Iodine-Doped Positive Electrode Material for High-Voltage Stability
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Solution Overview
Problem
Lithium-ion batteries face issues with rapid deterioration and gas production under high temperatures and high voltages due to oxygen release and structural phase transitions in positive electrode materials, leading to poor kinetic performance and temperature rise during large-rate charge/discharge conditions.
Innovation Solution
A positive electrode material with a controlled molar ratio of iodine to nickel (0.25 to 1.5) is introduced, where iodine ion lattice doping forms lithium iodate as a protective layer, enhancing oxidation resistance, reducing interface impedance, and improving electronic conductivity, thereby inhibiting gas production and enhancing cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If deep lithium deintercalation is performed to increase capacity, then energy density is improved, but oxygen release and structural phase transition occur leading to rapid deterioration and gas production
Solution Approach 1:
The patent applies preliminary action by pre-forming a protective coating layer on the positive electrode material surface before battery operation. This coating layer, formed through iodine ion lattice doping during material synthesis, prevents oxygen release and structural phase transition during deep lithium deintercalation, thereby maintaining cycling stability while enabling high capacity utilization.
Solution Approach 2:
The patent uses an intermediary substance (iodine-doped surface layer forming lithium iodate) that mediates between the positive electrode material and the electrolyte. This intermediary layer suppresses side reactions, prevents direct contact between reactive oxygen species and electrolyte, and maintains interface stability during high-voltage operation and deep deintercalation.
2Quantity of substance
If high voltage operation is adopted to increase energy density, then capacity is improved, but interface instability and gas production increase
Solution Approach 1:
The patent converts the harmful effect of high-voltage-induced interface instability into a beneficial protective mechanism. By introducing iodine ion lattice doping, the surface layer transforms into a stable lithium iodate structure that not only resists oxidation but also suppresses gas-generating side reactions, thereby enabling high-voltage operation with reduced gas production.
Solution Approach 2:
The patent changes the chemical composition and electronic structure parameters of the surface layer through iodine doping. This modifies the oxidation resistance and interfacial stability parameters, allowing the material to withstand high voltage operation without generating excessive gas, thus resolving the contradiction between energy density and gas production.
3Quantity of substance
If ternary positive electrode material is used to increase capacity, then energy density is improved, but kinetic performance deteriorates causing temperature rise under large-rate charge/discharge
Solution Approach 1:
The patent applies local quality by creating a surface layer with distinct chemical composition and electronic properties through iodine ion lattice doping. This localized modification improves electron hopping paths and electronic conductivity at the critical surface region where charge transfer occurs, thereby enhancing kinetic performance and reducing temperature rise during large-rate charge/discharge while preserving the high capacity of the bulk ternary material.
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 solution effectively stabilizes the electrode material under high temperatures and high voltages, reducing gas production and temperature rise, and improving the overall performance of lithium-ion batteries by forming a protective lithium iodate layer that enhances oxidation resistance and electronic conductivity.
Implementation Method 1
introducing iodine ion lattice doping into a surface layer of the positive electrode material
Implementation Method 2
With extremely strong oxidation resistance, lithium iodate can serve as an external protective layer
Implementation Method 3
the side reactions on the surface further increase interface impedance
Implementation Method 4
increase electron hopping paths, and enhance the electronic conductivity
Implementation Method 5
oxygen ions on a material surface have high activity, easily causing side reactions with an electrolyte
Data Source
AI summary
A positive electrode material, including a substrate and a first region located on a surface of the substrate, where a molar ratio of iodine element to nickel element in the first region is 0.25 to 1.5. In this application, iodine ion lattice doping is introduced into the surface layer of the positive electrode material, so that the structural stability of the positive electrode material under high temperatures and high voltages and the kinetic performance under large-rate charge/discharge conditions are effectively improved, thereby reducing gas production in high-temperature and high-voltage storage and temperature rise under large-rate charge/discharge conditions of the electrochemical device, and improving the comprehensive performance of the electrochemical device.