V2O5 Coated Lithium Battery Cathode for Corrosion Resistance
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Solution Overview
Problem
Rechargeable lithium batteries face corrosion issues with metal current collectors due to high pH levels in aqueous positive active material slurries, leading to increased resistance and pinholes, and existing solutions like molybdenum trioxide have low electrical conductivity, which deteriorates charge and discharge characteristics.
Innovation Solution
A positive active material composition is developed by coating vanadium pentoxide (V2O5) on lithium cobalt, nickel cobalt manganese, or nickel cobalt aluminum oxides using an organic solvent and heating, which prevents corrosion and enhances electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an aqueous binder is used to fabricate a positive electrode, then the positive active material provides unreacted alkali metal ions dissociated into water which dramatically increases the pH of the positive active material slurry, but this high pH causes corrosion of the metal current collector and generates H2 gas leading to pinholes and increased internal resistance
Solution Approach 1:
A protective coating layer comprising metal fluoride, metal oxide, or metal oxyfluoride is applied to the metal current collector surface. This intermediary layer acts as a barrier between the corrosive high-pH aqueous binder and the metal current collector, preventing direct contact and thus preventing corrosion and H2 gas generation while allowing the aqueous binder to be used for ease of manufacture
2Object-affected harmful factors
If molybdenum trioxide (MoO3) is used to prevent corrosion, then corrosion resistance is improved, but the low electrical conductivity of MoO3 increases electrode resistance and deteriorates charge and discharge characteristics
Solution Approach 1:
The protective coating is formed by reacting a metal-containing compound with a fluorinating agent to create metal fluoride, or by using metal oxide or metal oxyfluoride materials. These composite coating materials provide both corrosion resistance and maintain electrical conductivity, unlike pure MoO3. The coating can be applied as a thin layer to minimize resistance impact while providing sufficient protection
Solution Approach 2:
The invention changes the chemical composition parameters of the protective coating from low-conductivity materials like MoO3 to high-conductivity materials such as metal fluorides (e.g., AlF3, TiF3), metal oxides (e.g., Al2O3, TiO2), or metal oxyfluorides. This parameter change in material composition maintains both corrosion protection and electrical conductivity
3Object-affected harmful factors
If additional processing steps are implemented to coat metal oxides on current collector, then corrosion protection is improved, but the additional processing increases manufacturing cost
Solution Approach 1:
The formation of the protective coating is merged with the existing electrode fabrication process. The metal-containing compound and fluorinating agent are applied and reacted during the same manufacturing sequence as electrode assembly, eliminating the need for separate coating equipment or processes. This integration maintains corrosion protection while avoiding additional processing complexity
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 vanadium pentoxide coating effectively suppresses corrosion, reduces electrode resistance, and improves high rate capability and cycle-life characteristics of rechargeable lithium batteries by maintaining high electrical conductivity and preventing pinhole formation.
Implementation Method 1
a positive active material coated with a vanadium pentoxide
Implementation Method 2
mixing a positive active material, a vanadium pentaoxide (V2O5), and an organic solvent, agitating the mixture to evaporate the organic solvent
Implementation Method 3
heating the resultant mixture to prepare a positive active material coated with the vanadium pentaoxide
Data Source
AI summary
In an aspect, a positive active material composition for a rechargeable lithium battery including a positive active material coated with a vanadium pentaoxide (V2O5) and an aqueous binder, a positive electrode including the same, and a rechargeable lithium battery including the positive electrode is disclosed.