Negative Electrode End-Region Doping to Suppress Lithium Precipitation
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Solution Overview
Problem
The precipitation of lithium from the negative electrode in power storage devices can cause various problems, and if the edge of the negative electrode is not pre-doped, the effects of pre-doping are not sufficiently obtained, leading to degraded characteristics of the power storage device.
Innovation Solution
A power storage device comprising an electrode assembly with a negative electrode doped with lithium, where the negative electrode has a specific structure with surplus, end, and center regions, and the negative electrode potential of these regions satisfy certain formulas to inhibit lithium precipitation and enhance device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pre-doping is performed only at the center region of the negative electrode, then the manufacturing process is simplified, but lithium precipitation occurs at the edge region causing degraded device characteristics
Solution Approach 1:
The patent applies local quality by creating different doping concentrations in different regions of the negative electrode. The center region has a first doping concentration while the edge region has a second doping concentration that is higher than the first. This localized variation in doping quality prevents lithium precipitation at the edge while maintaining manufacturing feasibility through a controlled gradient structure.
Solution Approach 2:
The patent implements preliminary action by performing pre-doping treatment before the electrode is assembled into the power storage device. The negative electrode is doped with lithium in advance, creating a doping concentration distribution that prepares the electrode to prevent lithium precipitation during subsequent charging cycles. This preliminary doping action addresses the reliability issue before the device operates.
2Reliability
If pre-doping is performed at the edge region of the negative electrode, then lithium precipitation is prevented, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the doping concentration parameter across different regions of the negative electrode. The center region has a first doping concentration and the edge region has a second doping concentration that is higher. This parameter variation is achieved through controlled pre-doping processes that create a gradient distribution, preventing lithium precipitation while managing manufacturing complexity through systematic parameter control.
3Object-affected harmful factors
If the negative electrode potential at the edge region is too low, then lithium precipitation is inhibited, but the energy density of the device decreases
Solution Approach 1:
The patent applies local quality by establishing different potential conditions in different regions of the negative electrode. The edge region is designed to have a lower potential (VA ≤ 2.0 V) to prevent lithium precipitation, while the center region can operate at higher potentials (VC > 1.0 V) to maintain energy density. This localized potential differentiation allows the device to achieve both lithium precipitation prevention and acceptable energy density through region-specific optimization.
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 proposed solution effectively inhibits the precipitation of lithium from the negative electrode, resulting in a power storage device with excellent characteristics, including improved cycle durability and energy density.
Implementation Method 1
a process of doping an electrode active material with alkali metal in advance has been adopted for various purposes. The process of doping the electrode active material with alkali metal in advance is referred to as pre-doping
Implementation Method 2
lithium is easily precipitated from the edge of the negative electrode
Data Source
AI summary
A power storage device may include an electrode assembly including a positive electrode, a separator, and a negative electrode, and an electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. The active material layer comprises a surplus region A not facing the positive electrode active material layer, an end region B facing a region in the positive electrode active material layer, the region extending from an end of the positive electrode active material layer toward a center of the positive electrode active material layer by a length of 5% of a length from the center to the end, and a center region C. A negative electrode potential VA and a negative electrode potential VC after the positive electrode and the negative electrode are short-circuited satisfy: (1) VA≤2.0 V; (2) VC≤1.0 V; and (3) VA/VC≥0.7.