Vanadium-Enriched Cathode Material for Mn Dissolution Control
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Solution Overview
Problem
Manganese-based positive electrode active materials in batteries suffer from rapid capacity fading due to the dissolution of manganese ions and oxidative decomposition of the electrolytic solution, leading to poor cycle and storage performance.
Innovation Solution
A positive electrode active material with a core and a surface region enriched with element V, where the concentration of V in the surface region is higher than in the core, reduces metal ion dissolution and oxidative decomposition, improving structural stability and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If manganese-based positive electrode active materials are used, then high capacity and rich raw material sources are achieved, but rapid capacity fading occurs due to manganese ion dissolution
Solution Approach 1:
The patent applies local quality by creating a surface region with higher vanadium concentration than the core. This non-uniform distribution allows the surface to specifically address manganese ion dissolution and electrolyte oxidation, while the core maintains the high capacity lithium manganese phosphate structure. The surface region acts as a protective layer that locally modifies the material properties without changing the bulk composition.
Solution Approach 2:
The patent creates a composite structure with a lithium manganese phosphate core and a vanadium-containing surface region. This composite approach combines the high capacity of lithium manganese phosphate with the protective effects of vanadium, which reduces metal ion dissolution and electrolyte oxidation. The composite structure allows both materials to contribute their respective advantages.
2Quantity of substance
If manganese-based positive electrode active materials are used, then high capacity is achieved, but oxidative decomposition of electrolytic solution occurs leading to poor storage performance
Solution Approach 1:
The vanadium-containing surface region acts as an intermediary between the lithium manganese phosphate core and the electrolyte. It mediates the interaction by providing a protective barrier that prevents direct contact between the electrolyte and the reactive manganese-based material, thereby reducing oxidative decomposition while allowing ionic transport.
Solution Approach 2:
The surface region with enriched vanadium provides local protection against oxidative decomposition. The vanadium species in the surface region create a more stable chemical environment that resists oxidation, while the bulk material maintains its high capacity characteristics.
3Reliability
If element V is added to reduce metal ion dissolution, then cycle performance is improved, but material complexity increases
Solution Approach 1:
Instead of uniformly distributing vanadium throughout the material (which would increase complexity), the patent concentrates vanadium in the surface region only. This localized approach achieves the protective effect where it is most needed (at the surface where dissolution and oxidation occur) while keeping the bulk material simple and well-understood.
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 enhances the cycle and storage performance of batteries by reducing metal ion dissolution, particularly manganese ions, and minimizing oxidative decomposition, thereby improving the material's structural stability and ionic conductivity.
Implementation Method 1
the element V in the core can reduce the lattice change rate of the positive electrode active material, improve the structural stability of the positive electrode active material
Implementation Method 2
the element V can reduce the bond length variation of the Me-O bond (Me represents a metal element, such as a transition metal element, and particularly, Me may be Mn) during charging and discharging
Implementation Method 3
the element V in the first region not only can reduce the dissolution of metal ions (particularly manganese ions)
Implementation Method 4
the element V in the first region not only can reduce the dissolution of metal ions (particularly manganese ions), but also can reduce the oxidative decomposition of the electrolytic solution on the surface of the positive electrode active material
Implementation Method 5
the element V in the core can reduce the lattice change rate of the positive electrode active material, improve the structural stability of the positive electrode active material, and improve the ionic conductivity of the positive electrode active material
Data Source
AI summary
The present application provides a positive electrode active material and a preparation method thereof and a battery comprising same, and an electrical device. The positive electrode active material comprises a core and a first area formed on at least part of the surface of the core; the first area comprises a V element, and the mass concentration of the V element in the first area is denoted as W1; the core comprises a V element, and the mass concentration of the V element in the core is denoted as W2, then W1>W2.