Analysis of Moisture Penetration Mechanism into the Al-Pouch Type Lithium Ion Batteries

Abstract

초록: 본 논문에서는 파우치-타입 리튬이차전지의 수분 침투 경로를 파악하기 위해 금속 lead-tap이 부착되어 있는 파우치 타입 리튬이차전지 dummy 셀(셀 외부는 실제 파우치 타입 리튬이차전지와 동일하게 생겼으나 셀 내부에는 전해액만 존재하고 전극 및 분리막은 없는 셀을 말함)과 금속 lead-tap을 부착하지 않은 dummy 셀을 제작하여 고온/ 고습 환경에 보관하면서 시간의 경과에 따른 수분 함량 변화를 측정하여 금속 lead-tap 존재 여부가 파우치 타입 리튬 이차전지의 수분 침투성에 미치는 영향을 분석하였다. 실험 결과 파우치-타입 리튬이차전지의 수분 침투 경로는 2가 지로, 하나는 금속 lead-tap과 lead 필름 계면에 형성된 미세 기공 또는 결함이며 다른 하나는 CPP(cast polypropylene) 접착층임을 확인하였다.Abstract: The moisture penetration mechanism into the pouch type lithium ion battery (LiB) is systematically investigated. In order to clarify the path for moisture penetration into pouch type LiB, we prepared dummy cells assembled with lead-tap and dummy cells assembled without lead-tap, in which there are only electrolyte. The change of amount of moisture inside the samples was tracked during 8 weeks by storing them under high humidity condition (RH 90%). As a result, a large amount of moisture is detected in the dummy cells assembled with lead-tap. To understand such phenomena, the microstructure of interface between lead-tab and lead film was observed by SEM. We found that a large amount of microvoids was existing on the interface between lead-tap and lead film. This result implies that such microvoid might act as the path of moisture penetration for the pouch type LiB.

Zero fire battery concept: water-in-battery

“…A laminator and sealant lm with a multi-layered lm layer are selected as the main sealing materials of a seawater secondary battery, and the underwater exposed part of the WiB is heat-welded together with this lm. 22,23 Here's the sealing layers, which composes the multilayer/A: materials with excellent insulation, humidity, weather resistance, and wear barrier properties./B: thin lms that can block light, gas, and oxygen./C: the innermost sealing material capable of maintaining sealing and airtightness./D: an adhesive material that blocks and adheres to oxygen-containing gas and has excellent adhesion and xability.…”