Boron-Doped Prussian Blue Cathode for Stable Battery Cycling
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Solution Overview
Problem
The existing Prussian blue analogs used as positive electrode active materials in secondary batteries face stability issues due to reactions with borohydride reducing agents, leading to hydrogen release, structural instability, and decreased electrical performance.
Innovation Solution
A boron-doped Prussian blue analog is introduced, where boron replaces carbon in the Prussian blue analog, enhancing the surface charge and orbital overlap of nitrogen elements, thereby improving the stability and cycle performance of the positive electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If borohydride is used as a reducing reagent in the preparation process of Prussian blue analog, then the Prussian blue analog can be synthesized, but hydrogen is released creating safety risks and strong alkali reacts with the Prussian blue analog causing structural instability
Solution Approach 1:
The patent changes the chemical composition parameters by introducing boron-doped Prussian blue analog with specific chemical formula AaMbM'(CN)6·dH2O where M and M' include boron. This compositional modification enables the material to achieve both synthesizability and structural stability, resolving the contradiction between ease of manufacture and reliability by fundamentally altering the material's chemical properties to resist alkali-induced degradation
Solution Approach 2:
The patent creates a composite material system by doping boron into the Prussian blue analog structure, forming a multi-element compound with enhanced properties. This composite approach combines the benefits of Prussian blue analog's electrochemical performance with boron's structural stabilization effect, achieving both manufacturability and structural integrity simultaneously
2Productivity
If high temperature heating is applied to evaporate solvent in the preparation process, then solvent removal is achieved, but borohydride reacts with water releasing large amount of hydrogen creating security risks
Solution Approach 1:
The patent modifies the thermal processing parameters by采用 low-temperature drying (60-80°C) instead of high-temperature heating. This parameter change eliminates the harmful hydrogen release effect while still achieving effective solvent removal, thus resolving the contradiction between productivity and safety by optimizing the temperature parameter to a safe range
Solution Approach 2:
The patent converts the potential harmful effect of borohydride-water reaction by controlling the drying temperature to remain below the activation threshold for hydrogen release. The low-temperature processing condition transforms what would be a dangerous high-temperature reaction into a safe evaporation process, achieving solvent removal without triggering harmful chemical reactions
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 boron-doped Prussian blue analog significantly improves the stability and cycle performance of the positive electrode active material, leading to enhanced energy storage capabilities and safety in secondary batteries.
Implementation Method 1
carbon element in the Prussian blue analog is replaced with boron element, causing electrons in a boron-nitrogen bond to be localized to nitrogen element
Implementation Method 2
an increase in a degree of orbital overlap, a decrease in length, and an increase in a covalency of a M-nitrogen chemical bond
Implementation Method 3
an increase in a degree of orbital overlap, a decrease in length, and an increase in a covalency of a M-nitrogen chemical bond
Data Source
AI summary
A positive electrode active material, including a boron-doped Prussian blue analog; and the Prussian blue analog has a chemical formula of AaMbM′c(CN)6·dH2O, in which A includes at least one of an alkali metal cation, an alkaline earth metal cation, Zn2+, and Al3+, M and M′ each independently includes at least one of Ni ion, Cu ion, Fe ion, Mn ion, Co ion, and Zn ion, and H2O is coordination water, 0<a≤2, 0<b≤1, 0<c≤1, 0≤d≤2; and relates to a preparation method, a secondary battery, and an electrical device. The stability of the positive electrode active material is improved, and thus improving a cycle performance of the corresponding secondary battery; and the preparation method of the positive electrode active material is simple in operation, mild in reaction conditions, and convenient for industrial application.