneously
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 an expandable binder in the negative electrode active material layer improves the battery's fast-charge characteristics and cycle-life characteristics by creating spaces or pores that facilitate lithium ion insertion, leading to enhanced performance and capacity retention.
Implementation Method 1
the binder which expands in volume upon contact with the electrolyte
Implementation Method 2
a negative electrode and a positive electrode each including an active material capable of intercalating and deintercalating lithium ions
Implementation Method 3
Electrical energy is produced by oxidation and reduction reactions when lithium ions are intercalated/deintercalated at the positive and negative electrodes
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Example embodiments include a negative electrode for a rechargeable lithium battery, a method of preparing the negative electrode, and a rechargeable lithium battery including the negative electrode. The negative electrode for the rechargeable lithium battery includes a current collector and a negative electrode active material layer on the current collector, wherein the negative electrode active material layer includes a first region in contact with the current collector and a second region on the first region. The first region includes a negative electrode active material, and the second region includes an expandable binder and a negative electrode active material.