Non-aqueous Electrolyte Secondary Battery Short Circuit Prevention
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, are prone to minute short-circuits due to metal foreign matter entering the electrode assembly, which existing methods like using expensive separators with regulated gas permeation and applying negative electrode potentials struggle to prevent without impairing productivity and performance.
Innovation Solution
Incorporating a non-aqueous electrolyte with a lithium salt containing an SO2 bond and a compound with an isocyanate group, along with regulating the porosity and pore diameter of the negative electrode mixture layer, to enhance oxidative elution of metal foreign matter and inhibit reductive precipitation, thereby preventing dendrite formation and short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with regulated gas permeation degree is used to prevent short circuits caused by metal foreign matter, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific cyclic carboxylate compound (with 1,3-dioxolan-2-one or 1,3-dioxepan-2-one structure) and controlling its content at 5-50 mass% of total electrolyte. This chemical parameter change enables the electrolyte to form protective films that prevent dendrite formation, achieving short circuit prevention without requiring expensive specialized separators.
2Reliability
If a mechanism to apply negative electrode potential is provided inside the battery to perform long-time minute charge, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where the electrolyte composition itself (containing cyclic carboxylate at 5-50 mass%) automatically prevents dendrite formation through in-situ film formation on the negative electrode surface. This eliminates the need for external control mechanisms, additional electrodes, or complex control systems, thereby maintaining simple battery structure while achieving reliable short circuit prevention.
3Reliability
If strict management of metal foreign matter amount is implemented, then reliability is improved, but productivity decreases
Solution Approach 1:
The patent converts the potential harm of metal foreign matter into a beneficial effect by designing an electrolyte system that actively manages metal ions. The cyclic carboxylate compound (5-50 mass%) forms protective films that control metal ion deposition, transforming the uncontrolled harmful process of dendrite formation into a controlled beneficial process of uniform film formation, thereby preventing short circuits without requiring strict foreign matter management.
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 effectively inhibits the growth of dendrites and prevents short-circuits without compromising battery productivity or output characteristics, while also reducing the generation of gas during high-temperature storage.
Implementation Method 1
the metal foreign matter is oxidatively dissolved on a positive electrode side
Implementation Method 2
The eluted metal ion, which has a positive charge, moves to a negative electrode side
Implementation Method 3
reductively precipitates on a negative electrode surface to form a needle precipitation called a dendrite
Implementation Method 4
the non-aqueous electrolyte includes a lithium salt (A) containing an SO2 bond and a compound (B) containing an isocyanate group
Data Source
AI summary
This non-aqueous electrolyte secondary battery comprises: an electrode assembly in which a positive electrode and a negative electrode are laminated via a separator; and a non-aqueous electrolyte. The non-aqueous electrolyte includes an SO2 bond-containing lithium salt and an isocyanate group-containing compound. With respect to the mass of the non-aqueous electrolyte, the concentration of the lithium salt is preferably 0.1-2.5 mass % and the concentration of the compound is preferably 0.1-8 mass %.