Unveiling micro internal short circuit mechanism in a 60 Ah high-energy-density Li-ion pouch cell

Probing heat generation and release in a 57.5 A h high-energy-density Li-ion pouch cell with a nickel-rich cathode and SiOx/graphite anode

“…In extreme cases, hot spots could be generated and can be very harmful especially because SEI is generally the most vulnerable components at elevated temperatures. 56 Our previous study evidenced that the onset temperature of SEI decomposition of the SiO x /graphite blended anode can be as low as 72.03 C. 33 The successive discharge behavior of the blended anode indicates that the real discharge rates for both graphite and SiO x would be leveraged. The rate performance burden would be heavier for the component that contributes less capacity, SiO x in this case.…”

“…Assuming uniform temperature within each single laminate and liner temperature gradient along the direction vertical to the laminate stack from the cell center to the broad cell outer surface, the highest temperature at the cell center immediately aer the stop of the discharge was estimated to be as high as 98.7 C. This very high temperature is sufficient to damage the SEI, which can thermally decompose at a temperature as low as 72.03 C for the SiO x /graphite composite anode, as was proved in our previous study. 33 The signicant heat accumulation and delayed heat release behaviors of the large-format Li-ion cell suggest that the algorithm of the cooling system and the alarming system of the TMS should not rely merely on the real-time cell surface temperatures. A reliable TMS should take the history outputs, heat generation, and possible heat accumulation effect into consideration, and include the prediction of internal cell temperature rise into its target.…”

“…A previous study by our group has demonstrated that even a millivolt-level micro short circuit is sufficient to trigger a catastrophic re in largeformat cells with this material couple. 33 The high safety risks and worse consequences narrow the acceptable temperature windows of large-format HED cells and again emphasize the importance of a thorough understanding of the heat generation and release mechanisms. Unfortunately, until now research committed to these issues remain rare.…”

Mechanical Failure Mechanism of Silicon-Based Composite Anodes under Overdischarging Conditions Based on Finite Element Analysis

“…Safety issues in lithium-ion batteries have caused extensive concern due to the more widespread use in daily life and the rapidly increasing energy density. − Especially, with the development of electric and hybrid electric vehicles in which multiple-cell battery packs were used, overdischarge has become a potential safety risk. , Overdischarge can result in the mechanical failure of electrodes and thus induce rapid capacity decay and cycle life loss, , as well as even short circuit and thermal runaway in batteries. , Understanding the mechanical failure mechanism under overdischarging conditions and studying how to alleviate its harms are highly demanded. − …”

Solvent-Free Approach for Interweaving Freestanding and Ultrathin Inorganic Solid Electrolyte Membranes

“…Using a high-temperature sintering process can realize its high ionic conductivity but the flexibility of the membrane will lose. On the other hand, our recent nail penetration test indicates that the commercial PP separator is the weakest part of large-capacity pouch cells . Therefore, replacing the polymeric PP separator with thermally stable counterparts is believed to be an effective solution to improve battery safety.…”