Dual Carbon-Coated Phosphate Cathode for Longer Battery Cycle Life
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Solution Overview
Problem
Existing batteries face challenges in achieving a longer cycle life, particularly in energy storage applications, where the cycle life requirements are increasing.
Innovation Solution
A positive electrode active material with a lithium-containing phosphate coated by a dual carbon coating layer, comprising a pyrolytic carbon layer and a chemical vapor deposition carbon layer, is developed, which balances electronic conductivity and capacity release, allowing for a capacity slow-releasing effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the charge capacity per gram at 25°C is increased to achieve high initial capacity, then the initial capacity is improved, but the cycle life deteriorates due to rapid capacity release
Solution Approach 1:
The patent applies parameter changes by controlling the charge capacity ratio C2/C1 (where C1 is charge capacity at 25°C and C2 is charge capacity at 60°C) to be within 1.015-1.050. This parameter control ensures that the positive electrode active material releases capacity gradually during battery cycles rather than all at once, thereby extending cycle life while maintaining acceptable initial capacity. The specific parameter range balances the contradiction between initial capacity and cycle life.
Solution Approach 2:
The patent employs composite materials by combining the lithium-containing phosphate active material with a dual-layer carbon coating structure. The carbon coating layers with controlled thickness (0.5-5.0 μm total) create a composite structure that moderates capacity release. This composite approach allows the battery to achieve both high initial capacity and extended cycle life by controlling the interaction between the active material and electrolyte through the carbon barrier.
2Reliability
If a carbon coating layer is applied to improve electronic conductivity, then electronic conductivity is improved, but specific surface area increases leading to worse processing performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the carbon coating layers (first layer: 0.3-2.0 μm, second layer: 0.2-3.0 μm) and their weight percentages (first layer: 0.3-2.0%, second layer: 0.2-3.0% based on total positive electrode active material weight). This parameter optimization ensures sufficient electronic conductivity enhancement while limiting specific surface area increase to maintain good processing performance of positive electrode slurry and plates.
3Reliability
If the weight content of carbon coating layers is increased to improve electronic conductivity, then electronic conductivity is improved, but initial capacity is reduced due to excessive capacity hiding
Solution Approach 1:
The patent applies parameter changes by optimizing the weight percentages of carbon coating layers (first layer: 0.3-2.0%, second layer: 0.2-3.0% based on total positive electrode active material weight) and their thickness ratios. This parameter optimization ensures sufficient electronic conductivity enhancement while limiting capacity hiding to maintain acceptable initial capacity. The balanced parameter range resolves the contradiction between conductivity improvement and capacity retention.
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 dual carbon-coated lithium-containing phosphate active material enhances battery cycle life, maintains high initial capacity, and improves power performance and energy conversion efficiency.
Implementation Method 1
comprising a pyrolytic carbon layer and a chemical vapor deposition carbon layer
Implementation Method 2
a chemical vapor deposition carbon layer
Data Source
AI summary
The present application discloses a positive electrode active material, a preparation method thereof, a battery cell, and a power consuming apparatus. The positive electrode active material includes a lithium-containing phosphate, a charge capacity per gram of the positive electrode active material at 25° C. is denoted as C1, the charge capacity per gram of the positive electrode active material at 60° C. is denoted as C2, both units are mAh/g, and C2/C1≥1.020. The positive electrode active material provided in the present application can improve a cycle performance of a battery.