Doped Recycled Cathode Materials for Crack-Resistant Cycle Life
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Solution Overview
Problem
Conventional lithium-ion battery recycling methods face challenges due to the unknown history and varying quality of recycled cathode materials, which can affect the performance of cathode material precursors and the resulting cathode materials, including issues with cycle life, surface cracking, and tap density.
Innovation Solution
The process involves aggregating recycled lithium-ion battery materials to form a 'black mass,' which is then leached with an acidic solution to create a leach solution. This solution is adjusted to a targeted metal ratio and doped with specific salts before coprecipitation, followed by sintering with lithium salts and additional dopants to produce a doped cathode material with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional recycling methods are used to produce cathode materials from recycled batteries, then the process is simpler and faster, but the cycle life and surface quality of the resulting cathode material deteriorate due to unknown history and varying quality of recycled materials
Solution Approach 1:
The patent applies preliminary action by adding dopant salts to the leach solution before coprecipitation of the cathode material precursor. This pre-doping approach modifies the surface properties and internal structure of the material during formation, preventing surface cracking and improving cycle life before the material is even synthesized. The dopant is incorporated into the crystal structure during the precipitation process itself, rather than attempting to fix defects afterward.
Solution Approach 2:
The dopant salt acts as an intermediary substance that mediates between the recycled battery materials and the final cathode product. The dopant (such as aluminum or magnesium salts) incorporates into the cathode material structure during coprecipitation, serving as a structural modifier that improves surface morphology and reduces cracking. This intermediary element bridges the quality gap in recycled materials by providing structural reinforcement at the crystal level.
2Manufacturing precision
If high purity battery grade materials are used, then the quality and performance of recycled cells is improved, but the cost and difficulty of achieving 99.5% purity increases significantly
Solution Approach 1:
The patent applies parameter changes by modifying the chemical environment during coprecipitation through the addition of dopant salts. By changing the composition parameters of the leach solution (adding specific dopant concentrations), the process achieves improved surface morphology and reduced surface cracking in the precipitated cathode material. This chemical parameter modification allows recovery of recycled materials without requiring extreme purification to 99.5% battery grade, thus reducing manufacturing complexity while maintaining product quality.
3Reliability
If dopant salts are added during coprecipitation, then surface morphology and cycle life are significantly improved, but the process complexity and number of steps increase
Solution Approach 1:
The patent merges the doping step with the coprecipitation step by adding dopant salts to the leach solution before the precipitation reaction occurs. This combination means that the dopant is incorporated into the cathode material structure during the formation process itself, rather than requiring a separate doping step afterward. The leach solution serves dual purposes: as the medium for metal extraction and as the vehicle for dopant delivery, thus combining multiple functions into one process stage.
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 addition of dopant salts significantly improves the surface morphology and cycle life of the cathode material, reducing surface cracking and enhancing tap density, resulting in a cathode active material with single crystal morphology, narrow particle size span, and high tap density.
Implementation Method 1
Leaching of the black mass with an aqueous acidic solution forms a leach solution having a ratio of metallic elements
Implementation Method 2
The charge material metal salts in the selected ratio and the first dopant are coprecipitated from the leach solution, generally by pH adjustment, to form a doped charge material precursor
Implementation Method 3
which is then sintered with a lithium salt and a second dopant to form a sintered doped cathode material
Data Source
AI summary
In a battery recycling process, a recycling stream including charge material metals from exhausted Li-ion batteries is aggregated or otherwise comminuted to generate recycled battery charge material having comparable or improved cycle life as well as recycled charge material precursor having fewer cracking defects using doping substances in both a coprecipitation phase and a sintering phase of the recycling sequence. Prior to coprecipitation of a cathode material precursor, a leach solution of comingled charge material metals is produced, the ratio of the charge material metals is adjusted based on recycled battery specifications, and a relatively small quantity of a first dopant is added. The doped precursor, a lithium salt, and a second dopant are combined and sintered to form a doped cathode material having a single crystal morphology and a higher tap density than the doped cathode precursor.