Aqueous Lithium Battery with Composite Electrodes
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Solution Overview
Problem
Lithium secondary batteries face challenges with low ionic conductivity in non-aqueous electrolytes, leading to deteriorated battery characteristics during high-rate charge and discharge, and existing aqueous electrolyte solutions do not achieve high energy density and stability.
Innovation Solution
A lithium secondary battery design incorporating a positive electrode with active materials like LiFe x M y PO 4 and Li 2 Fe x M y P 2 O 7, a negative electrode with Li 4 (Ti p N q ) 5 O 12, and an aqueous lithium ion-containing electrolyte, with conductive agents and a non-woven fabric separator, allowing for thicker electrodes and improved adhesiveness, thus enhancing stability and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If non-aqueous electrolyte is used to achieve high discharge voltage (3.6-3.7V), then high electric power is obtained, but ionic conductivity is significantly lower than aqueous electrolyte, causing deteriorated battery characteristics during high-rate charge and discharge
Solution Approach 1:
The patent changes the fundamental parameter of electrolyte type from non-aqueous to aqueous, while simultaneously adjusting the voltage operating range to 0-2V to accommodate the lower stability window of aqueous electrolytes. This parameter change enables achieving high ionic conductivity (close to aqueous electrolyte levels) while maintaining acceptable battery performance through optimized electrode materials and structure.
2Reliability
If aqueous electrolyte is used to improve ionic conductivity, then battery characteristics during high-rate charge and discharge are improved, but energy density and stability are insufficient
Solution Approach 1:
The patent employs composite electrode structures with multiple functional layers: active material layers (LiFePO4, Li2FeSiO4, Li4Ti5O12), conductive agent layers (acetylene black, carbon nanotubes), and binder layers. These composite structures optimize both ionic conductivity for high-rate performance and capacity for energy density, while the aqueous electrolyte provides high ionic conductivity and safety.
3Quantity of substance
If electrode thickness is increased to improve energy density, then capacity is increased, but adhesiveness and structural integrity may deteriorate
Solution Approach 1:
The patent applies different material compositions and properties to different layers of the electrode structure. The active material layer provides capacity, the conductive agent layer ensures electron transport and adhesion, and the binder layer provides mechanical integrity. This local differentiation of material quality allows thick electrodes to maintain both high energy density and structural integrity.
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 high stability and energy density at an average voltage of 2 V, with improved thermal safety and high input/output performance, enabling the removal of safety parts and reducing costs while maintaining performance.
Implementation Method 1
an electrolyte, wherein the positive electrode includes one or more positive electrode active materials selected from the group consisting of LiFe x M y PO 4
Implementation Method 2
the coating of the positive electrode comprising the positive electrode active material further includes one or more conductive agents selected from the group consisting of cobalt, nickel or copper, and cobalt oxide
Implementation Method 3
a separator disposed between the positive electrode and the negative electrode
Data Source
AI summary
Provided is a lithium secondary battery having high stability and high energy density. A lithium secondary battery includes a positive electrode and a negative electrode wherein the positive electrode includes one or more positive electrode active materials selected from LiFexMyPO4, Li2FexMyP2O7, Li3FexMy(PO4)3, and LiFexMyO2, and coated on at least one surface of a positive current collector, where M is at least one selected from cobalt (Co), nickel (Ni), manganese (Mn), (Al), (Sn), and (Sb), 0 < x ≤1, and 0 ≤y < 1, the negative electrode includes one or more negative electrode active materials selected from Li4(TipNq)5O12 and Li2(TipNq)3O7, and coated on at least one surface of a negative current collector, where N is at least one selected from Co, Ni, Mn, Al, Sn, and Sb, 0 < p ≤1, and 0 ≤q < 1, and the electrolyte includes a lithium (Li) ion-containing aqueous solution.