Tin-Doped Lithium Cobaltate Precursor for High-Voltage Conductivity
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Solution Overview
Problem
Lithium cobaltate-based lithium-ion battery positive electrodes face challenges in maintaining structural stability and conductivity due to the deep de-intercalation of lithium ions at high voltages, leading to capacity decay and reduced cycle performance, especially when doped with common elements like Al, Mg, Cr, and Ni, which result in high interfacial resistance and poor electronic and ionic conductivities.
Innovation Solution
A preparation method involving the use of a tin-based lithium cobaltate precursor, where cobalt salt, precipitant, and complexing agent react to form a precipitate, followed by calcination and ball-milling with dioxane under pressurization, enhancing conductivity and structural stability by forming grain boundary channels for charge migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If lithium cobaltate is doped with common elements (Al, Mg, Cr, Ni) to stabilize structure at high voltage, then structural stability is improved, but electronic and ionic conductivity deteriorates due to dense oxide structure and poor conductivity of dopants
Solution Approach 1:
The patent changes the chemical composition parameter by using tin (Sn) as dopant instead of traditional oxides, and controls the doping concentration at 0.01-0.1 mol/L to optimize both structural stability and conductivity. The tin doping modifies the electronic structure without forming insulating oxide layers, thereby improving conductivity while maintaining stability.
Solution Approach 2:
The patent creates a composite doped lithium cobaltate material where tin atoms are incorporated into the LiCoO2 crystal lattice. This composite structure combines the stability of the lithium cobaltate framework with the beneficial electronic properties of tin doping, achieving both structural stability and improved conductivity simultaneously.
2Quantity of substance
If charge-cut-off voltage is increased to release more lithium ions and obtain larger capacity, then capacity is improved, but structural stability deteriorates due to internal structure collapse and irreversible phase transition
Solution Approach 1:
The patent applies preliminary doping action before the charge-discharge cycles begin. By pre-doping tin into the lithium cobaltate structure, the material is prepared in advance to withstand the structural stresses of high-voltage operation, preventing collapse and phase transitions during subsequent cycling at elevated voltages.
Solution Approach 2:
The tin doping acts as a structural cushioning mechanism that absorbs and distributes the mechanical stress generated during deep lithium de-intercalation at high voltages. This beforehand cushioning prevents the catastrophic structural collapse that would otherwise occur, enabling safe operation at higher capacities.
3Stability of the object's composition
If doping concentration is increased to improve structural stability, then stability is improved, but interfacial resistance increases and rate performance is reduced
Solution Approach 1:
The patent optimizes the doping concentration parameter to a specific range (0.01-0.1 mol/L) that balances structural stability and rate performance. This precise parameter control ensures sufficient tin atoms are present to stabilize the structure while maintaining adequate lithium ion diffusion pathways and electronic conductivity for high rate performance.
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 method significantly improves the conductivity and cycle performance of lithium cobaltate, enabling better charge migration and retaining capacity over multiple cycles, as evidenced by higher conductivity and capacity retention ratios compared to undoped materials.
Implementation Method 1
adding a cobalt salt solution, a precipitant and a complexing agent concurrently for reaction, and after the reaction is completed, performing solid-liquid separation to obtain a precipitate
Implementation Method 2
first calcining the precipitate in an inert atmosphere, and then calcining the precipitate in an oxidizing atmosphere to obtain a calcined material
Implementation Method 3
subjecting the ball-milled product to a heating and pressurization treatment to obtain the tin-based lithium cobaltate precursor
Data Source
AI summary
The present disclosure discloses a preparation method of a tin-based lithium cobaltate precursor and use thereof. The method involves adding a cobalt salt solution, a precipitant and a complexing agent for reaction to obtain a precipitate, wherein the precipitant is a mixed solution of carbonate and stannate; calcining the precipitate; and mixing the calcined material with dioxane, ball-milling the mixture, and subjecting the ball-milled product to a heating and pressurization treatment to obtain the tin-based lithium cobaltate precursor. In the present disclosure, after carbonate and stannate are blended, the blend react with cobalt salt to form the co-precipitate of cobalt carbonate and cobalt stannate, and after calcination, a mixture of cobalt(II,III) oxide and tin dioxide is formed. By utilizing dioxane for solvent hot pressing, particles are bonded to each other, forming grain boundary channels. In addition, by doping with tin, the conductivity of the material is improved.