Lithium-Ion Electrode Orientation Matching for Fast-Charging Safety
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high charging capability and long cycle life during fast charging due to issues with lithium dendrite growth, which can lead to safety hazards and reduced capacity, as existing methods to enhance charging speed often compromise energy density and safety performance.
Innovation Solution
A lithium-ion battery design that optimally matches the orientation index (OI) values of the positive and negative films, within a specific range, to ensure balanced dynamics performance, using a positive active material with a chemical formula Li a Ni x Co y M 1-x-y O 2 and graphite as the negative active material, along with controlled pressing densities and potential doping or coating modifications to improve particle integrity and electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast charging is performed on a lithium-ion battery without fast charging capability, then charging speed is improved, but lithium dendrites are easily grown on the surface of the negative electrode plate, causing capacity loss and safety hazards
Solution Approach 1:
The patent optimizes the orientation index (OI) values of both positive and negative films to specific ranges (0.05≤OIc≤5 and 0.1≤OIa≤3) to change the crystallographic orientation parameters of the active materials. This parameter optimization enables the battery to safely accept fast charging by improving lithium ion transmission speed and preventing dendrite formation, thus resolving the contradiction between charging speed and safety performance
Solution Approach 2:
The patent performs preliminary optimization of the OI values during the battery manufacturing process, preparing the electrode films with optimal crystallographic orientations before fast charging operation. This preliminary preparation ensures that the battery structure is pre-configured to handle fast charging conditions, preventing dendrite growth before it can occur during operation
2Productivity
If coating weight is reduced and conductive agent amount is increased to achieve large charging speed, then charging capability is improved, but energy density of the lithium-ion battery is significantly decreased
Solution Approach 1:
The patent changes the crystallographic orientation parameters (OI values) of the active materials in both electrodes, which fundamentally alters the lithium ion transmission characteristics. This enables fast charging capability to be achieved through structural optimization rather than by increasing conductive agent content or reducing coating weight, thus avoiding the energy density penalty associated with conventional approaches
3Speed
If lithium dendrites continue to grow during use, then charging capability is temporarily enhanced, but the lithium dendrite may puncture the separator, bringing safety hazards
Solution Approach 1:
The patent applies preliminary anti-action by optimizing the OI values of the electrode films to create a battery structure that resists dendrite formation from the outset. The optimized crystallographic orientation of the active materials creates a more uniform lithium ion flux distribution, which counteracts the tendency toward dendrite formation before it can develop, thus preventing the harmful effect while maintaining charging capability
Solution Approach 2:
The patent converts the potential harm of rapid lithium ion insertion (which can cause dendrites) into a benefit by optimizing the film orientations. The optimized structure channels the rapid lithium ion flux into uniform intercalation pathways, transforming what would be a harmful concentrated current into a beneficial uniform distribution that enhances charging speed without dendrite formation
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 optimized OI value ratio between the positive and negative films enhances lithium ion transmission speed, leading to higher charging capability and excellent safety performance during long-term fast charging, while maintaining energy density and cycle life.
Implementation Method 1
The positive active material comprises a material with a chemical formula of Li a Ni x Co y M 1-x-y O 2
Implementation Method 2
the lithium-ion battery comprises a positive electrode plate, a negative electrode plate, a separator and an electrolyte
Data Source
AI summary
The present invention provides a lithium-ion battery, and the lithium-ion battery comprises a positive electrode plate, a negative electrode plate, a separator and an electrolyte. The positive active material comprises a material with a chemical formula of LiaNixCoyM1-x-yO2, the negative active material comprises graphite, the OI value of the positive film represented by OIc and the OI value of the negative film represented by OIa satisfy a relationship: 0.05≤OIa/OIc≤10. By reasonably matching the OI value of the positive film represented by OIc and the OI value of the negative film represented by OIa and making OIa/OIc between 0.05 and 10, the dynamics performance of the positive electrode plate and the dynamics performance of the negative electrode plate can achieve an optimal match, the lithium-ion battery can have higher charging capability, and also have excellent cycle life and excellent safety performance during the long-term fast charging use.