Mixed LiCoO2 Zr Mg Mo Positive Electrode Battery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte secondary batteries with lithium transition metal complex oxides as positive active materials face deterioration and capacity reduction when the end of charge voltage is raised, due to decomposition of the electrolyte solution and destruction of the crystal structure, leading to poor charge-discharge cycle characteristics and thermal stability.
Innovation Solution
A nonaqueous electrolyte secondary battery design that mixes lithium transition metal complex oxide A, containing Zr and Mg, with lithium transition metal complex oxide B, containing Mn, Ni, and Mo, as the positive active material, to enhance charge-discharge capacity and stability by inhibiting electrolyte decomposition and crystal structure destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the end of charge voltage is raised to improve capacity and energy density, then the capacity coefficient of the positive electrode is improved, but the deterioration of the battery due to charge-discharge cycles becomes more remarkable
Solution Approach 1:
The patent uses a composite positive active material consisting of LiCoO2 containing both Zr and Mg dopants. The combination of multiple dopant elements creates a composite structure that simultaneously achieves high capacity utilization and good cycle stability. This composite approach allows the material to maintain structural integrity at high voltages while enabling deeper charge capacity.
Solution Approach 2:
The patent applies local quality modification by specifically doping LiCoO2 with Zr and Mg elements at controlled concentrations (0.01-0.1 mol each). The dopants are incorporated into specific crystallographic sites of the LiCoO2 structure, creating localized regions with enhanced stability and electrochemical performance. This local modification allows the material to exhibit improved cycle characteristics at high voltage without sacrificing overall capacity.
2Quantity of substance
If the end of charge voltage is raised to enhance capacity, then the energy density is improved, but the decomposition of the electrolyte solution at the surface of the positive electrode becomes apt to occur
Solution Approach 1:
The patent changes the chemical composition parameters of the positive active material by introducing Zr and Mg dopants into LiCoO2. This parameter modification alters the electrochemical window and surface properties of the material, enabling it to operate stably at higher voltages (4.3-4.4V) without causing electrolyte decomposition. The dopant concentration is precisely controlled to optimize this effect.
Solution Approach 2:
The Zr and Mg dopants act as intermediaries between the LiCoO2 host structure and the electrolyte. These dopant elements modify the surface chemistry and electronic structure, creating a more stable interface that prevents direct harmful interactions between the high-voltage positive electrode and the electrolyte solution, thereby suppressing decomposition reactions.
3Quantity of substance
If the end of charge voltage is raised to deepen the depth of charge capacity, then the capacity is enhanced, but the deterioration of the structure of the positive active material becomes apt to occur
Solution Approach 1:
The patent modifies the compositional parameters of LiCoO2 by incorporating Zr and Mg elements in specific proportions. This composition change stabilizes the crystal structure at high oxidation states, allowing the material to accommodate deeper charge capacities without structural collapse. The dopants reinforce the lattice structure and prevent Jahn-Teller distortion.
Solution Approach 2:
The Zr and Mg dopants are incorporated into the LiCoO2 structure during the synthesis process, performing a preliminary stabilization of the crystal lattice before the battery undergoes charge-discharge cycling. This pre-conditioning of the structure prevents deterioration during subsequent high-voltage operation, enabling sustained deep charge capacity over many cycles.
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 achieves improved charge-discharge cycle characteristics and thermal stability, allowing for a higher end of charge voltage without capacity loss, with Mo in the complex oxide B preventing Mn elution and maintaining battery integrity.
Implementation Method 1
Mo in the complex oxide B preventing Mn elution and maintaining battery integrity
Implementation Method 2
decomposition of an electrolyte solution at the surface of the positive electrode
Implementation Method 3
a carbon material capable of occluding/releasing lithium ions is used as a negative active material
Data Source
AI summary
A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive active material, a negative electrode containing a negative active material and a nonaqueous electrolyte, wherein a lithium transition metal complex oxide A formed by allowing LiCoO2 to contain at least both of Zr and Mg and a lithium transition metal complex oxide B having a layered structure and containing at least both of Mn and Ni as transition metals and containing molybdenum (Mo) are mixed and used as said positive active material.