Lithium Ion Battery Insulating Layer Heat Suppression
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Solution Overview
Problem
Lithium ion batteries, especially those used in high-output applications, generate excessive heat during charge and discharge, posing safety concerns due to uncoated sections of the positive electrode collector being prone to oxidation and exothermic reactions.
Innovation Solution
A lithium ion battery design featuring a positive electrode with a positive electrode active material layer and an insulating layer containing trilithium phosphate (LPO) and an inorganic filler, where the insulating layer is strategically placed adjacent to the positive electrode active material layer to suppress heat generation by forming a coating film on the negative electrode, thereby reducing exothermic reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the positive electrode collector has uncoated sections for current collection, then electrical conductivity and current collection efficiency are improved, but the uncoated sections become prone to oxidation and exothermic reactions, generating heat and reducing safety
Solution Approach 1:
The insulating layer is applied locally only to specific regions of the positive electrode collector where it is needed for protection, while leaving other regions uncovered for current collection. This localized application allows the collector to maintain its electrical conductivity function in uncovered areas while providing oxidation protection in covered areas, thus resolving the contradiction between current collection efficiency and heat generation prevention.
Solution Approach 2:
An insulating layer comprising a porous layer and a non-porous layer is introduced as an intermediary between the positive electrode collector and the environment. This intermediate layer prevents direct contact between the collector surface and oxidizing substances, thereby eliminating the harmful oxidation reactions and heat generation while allowing the underlying collector to continue its current collection function.
2Object-affected harmful factors
If an insulating layer is added to cover the positive electrode collector, then heat generation from oxidation is suppressed, but the device complexity and manufacturing cost increase
Solution Approach 1:
The insulating layer is divided into two distinct sub-layers: a porous layer and a non-porous layer. Each layer performs a specific function - the porous layer provides initial protection and the non-porous layer provides enhanced barrier properties. This segmentation allows for optimized performance of each layer while maintaining overall simplicity of the structure, avoiding the need for a single complex thick layer.
Solution Approach 2:
The insulating layer is constructed as a composite structure combining porous and non-porous materials. This composite approach leverages the advantages of both material types - the porous structure for surface area and initial protection, and the non-porous structure for dense barrier properties - thereby achieving effective heat generation suppression with a relatively simple and manufacturable design.
3Reliability
If LPO is added to the positive electrode active material layer, then overcharge resistance is enhanced through coating film formation on the negative electrode, but the manufacturing precision and control of coating thickness become more difficult
Solution Approach 1:
LPO is pre-added to the positive electrode active material layer during the electrode manufacturing process, before battery assembly. This preliminary incorporation ensures that LPO is uniformly distributed in the positive electrode structure, and during subsequent charging cycles, LPO gradually leaches out to form the protective coating film on the negative electrode. This approach provides better control over coating formation compared to adding LPO later, as it allows for controlled, gradual release of LPO ions.
Solution Approach 2:
The LPO incorporated in the positive electrode serves a dual function: it acts as a structural component of the positive electrode itself, and simultaneously serves as a source material for forming the protective coating film on the negative electrode through controlled leaching during charging. This self-service mechanism eliminates the need for separate coating processes, thereby maintaining manufacturing simplicity while achieving the desired coating thickness control.
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 solution effectively suppresses heat generation and enhances overcharge resistance, leading to a safer battery with reduced weight and cost, suitable for high-rate charge/discharge cycles and applications requiring high safety, such as in vehicles.
Implementation Method 1
LPO undergoes an acid-base reaction with such an acid, and the resulting phosphate ions (PO43−) leach out
Implementation Method 2
acids are generated as a result of oxidative decomposition of electrolyte solutions when the potential of the positive electrode is high
Implementation Method 3
The phosphate ions have the function of enhancing for instance the overcharge resistance of the battery by reaching the negative electrode and forming a coating film
Data Source
AI summary
An object of this disclosure is to provide a lithium ion battery in which generation of heat can be suitably suppressed. Provided is a lithium ion battery including a positive electrode and a negative electrode. The positive electrode includes a positive electrode collector, a positive electrode active material layer, and an insulating layer provided on another part of the surface of the positive electrode collector, so as to be adjacent to the positive electrode active material layer. The insulating layer contains an inorganic filler and a binder. At least part of the surface of the inorganic filler is covered with LPO.