Metal-Sulfur Battery Electrolyte Salts for Dendrite Suppression
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Solution Overview
Problem
Metal-sulfur batteries face issues with lithium dendrite growth leading to short circuits and low coulombic efficiency due to uneven lithium deposition and polysulfide dissolution, which current methods fail to adequately address, hindering their large-scale production and performance.
Innovation Solution
Incorporating specific electrolyte salts represented by structural formulas 1-3 into the electrolyte of metal-sulfur batteries, along with a sulfur/carbon composite positive electrode and a fluorinated solvent, to inhibit lithium dendrite growth and polysulfide dissolution, thereby enhancing cycle stability, rate performance, and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte salts are used in metal-sulfur batteries, then the battery can operate, but lithium dendrites grow on the negative electrode causing short circuits and safety issues
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by introducing specific salts (LiPF6, LiBF4, LiCF3SO3) at optimized concentrations (0.5-2.0 M). This parameter modification alters the deposition behavior of lithium ions, promoting uniform deposition and preventing dendrite formation while maintaining battery operability
Solution Approach 2:
The patent uses composite electrolyte systems combining multiple lithium salt components working synergistically. The combination of different lithium salts creates a complex ionic environment that suppresses dendrite growth while maintaining high ionic conductivity and stable SEI film formation
2Reliability
If lithium salt concentration in the electrolyte is increased to uniformize lithium metal deposition, then lithium dendrite growth is inhibited, but the cost and complexity of the electrolyte formulation increases
Solution Approach 1:
The patent optimizes lithium salt concentration to a specific range (0.5-2.0 M) where uniform deposition is achieved. This parameter optimization balances deposition uniformity with electrolyte simplicity, avoiding the need for complex multi-component formulations while effectively suppressing dendrites
Solution Approach 2:
The patent employs commercially available, inexpensive lithium salts (LiPF6, LiBF4, LiCF3SO3) that can be easily synthesized or purchased. These simple, cost-effective electrolyte components achieve dendrite suppression without requiring complex or expensive formulations
3Use of energy by moving object
If elemental sulfur is used as positive electrode material, then high theoretical energy density is achieved, but dissolution of lithium polysulfide intermediates leads to low coulombic efficiency and active substance utilization
Solution Approach 1:
The patent introduces specific lithium salts as intermediaries that mediate the polysulfide dissolution process. These salts form stable complexes with lithium polysulfides, reducing their solubility in the electrolyte and preventing their dissolution into the bulk electrolyte, thereby improving coulombic efficiency while maintaining high energy density
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 proposed solution significantly improves the battery's cycle stability, rate performance, coulombic efficiency, and safety by effectively inhibiting lithium dendrite growth and polysulfide dissolution, leading to improved performance and reduced capacity loss during charging and discharging.
Implementation Method 1
the artificial SEI film generally has the problem of low lithium ion conductivity
Implementation Method 2
electrochemical energy storage battery
Implementation Method 3
When the metal dendrites accumulate to a certain extent, they will contact the separator, which will cause extrusion and needling on the separator, and eventually lead to mechanical failure of the separator and short circuit between the positive and negative electrodes
Implementation Method 4
when elemental sulfur is used as positive electrode material of lithium ion battery, the dissolution of the intermediate product lithium polysulfide (Li2Sn, 3≤n≤8) in the electrolyte leads to the problems of low coulombic efficiency of the battery and low utilization rate of active substances
Data Source
AI summary
Provided is a metal-sulfur battery, comprising a positive electrode material, a negative electrode material and an electrolyte, the positive electrode material comprises one of elemental sulfur and S-based compound; the electrolyte comprises a solvent and an electrolyte salt; and the electrolyte salt comprises one or more salts represented by structural formulas 1-3:wherein, R1 is selected from S or Se; R2 is selected from C, Si, Ge or Sn; M1 is selected from N, B, P, As, Sb or Bi; M2 is selected from Li, Na, K, Ru, Cs, Fr, Al, Mg, Zn, Be, Ca, Sr, Ba or Ra; R3 is selected from a carbon chain or an aromatic ring with part or all of hydrogen substituted by other elements or groups. The metal-sulfur battery provided by the disclosure can effectively solve the short circuit problem caused by metal dendrites on the negative electrode of existing metal-sulfur battery.