Transport container for a damaged lithium-ion battery

Abstract

Transport container (10) for a damaged lithium-ion battery (12), comprising a gas-permeable inner housing (14) designed to accommodate the lithium-ion battery (12), and an outer housing (16) designed to accommodate the inner housing (14) and to equalize pressure with the environment, wherein the inner housing (14) and the outer housing (16) are dimensioned such that an inner space is created between the inner housing (14) and the lithium-ion battery (12) and an outer space is created between the inner housing (14) and the outer housing (16), and wherein the inner and / or outer space contains a filling of an absorbent, thermally stable filling material, characterized in that the filling material in the inner and / or outer space contains a zeolite.

Description

[0001] The invention relates to a transport container for a damaged lithium-ion battery. State of the art

[0002] Lithium-ion batteries have long been used in various electronic devices. Due to their very high energy density, they offer significant weight advantages over other battery technologies as applications become increasingly miniaturized. These advantages are also being utilized more and more frequently in electric vehicles.

[0003] Lithium-ion batteries consist of at least one negative electrode (anode: for example, graphite, amorphous carbon) and one positive electrode (cathode: for example, LiCoO2, LiMn2O4, LiFePO4). Charging and discharging the battery cell releases lithium. + -ions are reversibly intercalated or deintercalated at the electrodes.

[0004] The binder material for the electrodes is often polyvinylidene fluoride (PVDF) with conductive additives. Currently, mixtures of organic liquids (for example, ethylene carbonate, propylene carbonate, dimethyl carbonate, dimethyl ethyl carbonate) mixed with a conducting salt (usually LiPF6) are preferred as electrolytes. Various electrolyte additives are also used to improve the battery's properties (for example, as overcharge protection and conducting salt stabilizers).

[0005] To prevent mechanical instability and the ingress of external substances (such as moisture and dust), the battery cells must be appropriately protected. In automotive applications, the preferred cell designs are pouch cells, wound cylindrical cells, and prismatic cell designs. Currently, cells with a nominal capacity of 3 to 60 Ah are used. A battery system typically consists of several cells. Usually, up to 10 cells form a module unit, in which they are connected in series or parallel. A battery system, in turn, consists of several modules combined with a cooling and battery control unit. The voltage of a series-connected battery system can reach up to 400 V.

[0006] The substances contained in a lithium-ion battery cell can pose a potential hazard if released uncontrollably. For example, the organic electrolyte mixtures containing ethylene carbonate and dimethyl carbonate are highly flammable, harmful to health, and detrimental to groundwater. The conductive salt LiPF6 readily hydrolyzes to phosphoric acid and hydrogen fluoride (HF). HF, in turn, is corrosive and toxic. It can easily enter the respiratory tract as a gas and thus cause burns. Additionally, the central nervous system is damaged by fluorine's high binding affinity to calcium. Various additives are also classified as toxic.

[0007] For this reason, lithium-ion batteries are classified as hazardous materials. The transport of new batteries by road is only permitted if they have been tested. However, if a lithium-ion battery is defective, current regulations only allow transport with a special permit. Therefore, there is a need for a transport solution for damaged lithium-ion batteries that minimizes the potential risk to people and the environment during transport and unpacking. Such a transport solution is a significant factor for the widespread adoption of electromobility.

[0008] The transport of a battery from an accident site involving an electric vehicle must therefore be clearly regulated. If a defective battery, or a battery in an undefined condition, is being transported, the transport concept must provide the necessary safety measures to mitigate potential hazards. These hazards include, for example, the leakage of gases and liquids from the battery. In particular, transport containers that can withstand the so-called thermal runaway of one or two cells must be developed. During this process, a lithium-ion battery heats up very rapidly, leading to an exponential increase in degradation rates. This can result in an explosive outgassing followed by ignition.

