Positive Electrode Protective Layer for Battery Short-Circuit Safety
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries are prone to safety incidents such as fires and explosions due to short circuits caused by impacts or punctures, primarily between the positive electrode current collector and the negative electrode active material layer, limiting their extensive application.
Innovation Solution
An electrochemical device with a positive electrode that includes a protective layer between the current collector and the active material layer, where the protective layer's coverage is strategically controlled to isolate conduction and reduce the risk of short circuits, comprising inorganic particles, binders, and conductive agents, ensuring adequate protection and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is added between the current collector and active material layer, then safety performance is improved by suppressing short circuits, but device complexity increases
Solution Approach 1:
A protective layer comprising inorganic particles and binder is introduced as an intermediary between the current collector and the positive electrode active material layer. This protective layer acts as a mediator that prevents direct contact and potential short circuits between the current collector and active material, while still allowing lithium ion transport. The protective layer specifically addresses the safety issue by isolating the current collector from the active material layer, thereby resolving the contradiction between improved safety and increased device complexity.
2Reliability
If the protective layer coverage area is increased, then safety performance is improved by better isolation, but manufacturing precision requirements increase
Solution Approach 1:
The protective layer is selectively applied to specific regions of the current collector rather than uniformly across the entire surface. Specifically, the protective layer is applied to the first surface of the current collector where it contacts the positive electrode active material layer, with controlled coverage ratios. This local application approach ensures that safety-critical areas are protected while avoiding unnecessary complexity in manufacturing precision requirements for the entire device.
3Reliability
If the protective layer completely covers the current collector surface, then safety performance is maximized, but electrochemical performance deteriorates due to excessive resistance
Solution Approach 1:
Instead of completely covering the current collector surface with the protective layer, the invention applies the protective layer with a controlled coverage ratio. The protective layer covers a specific portion of the current collector surface (with the coverage ratio falling within a specified range), which is sufficient to prevent short circuits and improve safety performance, while leaving other areas uncovered to maintain good electrochemical performance and minimize resistance. This partial coverage approach resolves the contradiction between maximizing safety and maintaining electrochemical performance.
Data Source
AI summary
An electrochemical device, including a positive electrode, where the positive electrode includes a positive electrode current collector, a first protective layer, and a first positive electrode active material layer. The positive electrode current collector includes a first surface and a second surface opposite to each other, and the first protective layer is disposed between the first surface and the first positive electrode active material layer. The first surface includes a first region and a second region, where the first region is provided with the first positive electrode active material layer, and the second region is not provided with the first positive electrode active material layer. An area of the first region is A1 cm2, an area of the second region is A2 cm2, and an area of the first protective layer is A3 cm2, satisfying: 0.5≤A3/(A1+A2)≤1. The electrochemical device of this application has significantly improved safety performance.