Layered Cathode Coating for High-Voltage Low-Cobalt Li-Ion Batteries
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Solution Overview
Problem
The increasing demand for large-sized, high-capacity, and high-energy-density rechargeable lithium batteries poses a challenge due to the limited supply and high cost of cobalt, a rare metal, which is essential for many existing positive electrode active materials.
Innovation Solution
A positive electrode active material is developed, comprising core particles of lithium nickel-manganese-based composite oxide with a first coating layer containing aluminum and a second coating layer containing cobalt, which enhances capacity, reduces production costs, and improves high-voltage and high-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt-containing positive electrode active materials are used to achieve high capacity and high energy density, then battery performance is improved, but production cost increases and resource availability decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode active material by controlling the ratio of nickel to manganese atoms and limiting cobalt content to 0.5-5 atomic percent. This parameter optimization allows achieving high capacity (4.2-4.8 V voltage range) while reducing cobalt dependency and production costs
Solution Approach 2:
The patent creates a composite positive electrode active material comprising nickel, manganese, cobalt, and aluminum atoms arranged in a specific layered structure. This composite approach combines the high capacity benefits of nickel with the stability of manganese, while using minimal cobalt and aluminum as dopants to optimize performance and reduce costs
2Quantity of substance
If high-voltage operating conditions are applied to increase energy density, then battery capacity is improved, but gas generation increases and cycle life decreases
Solution Approach 1:
The patent changes the electrochemical parameters by enabling operation at high voltage (4.2-4.8 V) through material composition optimization. The controlled Ni:Mn ratio and doping with cobalt and aluminum stabilize the crystal structure at high voltage, preventing oxygen release and gas generation that typically occur above 4.35 V
Solution Approach 2:
The patent applies preliminary stabilization measures by doping the positive electrode material with cobalt and aluminum atoms during synthesis. This preliminary action prevents structural degradation and gas generation before high-voltage operation begins, allowing sustained high-voltage charging without harmful side reactions
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 proposed solution achieves high initial charge/discharge capacity and efficiency under high-voltage conditions, ensures long cycle-life characteristics, and effectively suppresses gas generation at high-voltage and high-temperature operations.
Implementation Method 1
performing a first heat treatment to obtain a lithium nickel-manganese-based composite oxide
Implementation Method 2
drying them and performing a second heat treatment
Data Source
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AI summary
Disclosed are a positive electrode active material, a method of preparing the same, and a positive electrode and a rechargeable lithium battery including the same, the positive electrode active material including core particles including a layered lithium nickel-manganese-based composite oxide, a first coating layer on a surface of the core particles and containing Al, and a second coating layer on the first coating layer and containing Co.