Nickel Oxide and Phosphate Coated Battery Electrode
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with transition metal elution from positive electrode active materials, leading to potential short circuits and increased resistance due to reactions with hydrogen fluoride, and existing solutions either fail to adequately suppress elution or result in excessive resistance when using nickel oxide surface layers.
Innovation Solution
A non-aqueous electrolyte secondary battery design featuring a positive electrode plate with a nickel oxide layer of 3 to 200 nm thickness and a nickel phosphate layer of 1 to 50 nm thickness, applied in order, to suppress transition metal elution and resistive increases, while maintaining battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel oxide layer is applied to the surface of the positive electrode active material to suppress transition metal elution, then the elution of transition metal is reduced, but the resistance of the positive electrode plate increases
Solution Approach 1:
The surface coating is divided into two distinct layers: a nickel oxide layer (3-200 nm) that suppresses transition metal elution, and a nickel phosphate layer (1-50 nm) that reduces resistance. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between elution suppression and resistance reduction.
Solution Approach 2:
The patent uses a composite coating structure combining nickel oxide and nickel phosphate materials. The nickel oxide provides elution suppression while the nickel phosphate provides low resistance, creating a composite surface layer that achieves both objectives simultaneously.
2Reliability
If the nickel oxide layer thickness is increased to improve elution suppression, then transition metal elution is further reduced, but the positive electrode plate resistance increases significantly
Solution Approach 1:
The patent optimizes the thickness parameters of both layers: nickel oxide layer at 3-200 nm and nickel phosphate layer at 1-50 nm. By controlling these parameters within specific ranges, the patent achieves effective elution suppression while maintaining low resistance, resolving the contradiction between elution suppression effectiveness and resistance control.
3Reliability
If a metal oxide coating is applied to suppress transition metal elution, then elution is reduced, but the battery output performance deteriorates due to increased resistance
Solution Approach 1:
The nickel phosphate layer acts as an intermediary between the nickel oxide layer and the electrolyte, providing a low-resistance pathway for lithium ion transport while allowing the nickel oxide layer to perform its elution suppression function. This intermediary layer resolves the contradiction between elution suppression and power output.
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
Effectively prevents transition metal elution and reduces positive electrode plate resistance, even under low temperature conditions, by controlling the thickness of the nickel oxide and nickel phosphate layers, ensuring stable battery output.
Implementation Method 1
Since a layer formed from nickel oxide having a low activity is provided on the surface of the positive electrode active material, in particular, on the surface of the part of the positive electrode active material located as the surface of the positive electrode active material mixture layer, for example, even if hydrogen fluoride is present in the battery, the reaction between the positive electrode active material and hydrogen fluoride can be suppressed.
Implementation Method 2
the second layer formed from nickel phosphate suppresses the increase in thickness of the first layer formed from nickel oxide when the battery is stored in a charged state
Data Source
AI summary
A non-aqueous electrolyte secondary battery has a positive electrode plate including a positive electrode active material mixture layer which contains as a positive electrode active material, a lithium transition metal composite oxide containing nickel; a negative electrode plate; a non-aqueous electrolyte including a lithium salt containing fluorine. In this non-aqueous electrolyte secondary battery, on a part of the positive electrode active material located as a surface of the positive electrode active material mixture layer, a first layer formed from nickel oxide and a second layer formed from nickel phosphate are provided in this order, the first layer has a thickness of 3 to 200 nm, and the second layer has a thickness of 1 to 50 nm.