Positive Electrode Chelation Layer for Thermal Runaway Resistance
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Solution Overview
Problem
Secondary batteries face challenges in achieving good thermal safety and rate performance due to decomposition of the CEI film on the positive electrode plate, leading to thermal runaway from contact between exposed active sites and the electrolyte.
Innovation Solution
Incorporating chelated particles with an organic compound containing a cyano group into the positive electrode active material layer, which improves structural stability and reduces the probability of contact with the electrolyte, thereby enhancing thermal safety and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CEI film on the positive electrode plate decomposes, then the battery can operate, but thermal runaway occurs due to contact between exposed active sites and electrolyte
Solution Approach 1:
The patent introduces a protective film formed by fluoroethylene carbonate (FEC) as an intermediary layer between the positive electrode active material particles and the electrolyte. This film acts as a mediator that prevents direct contact between exposed active sites and the electrolyte, thereby eliminating the harmful thermal runaway reaction while allowing the battery to operate normally.
Solution Approach 2:
The patent applies preliminary protective action by pre-forming a stable protective film on the positive electrode active material particles before they can react with the electrolyte. The FEC additive预先 forms this protective layer during initial charging cycles, preventing the subsequent decomposition of the CEI film and exposing of active sites that would lead to thermal runaway.
2Reliability
If the positive electrode active material layer structure is stabilized, then thermal safety improves, but rate performance may deteriorate
Solution Approach 1:
The patent applies local quality by creating a protective film with specific local properties on the surface of positive electrode active material particles. The film has different characteristics in different regions: it provides thermal safety protection where active sites are exposed, while maintaining ion transport pathways in other areas to preserve rate performance. The localized application of FEC-derived protective layers ensures that stability is provided only where needed without compromising overall electrode performance.
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 use of chelated particles with a specific ratio and distribution within the positive electrode active material layer improves both thermal safety and rate performance of the secondary battery, reducing the occurrence of thermal runaway and maintaining high energy density.
Implementation Method 1
the chelated particles include an organic compound containing a cyano group. The organic compound containing the cyano group can be combined with exposed active sites in the positive electrode active material particles
Data Source
Figure 1~2
AI summary
A secondary battery includes a positive electrode plate, where the positive electrode plate has a resistance of R Ω, R ranges from 0.5 to 2. The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, where the positive electrode active material layer is arranged on at least one surfase of the positive electrode current collector. The positive electrode active material layer includes positive electrode active material particles and chelated particles, where the chelated particles include an organic compound containing a cyano group. Within at least one region of 5 µm × 5 µm of the positive electrode active material layer, a ratio of a quantity of the chelated particles to a quantity of the positive electrode active material particles ranges from 0.01 to 0.5. The secondary battery provided in this application can have good thermal safety performance and rate performance.