Lithium Battery Coated Cathode for High-Temperature Stability
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Solution Overview
Problem
Lithium rechargeable batteries face challenges in achieving high capacity and stability due to decomposition of electrolyte and active materials at elevated temperatures, which affects safety and cycle-life characteristics.
Innovation Solution
A rechargeable lithium battery design incorporating a positive active material with a core compound and a coating layer, along with a non-aqueous electrolyte containing a specific organic solvent and lithium salt, enhances stability and cycle-life by optimizing the composition and amount of the coating layer and electrolyte additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity positive active materials are used to increase battery capacity, then the discharge voltage and energy density are improved, but the stability and safety deteriorate due to decomposition at elevated temperatures
Solution Approach 1:
The patent uses composite materials by combining a core positive active material (LiCo1-x-yNixMgyO2, LiNi1-x-yCoxMgyO2, or LiNi1-x-yCoxAl yO2) with a coating layer material (Li2SiO3, Li3PO4, Li2SiO2O, or Li4SiO4) to create a composite structure that maintains high capacity while improving thermal stability and safety
Solution Approach 2:
The patent changes the chemical composition parameters of the positive active material by controlling the ratios of Ni, Co, Mn, Al, and other elements (where 0 < x, y < 0.5 and x + y < 1.0), and adjusts the coating layer thickness (0.1-10 μm) to optimize both capacity and stability
2Quantity of substance
If the positive active material is operated at high charge cut-off voltage (4.3V to 4.5V) to increase capacity, then the energy density is improved, but the decomposition of electrolyte and active materials is accelerated
Solution Approach 1:
The patent applies a protective coating layer to the surface of the positive active material particles before battery assembly. This preliminary protective action prevents direct contact between the high-voltage active material and the electrolyte, thereby preventing decomposition even when charged to high voltages of 4.3V to 4.5V
Solution Approach 2:
The coating layer acts as an intermediary barrier between the positive active material and the electrolyte, allowing lithium ion transport while preventing harmful chemical reactions and decomposition at high operating voltages
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 battery exhibits improved stability and cycle-life characteristics, particularly at high temperatures, with extended continuous charging time and maintained discharge capacity over multiple cycles.
Implementation Method 1
a coating layer formed on the core. The coating layer includes a material represented by MxPyOz
Implementation Method 2
a non-aqueous electrolyte including a non-aqueous organic solvent, a lithium salt, and an additive
Implementation Method 3
lithium-transition element composite oxides capable of intercalating lithium such as LiCoO2, LiMn2O4, LiNiO2, and carbonaceous materials, such as artificial and natural graphite, and hard carbon, have been used, which may all intercalate and deintercalate lithium ions
Data Source
AI summary
The rechargeable lithium battery of the present invention includes a positive electrode including a positive active material, a negative electrode including a negative active material, and a non-aqueous electrolyte. The positive active material includes a core and a coating layer formed on the core. The core is made of a material such as LiCo0.98M′0.02O2, and the coating layer is made of a material such as MxPyOz. The electrolyte solution includes a nitrile-based additive. The rechargeable lithium battery of the present invention shows higher cycle-life characteristics and longer continuous charging time at high temperature.