ࡱ > bjbj k e e 6 d Z Z g g g g g h h h 8 :h i 4 h / :k :k ( bk bk bk bu bu bu ~ $ t E g bu Lt @u " bu bu g g bk bk v v v bu g bk g bk ~ v bu ~ v v N bk 0lw u Ҫ F j 0 / ; v ; T : T ; g ! bu bu v bu bu bu bu bu v bu bu bu / bu bu bu bu ; bu bu bu bu bu bu bu bu bu Z f : UN/SCETDG/47/INF.13/Rev.1Committee of Experts on the Transport of Dangerous Goodsand on the Globally Harmonized System of Classificationand Labelling of Chemicals Sub-Committee of Experts on the Transport of Dangerous Goods 12 June 2015 Forty-seventh session Geneva, 22 June-26 June 2015 Item 4 (a) of the provisional agenda Electric storage system: testing of lithium batteries New proper shipping name for rechargeable lithium metal batteries Transmitted by the expert from the Republic of Korea Introduction 1. Rechargeable lithium metal batteries (RLMBs) have been developed and commercialized for many years but remain a very small segment of the lithium battery market. However, due to improvements in the technology, the applications and use of RLMBs are expected to increase substantially over the next 5 to 10 years. Therefore, the UN Sub-Committee is invited to consider changes to the UN Model Regulations to accommodate these batteries as discussed in more detail below. 2. A RLMB utilizes lithium metal in the anode of a cell instead of graphite, which is typically how lithium ion batteries are designed. The demand is largely driven by requests for higher energy density than that provided by the current lithium ion batteries. Up to now, the lithium ion battery technology is reaching its theoretical limit with a combination of all available technologies including cell components, designs, production and circuits. (Fig1) Like lithium ion batteries, RLMBs can be widely used to power electrical devices like hand held phones, power tools, electric vehicles and energy storage systems. Consequently, new proper shipping names and amendments to existing special provisions for transporting RLMBs are necessary to address the growing demand for shipping RLMBs. Background information on lithium batteries Definition of a RLMB 3. A RLMB is a rechargeable electrochemical device in which charge and discharge can be repeated by plating or stripping lithium ions at the negative electrode, and by intercalating and deintercalating lithium ions, or alloying reaction of lithium ions at the positive electrode, depending on the chemistry of the positive active materials. The negative electrode is comprised of lithium metal with a specially designed, protective layer leading to uniform plating and stripping reactions on the lithium surfaces. Depending on the chemistry, the positive electrode can be comprised of an oxide, sulfur composite or other material. The electrolyte used in RLMB is a non-flammable, partial solid. Constituent of a RLMB and operating principle 4. A RLMB cell is comprised of a negative electrode, positive electrode, separator and electrolyte. (Fig.2) A RLMB is a rechargeable lithium metal battery which can store the electrical energy by plating and stripping lithium ions at the negative electrode, and by intercalating and deintercalating lithium ions at the positive electrode in the case of oxides (Fig.3), or alloying and dealloying lithium ions in the case of sulfur composites. (Fig.4) 5. As for a RLMB, the anode electrode is comprised of lithium metal and a protective layer, in place of graphite as typically found in lithium ions batteries. In the case of graphite, its principle is based on the intercalating and deintercalation chemistry. On the other hand, in the case of lithium metal, the principle is based on the plating and stripping chemistry. Unlike graphite, no housing for lithium ions exists in lithium metal. Therefore, electricity is stored at the negative electrode by lithium plating. Since there is no boundary for the plating, non-uniform growth of lithium ions (i.e., dendrites) could appear at the negative electrode, which could cause safety concerns. (Fig.5) For this reason, the protective layer, an ultra thin polymer matrix including various additives like salts, nanopowders and other proprietary materials, is needed. Features of RLMBs (comparison with lithium ions batteries) 6. A RLMB has the following features compared to lithium ion batteries: (Table 1) (a) The chemistry of lithium metal is plating and stripping whereas that of graphite it is intercalating and deintercalating. (b) The gravimetric charge density of lithium metal is 10.4 times higher than that of graphite: Lithium 3,862mAh/g vs. Graphite 372 mAh/g. (c) The volumetric charge density of lithium metal is about 2.4 times higher than that of graphite: Lithium 2,047 mAh/cm3 vs. 837mAh/cm3. (d) The potential of lithium metal vs. lithium is zero whereas that of graphite it is 0.05V. This difference can be transferred to an increase in capacity. (e) A large volumetric change appears from lithium metal, compared to that of graphite. (f) Because lithium metal can be more reactive than lithiated graphite, these safety concerns must be addressed through proper cell and battery design and testing. Applications of RLMBs 7. A RLMB can be applied to all devices in which current lithium ions batteries are being used. A system of lithium metal/LiCoO2 is 1.64 times higher in gravimetric energy density than that of graphite/LiCoO2, when the active-only energy density is calculated. See Table 2 and Fig 6: Li/LiCoO2 998Wh/kg vs. Graphite/LiCoO2 607Wh/kg. 8. A RLMB is quite suitable for applications which require higher energy density, high power density and low cost. Potential applications for a RLMB are as follows: (a) Small-sized, portable devices like smart watches, hand-held phones, tablets, NPC; (b) Medium-sized devices like power tools, e-bikes; and (c) Large-sized devices like electric vehicles and energy storage systems. History of transport regulations for lithium batteries (Table 3) 9. Reviewing the history of international transport regulations for Li batteries since 2001, three significant changes occurred. The first change occurred in 2003. Medium-sized cells (1g