LiCoO2 Battery High-Voltage Stability via Doping and Additive
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Solution Overview
Problem
Lithium-ion batteries using LiCoO2 as a positive active material face instability and rapid capacity decrease when operated at high voltages greater than 4.2 V due to lattice deformation, gas production, and corrosion, leading to poor performance and short cycle life.
Innovation Solution
A lithium-ion battery design incorporating a metal ion-doped lithium cobalt oxide material (Lix1Coy1M1-y1O2-z1Qz1) with a polynitrile six-membered nitrogen-heterocyclic compound additive in the electrolyte, which forms a stable complex layer on the positive active material to reduce lattice deformation and surface activity, thereby enhancing structural stability and cycle performance under high-voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiCoO2 is used as positive active material and voltage is increased above 4.2V to extract more lithium ions, then capacity is improved, but structural stability deteriorates due to lattice deformation and Co4+ formation
Solution Approach 1:
The patent applies parameter changes by modifying the voltage window and chemical composition parameters. Specifically, it uses LiCoO2 with controlled lithium content (x=0.5-1.0) and operates within a voltage range of 3.0-4.35V, avoiding the unstable region above 4.2V while still achieving high capacity through optimized electrochemical parameters rather than pushing into the unstable high-voltage regime
Solution Approach 2:
The patent employs composite material strategy by combining LiCoO2 positive electrode with specific electrolyte formulations containing LiPF6 (0.5-2.0M) and cyclic carbonate solvents. This composite system creates a stable interface that prevents lattice degradation while enabling high lithium ion extraction, effectively coupling the high-capacity material with a protective electrolyte environment
2Quantity of substance
If deep delithiation is performed to increase capacity, then more lithium ions are extracted, but gas production increases due to electrolyte oxidation and HF corrosion
Solution Approach 1:
The patent creates an inert chemical environment by using highly pure LiCoO2 material with controlled synthesis conditions that minimize surface defects and impurities. The electrolyte formulation with precise LiPF6 concentration (0.5-2.0M) and purified cyclic carbonate solvents creates a chemically inert atmosphere that resists decomposition even during deep delithiation, preventing gas-generating side reactions
Solution Approach 2:
The patent controls the concentration parameter of LiPF6 within 0.5-2.0M range and operates within a voltage window of 3.0-4.35V, which optimizes the balance between lithium ion extraction capacity and electrolyte stability. This parameter optimization prevents excessive electrolyte oxidation and HF generation that would otherwise occur at higher voltages or concentrations
3Quantity of substance
If high voltage operation is used to increase capacity, then energy density is improved, but cycle life decreases due to rapid capacity decrease
Solution Approach 1:
The patent optimizes the voltage parameter window to 3.0-4.35V, which is high enough to enable substantial lithium ion extraction (x=0.5-1.0) for high capacity, but constrained below the 4.35V threshold that would cause rapid degradation. This parameter optimization achieves high energy density while maintaining long cycle life by avoiding the most damaging voltage region
Solution Approach 2:
The patent uses a composite system of high-purity LiCoO2 with optimized electrolyte composition (LiPF6 0.5-2.0M in cyclic carbonates). This composite material system provides both high lithium ion extraction capability and long-term structural stability, enabling the battery to maintain high capacity over extended cycling by protecting the LiCoO2 lattice from progressive degradation
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 significantly improves cycle and storage performance by reducing gas production, side reactions, and lattice instability, leading to enhanced capacity retention and reduced thickness expansion at high temperatures and voltages.
Implementation Method 1
the electrolyte contains an additive A that is selected from one or more of compounds represented by Formula I-1, Formula 1-2, and Formula 1-3... forms a stable complex layer on the positive active material
Implementation Method 2
A positive active material of the positive electrode plate includes Lix1Coy1M1-y1O2-z1Qz1, where M is selected from one or more of Al, Ti, Zr, Y, and Mg... reduces lattice deformation
Data Source
AI summary
This application provides a lithium-ion battery and an apparatus. The lithium-ion battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. A positive active material of the positive electrode plate includes Lix1Coy1M1-y1O2-z1Qz1, where 0.5≤x1≤1.2, 0.8≤y1≤1.0, 0≤z1≤0.1, M is selected from one or more of Al, Ti, Zr, Y, and Mg, and Q is selected from one or more of F, Cl, and S. The electrolyte contains an additive A that is a polynitrile six-membered nitrogen-heterocyclic compound with a relatively low oxidation potential. The lithium-ion battery has superb cycle performance and storage performance, especially under high-temperature and high-voltage conditions.