Lithium Battery Electrode Insulating Overlap for Short-Circuit Resistance

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Solution Overview

Problem

Lithium secondary batteries face challenges with insulation between electrodes and cohesive strength between the active material layer and insulating layer, leading to potential short circuits and reduced battery stability due to the limitations of conventional separators and uneven coating of polymer electrolytes.

Innovation Solution

An electrode design for lithium secondary batteries featuring an electrode current collector with an electrode active material layer and an insulating layer that overlap partially, where the thickness ratio of the insulating layer to the active material layer is controlled between 0.02 and 0.4, enhancing insulation and cohesive strength, and a method of simultaneous drying of both layers to improve processability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional separator is used between electrodes, then the battery structure is simple, but the thermal resistance is insufficient leading to short circuit expansion under abnormal conditions

Engineering Contradiction:

Improvethermal resistanceVSAvoidseparator structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies composite materials by combining the conventional polyolefin separator with an insulating layer containing inorganic particles (such as alumina, silica, or boehmite) dispersed in a polymer matrix. This composite structure provides both the shutdown function of the conventional separator and the thermal stability of the insulating layer, preventing short circuit expansion even when the separator shrinks at high temperatures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent segments the separator structure into two functional layers: a conventional polyolefin separator layer that provides shutdown function at low temperatures, and an insulating layer with inorganic particles that provides thermal stability at high temperatures. This segmentation allows each layer to perform its specific function optimally without interfering with the other.

Inventive Principle:

Principle #1Segmentation

2Reliability

If polymer electrolyte is coated on electrode edges, then insulation is improved, but non-uniform coating causes minute internal short circuits

Engineering Contradiction:

ImproveinsulationVSAvoidcoating uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses an insulating layer as an intermediary substance applied to the electrode edges instead of relying on polymer electrolyte coating. This insulating layer provides consistent insulation properties regardless of coating uniformity, eliminating the problem of minute internal short circuits caused by non-uniform polymer electrolyte application while maintaining effective insulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If electrode edges are stacked with perfect overlap, then space utilization is maximized, but short circuit between electrodes may occur

Engineering Contradiction:

Improvespace utilizationVSAvoidshort circuit prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-coating the electrode edges with an insulating layer before stacking. This pre-applied insulation ensures that even when electrodes are perfectly overlapped to maximize space utilization, the insulating layer prevents short circuits between adjacent electrodes, eliminating the need for imperfect stacking alignment.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If insulation tape is wound multiple times to prevent unwinding, then insulation is improved, but the process becomes complicated and thickness increases

Engineering Contradiction:

ImproveinsulationVSAvoidtaping process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical taping system with a coated insulating layer system. Instead of winding insulation tape multiple times around the electrode assembly, the insulating layer is applied directly to the electrode edges during manufacturing. This substitution eliminates the complex winding process, reduces the number of layers needed, and maintains effective insulation without increasing overall thickness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12057566B2Electrode for lithium secondary battery, method of preparing the same and lithium secondary battery including the same

Publication Date: 2024.08.06 LG ENERGY SOLUTION LTD

AI summary

The present invention provides an electrode for a lithium secondary battery, the electrode including an electrode current collector, an electrode active material layer formed on the electrode current collector, and an insulating layer formed on the electrode current collector and overlapping the electrode active material layer in a partial region. Here, a thickness of the electrode active material layer in the region in which the electrode active material layer and insulating layer do not overlap is d1, a thickness of the insulating layer in the region in which the electrode active material layer and insulating layer do not overlap is d2, and d2/d1 is 0.02 to 0.4.