Lithium Secondary Battery Electrolyte for Dendrite and Oxalic Acid Control
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Solution Overview
Problem
Lithium ion batteries face limitations in capacity improvement, and the use of oxalate complexes in lithium secondary batteries leads to positive electrode deterioration due to oxalic acid production, which is not adequately addressed by existing solutions.
Innovation Solution
Incorporating an oxalate salt with a polycyclic thiazole compound in the electrolyte suppresses dendrite formation on the negative electrode and reduces positive electrode deterioration by forming a protective SEI film, thereby improving charge-discharge efficiency and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxalate salt is used in the electrolyte to suppress dendrite formation, then negative electrode safety is improved, but positive electrode deterioration occurs due to oxalic acid production
Solution Approach 1:
A polycyclic compound acts as an intermediary substance that mediates between the oxalate salt and the positive electrode. The polycyclic compound preferentially reacts with oxalic acid to form a protective film, preventing oxalic acid from attacking the positive electrode while allowing the oxalate salt to continue suppressing dendrite formation.
Solution Approach 2:
The harmful oxalic acid produced by oxalate salt decomposition is converted into a beneficial protective film on the positive electrode surface. The polycyclic compound facilitates this transformation by reacting with oxalic acid to form a stable protective layer that prevents further electrode deterioration.
2Quantity of substance
If lithium ion batteries use graphite and alloy-type active materials to improve capacity, then battery capacity is improved, but the improvement approaches the limit
Solution Approach 1:
The invention changes the fundamental parameter from using intercalation materials (graphite, alloys) to using lithium metal, which has a higher theoretical capacity. This parameter change enables continued capacity improvement beyond the limits of conventional lithium ion battery materials.
3Stability of the object's composition
If a polycyclic thiazole compound is added to the electrolyte to protect the positive electrode, then positive electrode stability is improved, but electrolyte complexity increases
Solution Approach 1:
The polycyclic thiazole compound provides local protection specifically at the positive electrode surface where oxalic acid attack occurs. The compound concentrates its protective effect at the critical interface between electrolyte and positive electrode, rather than uniformly modifying the entire electrolyte system.
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 combination of oxalate salt and polycyclic thiazole compound enhances the battery's cycle characteristics and charge-discharge efficiency by preventing dendrite formation and reducing positive electrode degradation.
Implementation Method 1
Incorporating an oxalate salt with a polycyclic thiazole compound in the electrolyte suppresses dendrite formation on the negative electrode by forming a protective SEI film
Implementation Method 2
the metallic lithium dissolves in the electrolyte during discharge
Implementation Method 3
reduces positive electrode deterioration by forming a protective SEI film
Data Source
AI summary
A lithium secondary battery having a positive electrode, a separator, a negative electrode facing the positive electrode with the separator interposed therebetween, and an electrolyte, in which metallic lithium deposits on the negative electrode during charge. The electrolyte includes: an oxalate salt containing an oxalate complex as an anion, and a lithium ion as a cation; and a polycyclic compound having a thiazole ring and an aromatic ring sharing one side with the thiazole ring.