Anode Mixture Layer Tuning for Fast-Charging Lithium-Ion Batteries
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining lifespan during rapid charging due to high current density, which causes overvoltage and lithium metal precipitation, leading to battery deterioration.
Innovation Solution
An anode with a specific anode mixture layer composition and structure, including artificial graphite as the primary active material, a binder with a glass transition temperature between −15° C. and 0° C., and a conductive material, applied at a controlled loading amount and density, with a permeability and current density combination that limits the R value to 3,000 or less, preventing overvoltage and lithium metal deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high current density is used for rapid charging, then charging speed is improved, but overvoltage and lithium metal precipitation occur leading to battery deterioration
Solution Approach 1:
The invention changes the physical parameters of the anode mixture layer by controlling its density (1.60 g/cc to 1.65 g/cc) and permeability (140 sec/100 cc to 150 sec/100 cc) within specific ranges. This optimization of parameters allows the anode to handle high current density during rapid charging while preventing overvoltage and lithium metal precipitation, thus resolving the contradiction between charging speed and battery lifespan
Solution Approach 2:
The invention uses a composite anode mixture layer comprising multiple components including graphite (50-90 wt%), silicon (5-30 wt%), and conductive materials (1-20 wt%). This composite structure combines the advantages of different materials to achieve both high charging rate capability and long cycle life, preventing deterioration under rapid charging conditions
2Speed
If high current density charging is performed, then rapid charging performance is improved, but lithium metal precipitation and electrolyte decomposition occur
Solution Approach 1:
The invention optimizes the density and permeability parameters of the anode mixture layer to specific ranges (density: 1.60-1.65 g/cc, permeability: 140-150 sec/100 cc). These parameter changes enable the anode to accept lithium ions at high rates without causing lithium metal precipitation or electrolyte decomposition, thus achieving rapid charging without harmful side reactions
Solution Approach 2:
The invention employs a porous anode mixture layer structure with controlled permeability (140-150 sec/100 cc). The porous structure facilitates efficient lithium ion transport throughout the electrode, preventing local accumulation of lithium ions that would lead to metal precipitation, while maintaining the structural integrity needed to handle high charging rates
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
This configuration enhances rapid charging performance and extends battery lifespan by allowing higher current charging without premature degradation, ensuring excellent performance under rapid charging conditions.
Implementation Method 1
a technology for developing an anode capable of accepting lithium ions at a faster rate is required
Data Source
AI summary
The present invention relates to a secondary battery comprising a cathode, an anode and a separator interposed between the cathode and the anode, wherein the anode comprises an anode current collector and an anode mixture layer formed on at least one surface of the anode current collector, the anode mixture layer comprises an anode active material, a binder, and a conductive material, a loading amount of the anode mixture layer is 5 mg/cm2 to 15 mg/cm2 and value R of the anode mixture layer is 3,000 or less, wherein R means (permeability of the anode mixture layer)×(current density of a battery)2. According to the present invention, an overvoltage phenomenon of an anode surface and the deposition of lithium metal caused thereby can be prevented so that charging can be performed with a higher current, and thus rapid charging performance is improved, and lifespan is excellent even in the same current.