Silicate Cathode Flake Structure for Li-Ion Energy Density
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Solution Overview
Problem
Current lithium ion battery technology faces issues such as initial cycle irreversibility, electrode degradation, and high costs due to limitations in capacity and rate capability, particularly with oxide positive electrodes, which affect storage capacity and safety.
Innovation Solution
The development of a silicate cathode with a flake-like structure, specifically a mixed transition metal silicate coated with carbon, which enhances energy density and reduces costs by allowing two electrons per transition metal and improving lithium ion distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxide positive electrodes are used to achieve high capacity, then energy density is improved, but electrode degradation and metal dissolution occur leading to reduced reliability
Solution Approach 1:
The patent uses composite materials by combining silicate structure with transition metal elements (Li2MnSiO4, Li2FeSiO4, Li2CoSiO4, or Li2NiSiO4) to create a cathode material that achieves high capacity (nearly three times that of current lithium-cobalt-oxygen electrodes) while maintaining structural stability and preventing metal dissolution, thus resolving the contradiction between energy density and reliability
2Use of energy by moving object
If oxide positive electrodes are used to achieve high capacity, then energy density is improved, but cost significantly increases due to cobalt and nickel usage
Solution Approach 1:
The patent changes the chemical composition parameters by substituting expensive cobalt and nickel with more affordable transition metals (manganese, iron, cobalt, or nickel in controlled amounts) while maintaining the silicate crystal structure, achieving high capacity (nearly three times that of current lithium-cobalt-oxygen electrodes) at significantly reduced cost
3Ease of manufacture
If phosphate positive electrodes are used to reduce cost, then manufacturing cost is reduced, but capacity is limited due to intrinsically large band gap
Solution Approach 1:
The patent changes the material composition from phosphate to silicate structure, which has different electronic and ionic transport properties. The silicate structure with transition metals achieves both cost reduction (avoiding expensive cobalt-nickel-phosphate systems) and high capacity (nearly three times that of current electrodes) by enabling two electrons per transition metal
4Use of energy by moving object
If oxide positive electrodes are used to achieve high capacity, then energy density is improved, but safety deteriorates due to exothermic reactions and thermal run-away risk
Solution Approach 1:
The patent converts the potential harm of high-capacity oxide electrodes that cause thermal run-away into benefit by using silicate-based materials with transition metals that provide high capacity (nearly three times that of current lithium-cobalt-oxygen electrodes) while inherently preventing exothermic reactions and oxygen generation, thus eliminating safety risks
Data Source
AI summary
Silicate cathodes for lithium ion batteries are provided along with methods of forming a silicate. Olivine structures are substituted with a lithium ion. The substituted Olivine structures are combined to form flake-like sheets having an orientation that facilitates passage of lithium ions. Related methods of forming a cathode are provided.