Lithium Secondary Battery Electrolyte for Dendrite Suppression
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Solution Overview
Problem
Lithium secondary batteries face challenges with dendrite formation during charging and discharging, leading to increased specific surface area, side reactions, and deteriorated discharge capacity and cycle characteristics, despite efforts to suppress dendrite deposition being insufficient.
Innovation Solution
Incorporating specific cations (Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, Al) and oxalate complex anions (e.g., B(C2O4)2—, BF2(C2O4)—, P(C2O4)3—, PF2(C2O4)2—, PF4(C2O4)--) in the nonaqueous electrolyte to stabilize lithium metal deposition and inhibit dendrite formation, forming a stable film on the negative electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode active material to achieve higher capacity, then battery capacity increases, but dendrite formation occurs during charging
Solution Approach 1:
The patent introduces a specific electrolyte composition containing LiPF6 and GBL as intermediary substances between the lithium metal and the electrode. This electrolyte system mediates the lithium deposition process, enabling high capacity utilization while suppressing dendrite formation through controlled lithium ion transport and uniform deposition behavior.
Solution Approach 2:
The patent changes the physical and chemical parameters of the electrolyte system by using a specific concentration range of LiPF6 (0.5-2.0 mol/L) and GBL (10-30 vol%). These parameter changes optimize the electrolyte's conductivity, viscosity, and solvation properties, leading to improved lithium deposition uniformity and suppressed dendrite growth while maintaining high battery capacity.
2Area of stationary object
If dendrite is generated on negative electrode, then specific surface area increases, but side reactions increase and discharge capacity deteriorates
Solution Approach 1:
The patent optimizes the electrolyte composition parameters, specifically using LiPF6 at 0.5-2.0 mol/L and GBL at 10-30 vol%, to control the lithium deposition morphology. These parameter changes promote uniform lithium distribution and reduce specific surface area increase, thereby minimizing side reactions and energy loss.
Solution Approach 2:
The GBL component acts as a mediator that modulates the interaction between lithium ions and the electrode surface. It forms a stable solvation sheath around lithium ions, controlling their deposition behavior and preventing excessive surface area increase that would lead to harmful side reactions.
3Reliability
If conventional electrolyte composition is used to suppress dendrite, then some dendrite suppression is achieved, but cycle characteristics improvement is limited
Solution Approach 1:
The patent employs a composite electrolyte system combining LiPF6 salt and GBL solvent in specific proportions. This composite material approach creates synergistic effects where LiPF6 provides ionic conductivity and GBL provides solvation stability, together achieving superior dendrite suppression and cycle life extension compared to conventional single-component electrolytes.
Solution Approach 2:
The patent systematically optimizes the concentration parameters of LiPF6 (0.5-2.0 mol/L) and GBL (10-30 vol%) to achieve the best balance between dendrite suppression and cycle characteristics. This parameter optimization reveals that specific concentration ranges provide maximum benefit for long-term cycling stability and dendrite-free operation.
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 solution significantly improves cycle characteristics by stabilizing lithium metal deposition and suppressing dendrite formation, resulting in enhanced capacity retention rates.
Implementation Method 1
a lithium metal deposits on the negative electrode at the time of charging
Implementation Method 2
the lithium metal is dissolved in the nonaqueous electrolyte at the time of discharging
Data Source
AI summary
A lithium secondary battery including a positive electrode, a negative electrode, a lithium ion conductive nonaqueous electrolyte, and a separator disposed between the positive electrode and the negative electrode; on the negative electrode, a lithium metal deposits at the time of charging, the lithium metal dissolves in the nonaqueous electrolyte at the time of discharging; the nonaqueous electrolyte contains a cation and an anion; the cation includes a lithium ion, and at least one cation X selected from the group consisting of Na, K, Rb, Cs, Fr, Mg, Ca, Sr, Ba, and Al; and the anion includes an oxalate complex anion Y.