Layered Negative Electrode Structure for Dendrite-Tolerant Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional secondary batteries face challenges in achieving high energy density and cycle performance, particularly due to limitations in capacity balance between the positive and negative electrodes, which can lead to short circuits caused by lithium dendrite formation.
Innovation Solution
The secondary battery design includes a positive electrode plate and a negative electrode plate with a capacity ratio of N/P < 1, featuring a current collector with a first negative electrode active layer, an insulating material layer, and a second negative electrode active layer. This configuration allows excess lithium ions to form metal lithium composites, enhancing energy density while preventing short circuits by depositing lithium dendrites between the insulating layer and the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode capacity is increased to prevent lithium dendrite formation and short circuits, then battery safety is improved, but energy density decreases due to excess lithium ions remaining unused
Solution Approach 1:
The negative electrode active layer is divided into two distinct layers: a first negative electrode active layer in contact with the electrolyte, and a second negative electrode active layer between the insulating material layer and the current collector. This segmentation allows different regions to serve different functions - the first layer accommodates lithium dendrite deposition for safety, while the second layer provides additional capacity for energy density without compromising safety.
Solution Approach 2:
The patent introduces a vertical dimension to the negative electrode structure by stacking multiple active layers at different positions relative to the current collector. Instead of using a single uniform layer, the active material is distributed across multiple layers separated by an insulating material layer, effectively utilizing the thickness dimension to resolve the contradiction between safety and energy density.
2Reliability
If the insulating material layer thickness is increased to prevent short circuits from lithium dendrites, then battery safety is improved, but ion transmission is hindered
Solution Approach 1:
The insulating material layer is positioned specifically between the two negative electrode active layers, providing localized protection against lithium dendrite penetration. The layer has controlled thickness and material properties that provide sufficient insulation while maintaining adequate ion transmission, applying the principle of local quality optimization rather than uniform protection throughout the entire electrode structure.
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
This design achieves high energy density and excellent cycle performance by optimizing the capacity balance and structurally managing lithium dendrite deposition, thereby preventing short circuits and improving safety and performance.
Implementation Method 1
During charging, the lithium ions or sodium ions are deintercalated from the positive electrode and are intercalated into the negative electrode through electrolyte
Implementation Method 2
During discharging, the opposite is true
Implementation Method 3
excess lithium ions to form metal lithium composites
Implementation Method 4
the lithium dendrites are deposited between the insulating material layer and the surface of the current collector
Implementation Method 5
the lithium-philic material in the second negative electrode active layer can be further combined with the lithium dendrites intercalated into the second negative electrode active layer, thereby absorbing the lithium dendrites
Data Source
AI summary
The present application provides a secondary battery (4) and an electrical apparatus. The secondary battery (4) includes a positive electrode plate and a negative electrode plate, the total capacity of the positive electrode plate is P, the total capacity of the negative electrode plate is N, N and P satisfy: N/P<1. The negative electrode plate includes a current collector, and a first negative electrode active layer, an insulating material layer, and a second negative electrode active layer which are arranged on the surface of the current collector in sequence. The secondary battery (4) has high energy density and excellent cycle performance.