[0009] The transport solutions currently under discussion mostly involve the use of vermiculite, as this layered silicate is capable of absorbing liquids and vapors of polar substances. Often, a mixture with calcium carbonate or calcium chloride is used to bind any potentially escaping HF. When calcium carbonate is used, the fluoride can be trapped by the calcium, while the proton is bound by the basic carbonate.

[0010] DE 10 2012 023 433 A1 describes a receiving device designed for transporting damaged lithium-ion batteries, comprising an inner and an outer container. The damaged battery is placed in the inner container. The inner and outer containers are dimensioned such that there are gaps between the battery and the inner container and between the inner and outer containers, respectively. These gaps contain temperature-resistant and, if necessary, gas-absorbing materials, such as vermiculite and mineral wool. The containers can be made of wood, for example. Furthermore, a gas-impermeable polymeric plastic sleeve is present between the inner and outer containers.

[0011] DE 10 2010 048 051 A1 describes the use of a fiberglass fabric cushion for filling gaps in a transport container for lithium-ion batteries. The fiberglass fabric cushion can be filled with vermiculite granules.

[0012] DE 20 2014 100 119 U1 concerns a transport container for damaged lithium-ion batteries, in which a box is lined with insulating panels. A mixture of sand and vermiculite is proposed as the insulating material. Disclosure of the invention

[0013] One or more problems of the prior art can be solved or at least mitigated by means of the transport container according to the invention for a damaged lithium-ion battery. The transport container comprises a gas-permeable inner housing designed to hold the lithium-ion battery, and an outer housing designed to hold the inner housing and to equalize pressure with the environment. The inner housing and the outer housing are dimensioned such that an inner space exists between the inner housing and the lithium-ion battery, and an outer space exists between the inner housing and the outer housing. The inner and / or outer space contains a filling of an absorbent, thermally stable filling material. This transport container is characterized in that the filling material in the inner and / or outer space contains a zeolite, in particular dealuminized zeolite.

[0014] If a defective or damaged battery begins to outgas, a variety of gases, vapors, and liquids, some of which are hazardous to health and can be highly flammable, are released. In the event of ignition, further harmful combustion gases and compounds are produced. While vermiculite, the filler previously used in transport containers, has a high absorption capacity for various substances, it does not reliably bind nonpolar organic substances. However, if the filler contains zeolite, the absorption of nonpolar gases and vapors can be significantly increased. Dealuminized zeolite, in particular, dramatically improves the absorption of nonpolar substances from a degassing, damaged battery, especially in the event of ignition when combustion gases are also produced. This leads to a significant reduction in the release of harmful substances.

[0015] In particular, the filling material in the inner and / or outer space contains vermiculite. The combination of vermiculite and zeolite makes it possible to bind gases, vapors, or liquids escaping from a defective battery, regardless of their polarity. Preferably, the inner space contains vermiculite but no zeolite, and the outer space contains a mixture of vermiculite and zeolite. This arrangement exhibits particularly favorable absorption behavior at higher temperatures.

[0016] Furthermore, it is preferred if the filling material is contained in cellulose or glass wool bags. Glass wool is particularly preferred due to its very high chemical and thermal stability. This measure allows the filling material to be distributed more evenly in the transport container, and significantly simplifies material replacement.

[0017] According to a further preferred embodiment of the transport container, the inner casing is coated with calcium carbonate or calcium citrate. This impregnation of the inner casing, which is preferably made of wood or plastic to minimize weight, increases its fire resistance. Additionally, the impregnation acts as a further barrier against any HF produced and, if applicable, other acidic combustion gases.

[0018] Furthermore, the inner space can contain a film made of polypropylene or an aluminum composite material, which serves to package the lithium-ion battery. In other words, the battery is packaged with the film for transport. This helps to contain any escaping liquids or gases resulting from a battery leak. However, in the event of thermal runaway, the film becomes sufficiently permeable to allow for rapid pressure equalization and prevent an explosion.

