Lithium-Ion Cathode Material Processing for Carbonate and Gassing Control
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Solution Overview
Problem
Lithium ion battery cathode active materials face issues with high carbonate content leading to undesired gassing and reduced capacity upon cycling, and are sensitive to CO2 and moisture during storage, necessitating a method for improved electrochemical behavior and storage stability.
Innovation Solution
A process involving the synthesis of a mixed oxide (Li1+xTM1−xO2) at 750-1000°C in an oxidizing atmosphere, followed by cooling and treatment with BF3, SO2, or SO3 at 100-400°C, then cooling to 50°C or below, to reduce carbonate content and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-containing mixed transition metal oxides are produced by thermal treatment at 750-1000°C, then the cathode active material is formed, but high carbonate content remains leading to undesired gassing and reduced capacity
Solution Approach 1:
The patent applies parameter changes by modifying the chemical environment during cooling through acid treatment. The material is treated with acids (HF, HCl, H2SO4, HNO3, or a mixture) at controlled temperatures (50-200°C) to selectively remove carbonate impurities while preserving the lithium-containing mixed transition metal oxide structure. This chemical parameter change enables differentiation between desired product and unwanted carbonate byproducts.
Solution Approach 2:
The patent introduces acid as an intermediary substance to mediate the removal of carbonate from the cathode material. The acid acts as a selective reagent that reacts with carbonate to form volatile or soluble products, thereby eliminating the harmful carbonate content without damaging the active material. This intermediary enables indirect removal of the problematic component.
2Object-generated harmful factors
If washing with water is performed to reduce carbonate, then carbonate content decreases, but overall capacity is not improved
Solution Approach 1:
The patent changes the chemical parameter from neutral water to acidic solution, which fundamentally alters the interaction with carbonate. The acid provides protons that react with carbonate to form CO2 and water, enabling complete removal rather than mere dissolution. This parameter change transforms an ineffective washing process into an effective decarbonation treatment that also improves capacity.
3Ease of operation
If cathode active materials are stored under ambient conditions, then storage is convenient, but sensitivity to CO2 and moisture reduces stability
Solution Approach 1:
The patent applies preliminary action by performing acid treatment to remove carbonate and stabilize the material composition before storage. This pre-treatment creates a more stable material that is less sensitive to CO2 and moisture during subsequent storage, enabling convenient ambient storage without compromising stability. The preliminary stabilization prevents future degradation.
4Device complexity
If the cooling process is performed without acid treatment, then the process is simple, but gassing occurs upon contact with acidic electrolyte
Solution Approach 1:
The patent applies extraction by removing the harmful carbonate component through acid treatment during the cooling process. By extracting carbonate as CO2 gas during controlled acid treatment, the material is purified before final cooling, eliminating the source of gassing that would occur later upon contact with acidic electrolyte. This targeted extraction prevents the harmful effect.
Solution Approach 2:
The patent converts the potential harm of acid treatment (which could damage the material) into a benefit by carefully controlling the acid type, concentration, and temperature. The acid that could potentially harm the material is instead used to selectively remove carbonate, transforming a risky step into a beneficial purification process that eliminates gassing issues.
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 process results in improved cyclability, capacity retention, reduced gassing, and increased robustness of cathode active materials during storage, with enhanced initial capacity and cycling behavior.
Implementation Method 1
synthesizing a mixed oxide according to general formula Li1+xTM1−xO2 at a temperature in the range of from 750 to 1000° C. in an oxidizing atmosphere
Implementation Method 2
cooling down the material obtained from step (a) to a temperature in the range of from 100 to 400° C.
Implementation Method 3
adding at least one reactant selected from BF3, SO2, and SO3 at said 100 to 400° C.
Implementation Method 4
cooling down to a temperature of 50° C. or below
Data Source
AI summary
A process for making a cathode active material for a lithium ion battery is described. The process includes (a) a step of synthesizing a mixed oxide of formula Li1+xTM1−xO2 at a temperature ranging from 750 to 1000° C. in an oxidizing atmosphere, where TM is a combination of two or more transition metals of Mn, Co and Ni and, optionally, at least one more metal of Ba, Al, Ti, Zr, W, Fe, Cr, K, Mo, Nb, Mg, Na and V, and x is a number ranging from zero to 0.2, (b) a step of cooling down the material obtained from step (a) to a temperature ranging from 100 to 400° C., (c) a step of adding at least one reactant of BF3, SO2 and SO3 at the temperature of 100 to 400° C., and (d) a step of cooling down to a temperature of 50° C. or below.