Stranded Energy in Lithium-ion Energy Storage Systems

Stranded energy (SE) refers to electrical energy that remains inside a battery when there are no immediate means to discharge it, even when the battery is completely disconnected. Lithium-ion batteries are commonly used in ESS, however, in situations such as accidents or at end-of-life, the presence of SE can pose a significant safety risk during transportation (e.g., electrocution of personnel handling the battery, or thermal runaway events). SE can be difficult to assess and remove, especially in situations where the battery management system (BMS) is damaged, inaccessible, or simply not present.

TC would like to focus on large, high voltage (greater than 100Wh, above 100V-400V) lithium-ion ESS, as the intent is to study ESSs where SE may pose significant hazards to humans or the environment due to shock or fire. Lithium-ion batteries less than 300Wh are considered small batteries and should be excluded for the scope of the study. The key objective is to define hazards and challenges of dealing with SE as it relates to transportation depending on the type of ESS (grouped by size, use, cell form-factor/chemistry, etc.) and condition of the battery (end of life, post incident, defective), rather than focusing on any particular type of ESS (e.g., electric cars).

Transport Canada (TC) would like to better understand the hazards related to the presence of stranded energy (SE) in lithium-ion energy storage systems (ESS) during transportation and related handling and storage, and how these hazards vary by battery characteristics and environmental factors. The study should also explore strategies (including specific technologies for hazard reduction) as it relates to transportation of ESS with SE.

Thus, the objective of the study is to

1. Define the hazards caused by SE during transportation of lithium-ion ESSs and how they may vary depending on ESS type (electric vehicle (EV), solar installation, etc.), specification (voltage, capacity, chemistry), mode of transportation (excluding marine) and state of the ESS (end of life, post-incident, defective).

2. Identifying strategies/technologies for managing SE (i.e., would it be safer to leave the SE in the battery during transport or are there safe and practical means to remove the SE?) to reduce hazards and mitigate potential risks. This may include recommendations on potential areas of additional research.

For the purposes of this scope of work, “lithium-ion ESSs” include high voltage (above 100V-400V) lithium-ion batteries larger than 300Wh. The intent of this study is to focus on ESSs where SE could pose a serious safety hazard.

As part of identifying hazards of SE and gaps that may exist in achieving safe transportation of these ESSs, it is important to understand the relevant regulations, standards, and industry best practices currently in place. To support this aspect of the study:

? TC will provide an overview of the current requirements for transporting lithium-ion batteries (including when damaged or defective), and electric vehicles under the Transportation of Dangerous Goods Regulations.

TC is aware of current studies related to SE that center around emergency response to EV accidents, economical methods to de-energize small lithium-ion batteries for bulk transport at end of life and scanning technologies for battery health and re-use. To reduce duplication of work, this study should not focus on these topics.