[0019] Finally, it is preferable for the outer casing to have a cladding made of aerated concrete. This prevents excessive heating of the surrounding area in the event of thermal runaway from the battery. Pressure equalization can then be ensured, for example, by means of a suitable lid valve.

[0020] Further preferred embodiments can be found in the dependent claims and the following description. Drawings

[0021] The invention is explained in more detail with reference to an exemplary embodiment and an accompanying drawing. The single drawing shows: Fig. 1 A schematic representation of a transport container according to the invention in a semi-transparent representation. embodiment of the invention

[0022] Fig.Figure 1 shows a model of a possible embodiment of a transport container 10 according to the invention for holding a damaged lithium-ion battery 12 in a semi-transparent representation. The transport container 10 comprises an inner housing 14 made of, for example, wood or plastic, wherein the inner housing 14 does not seal the interior airtight but is rather gas-permeable such that rapid pressure equalization is possible. The inner housing 14 is impregnated with calcium carbonate or calcium citrate to improve fire resistance. At the same time, the impregnation can act as an RF barrier. For transport, the battery 12 is wrapped with a polypropylene or aluminum composite film 18.

[0023] The inner housing 14 is in turn housed in an outer housing 16. The outer housing 16 can be made of metal or wood, for example, and is designed to allow pressure equalization at all times, for example by means of valves (not shown) or predetermined breaking points in the lid area or on the sides of the outer housing 16. Otherwise, the transport container 10 would become a hazard simply due to a pressure increase during degassing. In the event that the transport container 10 is exposed to thermal transfer from the battery 12, a significant temperature increase will occur. To minimize the heating of the surroundings in such a potential incident, it is also conceivable to add a layer of lightweight aerated concrete (not shown) to the outer housing 16 to increase thermal insulation. Even with this design, pressure equalization must be possible, for example by means of a suitable lid valve.

[0024] The inner casing 14 is dimensioned such that sufficient internal space remains between it and the battery 12. This internal space contains a filling material, shown here schematically as a filled glass wool bag 20. The filling material for the internal space is vermiculite and may optionally be mixed with calcium carbonate or calcium citrate.

[0025] An external space formed between the inner casing 14 and the outer casing 16 contains another glass wool bag 22, which is filled with a 1:1 mixture of vermiculite and a dealuminized zeolite. The amount of zeolite and vermiculite used in the glass wool bags 20, 22 should be such that at least 1.5 times the amount of electrolyte contained in the battery 12 can be bound.

Claims

[1] Transport container (10) for a damaged lithium-ion battery (12), comprising a gas-permeable inner casing (14) designed to accommodate the lithium-ion battery (12), and an outer casing (16) designed to accommodate the inner casing (14) and to equalize pressure with the environment, wherein the inner casing (14) and the outer casing (16) are dimensioned to provide an inner space between the inner casing (14) and the lithium-ion battery (12) and an outer space between the inner casing (14) and the outer casing (16), and wherein the inner and / or outer space contains a filling of an absorbent, thermally stable filling material, characterized by that the filling material in the inner and / or outer space contains a zeolite. [2] Transport container according to claim 1, wherein the zeolite is a dealuminized zeolite. [3] Transport container according to claim 1 or 2, wherein the filling material in the inner and / or outer space contains vermiculite. [4] Transport container according to claim 3, wherein the inner space contains vermiculite but no zeolite and the outer space contains a mixture of vermiculite and zeolite. [5] Transport container according to one of the preceding claims, wherein the filling material is contained in cellulose or glass wool bags (20, 22). [6] Transport container according to one of the preceding claims, wherein the inner casing is coated with calcium carbonate or calcium citrate. [7] Transport container according to one of the preceding claims, wherein the inner space contains a film (18) made of polypropylene or an aluminium composite material, which serves to package the lithium-ion battery (12). [8] Transport container according to one of the preceding claims, wherein the outer casing (16) has a lining made of aerated concrete. [9] Transport container according to one of the preceding claims, wherein the inner housing (14) is made of wood or plastic.

Images