Ca-Doped P2 Sodium Cathode Material for Stable Na Layer Cycling
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Solution Overview
Problem
Conventional positive electrode active materials with a P2-type structure have inadequate cycle characteristics due to the collapse of Na layers during sodium desorption, leading to decreased capacity and efficiency.
Innovation Solution
Incorporating Ca as a dopant in the Na-containing oxide with a P2-type structure, which functions as a pillar to stabilize the Na layers, thereby mitigating collapse and enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional P2-type positive electrode active materials are used, then the structure is simple and easy to manufacture, but the cycle characteristics deteriorate due to Na layer collapse during sodium desorption
Solution Approach 1:
The patent employs composite material strategy by doping Ca into the P2-type Na-containing oxide structure. The Ca element acts as a pillar that prevents Na layer collapse while maintaining the overall P2-type structure. This composite approach combines the advantages of the P2-type structure with the stabilizing effect of Ca doping, resolving the contradiction between cycle characteristics and structural simplicity.
Solution Approach 2:
The patent applies local quality modification by introducing Ca at specific doping concentrations (0.01 ≤ x ≤ 0.075 in the formula Na0.8-2xCaxMn0.66Ni0.34O2) to stabilize the Na layers locally. This localized doping approach maintains the overall P2-type structure while providing targeted stabilization where needed, improving cycle characteristics without excessive complexity.
2Reliability
If Ca doping is increased to stabilize Na layers, then cycle characteristics improve, but the amount of Na decreases which may reduce capacity
Solution Approach 1:
The patent optimizes the Ca doping concentration parameter within a specific range (0.01 ≤ x ≤ 0.075) to achieve the best balance between Na layer stabilization and Na content maintenance. By carefully controlling this parameter, the patent ensures sufficient Ca doping to prevent collapse while retaining enough Na for high capacity, resolving the contradiction between reliability and quantity of substance.
Solution Approach 2:
The patent applies partial action by using a controlled amount of Ca doping rather than excessive doping. This partial doping approach provides just enough stabilization to prevent Na layer collapse while minimizing the reduction in Na content, thereby maintaining high capacity alongside improved cycle characteristics.
3Quantity of substance
If Na content is increased to enhance capacity, then the capacity improves, but the Na layers become unstable and collapse during desorption
Solution Approach 1:
The patent introduces Ca as an intermediary element that mediates between the high Na content requirement for capacity and the Na layer stability requirement. The Ca acts as a structural pillar that supports the Na layers, allowing high Na content to be maintained without collapse during desorption, thus resolving the contradiction between quantity of substance and stability.
Solution Approach 2:
The patent applies beforehand cushioning by pre-introducing Ca doping into the structure before Na insertion and desorption cycles begin. This Ca doping creates a stable framework in advance that cushions against the collapse that would otherwise occur during Na desorption, enabling high Na content to be maintained stably throughout cycling.
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 Ca-doped Na-containing oxide exhibits improved cycle characteristics and higher capacity by maintaining the P2-type structure integrity during sodium insertion and desorption.
Implementation Method 1
Incorporating Ca as a dopant in the Na-containing oxide with a P2-type structure, which functions as a pillar to stabilize the Na layers
Data Source
AI summary
The disclosure relates to a positive electrode active material, a manufacturing method of a positive electrode active material, and a battery. The positive electrode active material of the present disclosure includes an Na-containing oxide. The Na-containing oxide has a P2-type structure. The Na-containing oxide includes, as constituent elements, at least: Na; Ca; at least one transition metal element among Mn, Ni, and Co; and O.