Na Composite Oxide Aqueous Battery With Polyphosphate Electrolyte
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Solution Overview
Problem
There is a demand for a novel material usable as an active material with Na (sodium) which is a resource relatively abundantly present, in an aqueous battery with an aqueous electrolyte solution with potassium polyphosphate.
Innovation Solution
An aqueous battery comprising a positive electrode, an aqueous electrolyte solution, and a negative electrode, where the positive and negative electrode active materials include composite oxides containing Na, at least one transition metal element of Fe, Ti, Ni, and Mn, and the electrolyte solution contains water and potassium polyphosphate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aqueous electrolyte solutions are used, then the battery structure is simple, but the potential window is narrow and electrode decomposition occurs during charge-discharge cycles
Solution Approach 1:
The patent employs a composite electrolyte system combining potassium polyphosphate (KPP) with specific concentrations of KOH (3-13 mol/kg) and Na2SO4 (0.5-3 mol/kg). This composite approach creates synergistic effects where KPP provides wide potential window and electrode stability, while KOH enhances ionic conductivity and Na2SO4 prevents freezing, resolving the contradiction between electrode stability and electrolyte complexity.
Solution Approach 2:
The patent optimizes specific concentration parameters of electrolyte components to achieve desired performance. By controlling KOH concentration at 3-13 mol/kg, Na2SO4 at 0.5-3 mol/kg, and KPP at 1-6 mol/kg, the system achieves wide potential window, high ionic conductivity, and freeze protection, transforming the electrolyte from a simple to an optimized composite system.
2Reliability
If high concentration of electrolyte is used, then ionic conductivity improves, but viscosity increases and freezes at low temperatures
Solution Approach 1:
The patent adds Na2SO4 at concentrations of 0.5-3 mol/kg to the electrolyte system. This parameter change serves dual purposes: it depresses the freezing point of the electrolyte solution to prevent freezing at low temperatures, while maintaining adequate ionic conductivity for battery operation.
3Adaptability or versatility
If simple aqueous electrolyte is used, then manufacturing is easy, but the battery cannot utilize Na-based active materials effectively
Solution Approach 1:
The patent develops a composite aqueous electrolyte containing potassium polyphosphate, KOH, and Na2SO4. This composite formulation enables the battery to utilize Na-based active materials like NaFeO2, NaNi0.8Co0.1Mn0.1O2, and Na0.44MnO2 effectively, expanding active material compatibility while maintaining practical manufacturability through straightforward dissolution of salts in water.
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 can be charged and discharged effectively by combining the specified active materials and electrolyte solution, maintaining stability and performance even at low temperatures.
Implementation Method 1
the aqueous electrolyte solution comprises water and potassium polyphosphate dissolved in the water
Implementation Method 2
one of or both the positive electrode active material and the negative electrode active material comprise a composite oxide
Data Source
AI summary
Disclosed is a novel active material operatable in an aqueous battery. The aqueous battery of the present disclosure includes a positive electrode, an aqueous electrolyte solution and a negative electrode. The positive electrode includes a positive electrode active material, and the negative electrode includes a negative electrode active material. One of or both the positive electrode active material and the negative electrode active material include(s) a composite oxide. The composite oxide contains Na, at least one transition metal element of Fe, Ti, Ni and Mn, and O. The aqueous electrolyte solution contains water and potassium polyphosphate dissolved in the water.