H2NiP2O7 Cathode for Nickel Hydrogen Battery Voltage Stability
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Solution Overview
Problem
Conventional nickel hydrogen batteries using β-type nickel hydroxide as cathode active material suffer from a decrease in battery voltage after charge due to the formation of γ-type nickel oxyhydroxide, leading to reduced capacity and memory effect issues.
Innovation Solution
Incorporating H2NiP2O7 as the cathode active material, which has a crystal structure composed of NiO6 octahedra and PO4 tetrahedra, suppressing changes in crystal structure during charging and preventing the formation of γ-type nickel oxyhydroxide, thereby maintaining battery voltage and preventing memory effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If β-type nickel hydroxide is used as cathode active material, then the battery can be charged and discharged repeatedly, but the battery voltage decreases after charge due to formation of γ-type nickel oxyhydroxide
Solution Approach 1:
The invention changes the crystal structure parameter of the cathode active material from layered β-Ni(OH)2 to three-dimensional framework H2NiP2O7, which prevents the phase transformation to γ-NiOOH during charging, thereby maintaining voltage stability while enabling repeated charge-discharge cycles
Solution Approach 2:
The invention uses H2NiP2O7 as a composite cathode active material that combines nickel-based electrochemical activity with a phosphorus-containing three-dimensional framework structure, achieving both cycle stability and voltage maintenance
2Ease of operation
If conventional cathode active materials are used, then the battery can operate, but memory effects occur requiring forced discharges or refresh cycles
Solution Approach 1:
By changing the crystal structure from layered to three-dimensional framework, the invention eliminates the memory effect phenomenon, allowing the battery to operate without forced discharges or refresh cycles, thereby simplifying operation and maintenance
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 use of H2NiP2O7 in the nickel hydrogen battery effectively suppresses voltage decrease after charge and prevents memory effects, allowing for higher state of charge and stable operation without the need for forced discharges or refresh cycles.
Implementation Method 1
the cathode active material includes H2NiP2O7 having a crystal structure comprising at least one NiO6 octahedron and at least one PO4 tetrahedron
Implementation Method 2
the NiO6 octahedra may share edges with the NiO6 octahedra adjacent thereto
Implementation Method 3
the PO4 tetrahedra may share apices with the PO4 tetrahedra adjacent thereto
Implementation Method 4
an electrolyte layer in contact with the cathode and the anode
Implementation Method 5
H2NiP2O7 has a three-dimensional framework formed by sharing oxygen atoms included in the at least one NiO6 octahedron and the at least one PO4 tetrahedron
Data Source
AI summary
A nickel hydrogen battery configured to suppress a decrease in battery voltage. The battery comprises a cathode containing a cathode active material, an anode containing an anode active material, and an electrolyte layer in contact with the cathode and the anode. The cathode active material contains H2NiP2O7 having a crystal structure including at least one NiO6 octahedron and at least one PO4 tetrahedron.