A thermal-runaway retardant (TRR) of lithium-ion batteries (LIBs), dibenzylamine (DBA), is investigated. In a TRR-modified LIB, DBA can be encapsulated in packages made of inert materials. When the LIB is subjected to mechanical abuse, the packages would be broken apart and the TRR is released. In nail penetration and impact tests, addition of 4 wt% DBA reduces the temperature increase of fully charged LIR-2450 cells by nearly 50%. The influence of TRR packages on the cycling performance of LIBs is negligible. The working mechanism of DBA is associated with the decrease in electrolyte conductivity, the increase in charge transfer resistance, and the reduction in lithium ion (Li +) transference numbers.

Summary We investigate the effects of thermally sensitive binder (TSB) on the temperature increase of lithium‐ion battery (LIB) coin cell subjected to severe mechanical abuse. The TSB is poly(vinylidenefluoride‐co‐hexafluoropropylene) (PVDF‐HFP), similar to conventional poly(vinylidenefluoride) (PVDF) binder but with a significant hexafluoropropylene (HFP) content. The testing data show that by using TSB, the peak temperature increase of nail‐penetrated LIB coin cell can be reduced by 20% to 40%, attributed to the softening of TSB that begins from ~80°C. The cycling performance of the LIB cells is also characterized. This research sheds light on the development of thermal‐runaway mitigation techniques.

Mechanical abuse often causes thermal runaway of lithium-ion battery (LIB). When a LIB cell is impacted, radial cracks can be formed in the current collector, separating the electrode into petals. As separator ruptures, the petals on positive and negative electrodes may contact each other, forming internal short circuit (ISC). In this study, we conducted an experimental investigation on LIB coin cells with current collectors modified by surface notches. Our testing results showed that as the current collector contained appropriate surface notches, the cracking mode of electrode in a damaged LIB cell could be adjusted. Particularly, if a complete circumferential crack was generated, the petals would be cut off, which drastically reduced the area of electrode involved in ISC and the associated heat generation rate. A parameterized study was performed to analysis various surface-notch configurations. We identified an efficient surface-notch design that consistently led to trivial temperature increase of ISC.

This work introduces a new mechanically triggered thermal runaway mitigation mechanism. The homogenizer of electrode failure (HEF), multiwall carbon nanotube (MWCNT), was added into LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532) battery electrodes. We have studied the effect of the HEF additive on the internal electrical resistance and the mechanical impact resistance of the electrodes. The additional MWCNTs reduced the internal electrical resistance of electrodes before mechanical abuse. Upon mechanical abuse, they could mitigate internal shorting and thermal runaway at normal battery working temperature. V

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