Large-Channel Cathode Precursor for Faster Lithium-Ion Diffusion
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Solution Overview
Problem
Current methods for improving the cycling performance of ternary lithium-ion battery (LIB) cathode materials, such as doping and coating, do not effectively enhance the ion channel structure, leading to reduced specific capacity and stability issues.
Innovation Solution
A preparation method for an LIB cathode material precursor with a large channel is developed, involving the co-precipitation of nickel, cobalt, and manganese with sodium and ammonium, followed by calcination and soaking in water to remove sodium, thereby creating a precursor with a widened lithium ion diffusion channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If doping and coating methods are used to improve cycling performance, then cathode material stability is improved, but ion channel structure cannot be changed and specific capacity is reduced
Solution Approach 1:
The invention introduces a preliminary action by adding sodium ions during the precipitation process to pre-construct the crystal structure with expanded channels before the final cathode material formation. This preliminary structural modification ensures that the ion channels are already optimized for lithium ion transport, eliminating the need for post-processing coating that would block channels while maintaining cycling stability through the pre-designed structure.
Solution Approach 2:
The invention applies parameter changes by controlling the sodium ion concentration and precipitation conditions to precisely adjust the channel dimensions and crystal structure parameters. By varying the sodium content during precipitation, the ion channel size can be optimized to accommodate lithium ion transport while maintaining structural stability, thus improving both specific capacity and cycling performance simultaneously.
2Quantity of substance
If simple physical mixing is used to blend cathode materials, then compacted density is improved, but matrix structure is destroyed and no chemical bond is generated
Solution Approach 1:
The invention merges the benefits of physical mixing (high compacted density) with chemical bonding by introducing sodium ions that form chemical bonds within the crystal structure during precipitation. The sodium ions act as a bridging element that simultaneously achieves dense packing through structural optimization and strong chemical bonding, eliminating the need to choose between physical mixing and chemical bonding methods.
3Object-affected harmful factors
If coating materials are applied to cathode material, then contact with electrolyte is reduced, but ion channel is not changed and specific capacity is reduced
Solution Approach 1:
The invention uses sodium ions as an intermediary during the precipitation process to modify the crystal structure from within, rather than applying external coating materials. The sodium ions integrate into the crystal lattice and expand the channels internally, providing protection against electrolyte contact while simultaneously enhancing ion transport channels, thus avoiding the capacity loss associated with external coating approaches.
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 method results in a cathode material precursor with improved lithium ion deintercalation ability, leading to enhanced rate performance and cycling stability, as evidenced by the electrochemical performance tests.
Implementation Method 1
mixing a sodium hexanitrocobaltate aqueous solution, a nickel-manganese mixed salt solution, an oxalic acid solution, and aqueous ammonia to allow a reaction at a controlled temperature, a controlled pH, and a controlled ammonia concentration; and when a particle size of a reaction product reaches a target value, subjecting the reaction product to solid-liquid separation (SLS) to obtain a solid material
Implementation Method 2
subjecting the solid material to calcination to obtain a calcined material
Implementation Method 3
soaking the calcined material in water, and separating a solid phase to obtain the cathode material precursor with a large channel
Data Source
AI summary
The present application provides a preparation method for a positive electrode material precursor having a large channel, and an application thereof. The method comprises: mixing a sodium hexanitrocobaltate aqueous solution, a nickel-manganese mixed salt solution, an oxalic acid solution, and aqueous ammonia for reaction; calcining a solid material; and soaking the calcined material in water to obtain a positive electrode material precursor having a large channel. According to the present application, nickel-cobalt-manganese and sodium-ammonium are co-precipitated and sintered, and then sodium-ammonium is removed; and since the radius of sodium ions is greater than the radius of lithium ions, a large ion channel is left in a nickel-cobalt-manganese precursor framework, thereby facilitating the deintercalation of the lithium ions of a chemically sintered positive electrode material, widening a lithium ion diffusion channel, and remarkably improving the rate capability and the cycle performance of the material.