Lithium Battery Electrode Segmentation for Initial Discharge Efficiency
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Solution Overview
Problem
Rechargeable lithium batteries face inefficiencies due to non-reversible capacity issues in carbon-based negative active materials, leading to reduced lifecycle and energy density, particularly exacerbated by thick active material layers and high active mass.
Innovation Solution
The battery design incorporates a positive electrode with coated and uncoated regions, and a negative electrode with a lithium source separated by a predetermined interval from the active region, enhancing initial discharge efficiency and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-based negative active material is used with thick active material layer and high active mass, then the battery capacity increases, but the initial discharge efficiency deteriorates and non-reversible capacity increases
Solution Approach 1:
The negative electrode is segmented into a coating region with negative active material and an uncoated region without negative active material. This segmentation allows the battery to achieve both high capacity (through the coating region with thick active material layer) and high initial discharge efficiency (through the uncoated region that provides reversible capacity), resolving the technical contradiction between quantity of substance and productivity.
2Device complexity
If a carbon-based negative active material is used, then the battery structure is simple, but non-reversible capacity occurs and lifecycle deteriorates
Solution Approach 1:
The negative electrode is divided into a coating region and an uncoated region. The uncoated region provides reversible capacity that compensates for the non-reversible capacity generated in the coating region, thereby improving battery lifecycle while maintaining a relatively simple electrode structure that does not require complex additional components.
3Quantity of substance
If the negative electrode has high active mass and thick active material layer, then the energy density increases, but the discharge efficiency and lifecycle intensify deterioration
Solution Approach 1:
The negative electrode is segmented into a coating region containing the thick active material layer for high energy density and an uncoated region that provides reversible capacity. This segmentation ensures that the high active mass in the coating region contributes to energy density while the uncoated region maintains discharge efficiency and lifecycle, resolving the contradiction between quantity of substance and productivity.
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 configuration improves the initial charge and discharge characteristics, increasing the energy density and capacity of the lithium battery by optimizing the distribution and utilization of active materials.
Implementation Method 1
a lithium source at the negative electrode and separated from an end of the active region by a predetermined interval
Implementation Method 2
a rechargeable lithium battery includes a positive electrode and a negative electrode... an electrolyte
Data Source
AI summary
A rechargeable lithium battery includes a separator between a positive electrode and a negative electrode. The positive electrode has a positive electrode coating region and a positive electrode uncoated region. A positive active material is coated to a positive electrode current collector in the positive electrode coating region, and the positive active material is not coated in the positive electrode uncoated region. The negative electrode includes a negative electrode coating region and a negative uncoated region. A negative active material is coated to a negative electrode current collector in the negative electrode coating region, and the negative active material is not coated and a lithium source is in the negative uncoated region. The negative electrode coating region includes an active region corresponding to the positive electrode coating region. The lithium source is at the negative electrode and separated from an end of the active region by a predetermined interval.