Silicon-Carbon Negative Electrode Pre-Lithiation for Stable Current Collection
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in achieving improved battery characteristics and reliability due to issues such as degradation, capacity reduction, and adverse effects on current collection performance caused by the expansion and contraction of silicon-based materials during charging and discharging.
Innovation Solution
The development of a non-aqueous electrolyte secondary battery with a negative electrode mixture containing pre-doped lithium ions, a silicon-based material, and a carbon-based material, along with a specific electrolyte composition, which includes lithium hexafluorophosphate and a boron-containing electrolyte salt, and a method for manufacturing this battery using electrochemical treatment and press-molding to enhance adhesion and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used in the negative electrode to increase capacity, then battery capacity is improved, but current collection performance deteriorates due to expansion and contraction during charging and discharging
Solution Approach 1:
Lithium ions are pre-doped into the silicon-based material before electrode assembly through electrochemical treatment. This preliminary action of pre-doping lithium ions compensates for the expansion and contraction effects during subsequent charging and discharging cycles, maintaining structural stability and current collection performance while preserving the high capacity benefit of silicon-based material
Solution Approach 2:
The electrochemical treatment process changes the parameter of lithium ion concentration within the silicon-based material. By controlling the pre-doping process, the lithium ion content is optimized to counteract volume changes during cycling, thereby maintaining both high capacity and reliable current collection
2Quantity of substance
If silicon-based material is used in the negative electrode to increase capacity, then battery capacity is improved, but adhesion deteriorates due to expansion and contraction during charging and discharging
Solution Approach 1:
Lithium ions are pre-doped into the silicon-based material before electrode assembly through electrochemical treatment. This preliminary action of pre-doping lithium ions compensates for the expansion and contraction effects during subsequent charging and discharging cycles, maintaining structural stability and current collection performance while preserving the high capacity benefit of silicon-based material
Solution Approach 2:
The electrochemical treatment process changes the parameter of lithium ion concentration within the silicon-based material. By controlling the pre-doping process, the lithium ion content is optimized to counteract volume changes during cycling, thereby maintaining both high capacity and reliable current collection
3Ease of manufacture
If conventional manufacturing methods are used, then manufacturing process is simple, but battery characteristics and reliability are insufficient
Solution Approach 1:
Lithium ions are pre-doped into the silicon-based material before electrode assembly through electrochemical treatment. This preliminary action of pre-doping lithium ions compensates for the expansion and contraction effects during subsequent charging and discharging cycles, maintaining structural stability and current collection performance while preserving the high capacity benefit of silicon-based material
Solution Approach 2:
The electrochemical treatment process changes the parameter of lithium ion concentration within the silicon-based material. By controlling the pre-doping process, the lithium ion content is optimized to counteract volume changes during cycling, thereby maintaining both high capacity and reliable current collection
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
This approach improves battery characteristics by reducing adverse effects on current collection and maintaining favorable charge and discharge cycle characteristics, leading to enhanced reliability and performance of the non-aqueous electrolyte secondary battery.
Implementation Method 1
pre-doping lithium ions to the negative electrode active material powder through electrochemical treatment in an electrolyte-containing liquid
Implementation Method 2
mixing at least the pre-doped negative electrode active material powder and a binder
Data Source
Figure 1(A)~1(B)
Figure 2
Figure 3
AI summary
There is provided a non-aqueous electrolyte secondary battery with excellent battery characteristics and excellent reliability. The non-aqueous electrolyte secondary battery includes at least a negative electrode for a non-aqueous electrolyte secondary battery including a negative electrode mixture, a positive electrode for a non-aqueous electrolyte secondary battery, and an electrolytic solution including an electrolyte and a solvent. The negative electrode mixture includes a negative electrode active material powder, the negative electrode active material powder includes a carbon-based material and a silicon-based material, a mixing ratio of the carbon-based material to the silicon-based material (carbon-based material (mass%)/silicon-based material (mass%)) is 90 mass%/10 mass% to 0 mass%/100 mass%, a negative electrode potential at a point of a battery voltage of 0 V is 3.2 Vvs(Li/Li+) or less in deep charging at a current rate of 0.001 ItA reaching the battery voltage of 0 V, and an electrolyte concentration in the negative electrode mixture is higher than an electrolyte concentration in the electrolytic solution present in the non-aqueous electrolyte secondary battery excluding the negative electrode mixture.