Crystalline LiBOB Purification for Battery Electrolyte Clarity
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Solution Overview
Problem
Existing methods for producing lithium bis(oxalato)borate (LiBOB) result in impure forms contaminated with water, acid components, and insoluble by-products, leading to turbid solutions and difficulties in handling due to the formation of solvated complexes with solvents like acetonitrile, which are undesirable in lithium batteries.
Innovation Solution
A process involving the use of cyclic 5-membered ring esters like 1,3-dioxolan-2-ones or γ-lactones for recrystallization of LiBOB, producing a coarsely crystalline, substantially cuboid LiBOB with low dust content and minimal solvent residues, ensuring the LiBOB is completely soluble and free from solvates like acetonitrile, achieving clear solutions with reduced turbidity and improved handling properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LiBOB is produced by conventional methods (reaction of lithium hydroxide/carbonate with boric acid/oxide and oxalic acid), then LiBOB can be synthesized, but the product is contaminated with water, acid components, and insoluble by-products resulting in turbid solutions
Solution Approach 1:
The patent extracts and removes harmful impurities (water, acid components, insoluble by-products) from the LiBOB product through a specific purification process involving filtration and washing steps, thereby achieving high purity without requiring complex multi-stage purification procedures
Solution Approach 2:
The patent changes the physical and chemical parameters of the purification process, specifically using controlled filtration through membranes with defined pore sizes and washing with specific solvents, to achieve complete removal of impurities while maintaining product integrity
2Ease of operation
If crude LiBOB is dissolved in aprotic solvents like esters or nitriles, then the solution can be prepared, but extremely turbid solutions form with insoluble proportions between 0.5 and 2 wt.% and turbidities of more than 100 NTU
Solution Approach 1:
The patent applies preliminary purification actions to the LiBOB before dissolution, including filtration through membranes and washing with specific solvents, to remove all insoluble impurities in advance, ensuring that the subsequent dissolution in aprotic solvents produces completely clear solutions without any turbidity
Solution Approach 2:
The patent changes the purity parameter of LiBOB to extremely high levels (less than 0.01 wt.% insoluble residue) through controlled purification processes, which directly enables complete solubility in aprotic solvents and eliminates turbidity issues
3Manufacturing precision
If LiBOB is recrystallized from acetonitrile and vacuum-dried, then solvate-free LiBOB can be obtained, but the product forms as fine dust that is extremely difficult to handle
Solution Approach 1:
The patent changes the crystallization parameters by using controlled cooling rates and specific solvent systems to produce coarse crystalline structures instead of fine powders, while simultaneously achieving high purity through the crystallization process itself, thereby eliminating the need for vacuum drying that creates difficult-to-handle dust
4Ease of operation
If LiBOB is produced with high purity to ensure complete solubility, then clear solutions are achieved, but the production process becomes more complex requiring multiple purification steps
Solution Approach 1:
The patent merges multiple purification functions (filtration, washing, and crystallization) into a single integrated process sequence, where each step builds on the previous one to progressively remove impurities, achieving complete solubility without requiring separate complex purification units or multiple independent processing stages
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 yields LiBOB with less than 0.1 wt% insoluble residue, turbidity of 100 NTU or less, and dust content below 10 wt%, resulting in a stable, easily handled, and solvent-free crystalline form suitable for lithium-ion batteries, enhancing cycle stability and safety.
Implementation Method 1
A process involving the use of cyclic 5-membered ring esters like 1,3-dioxolan-2-ones or γ-lactones for recrystallization of LiBOB
Implementation Method 2
producing a coarsely crystalline, substantially cuboid LiBOB with low dust content and minimal solvent residues
Data Source
AI summary
A crystalline, completely soluble lithium bis(oxalato)borate (LiBOB), to a method for producing the same and to the use of the lithium bis(oxalato)borate.