成果報告書詳細
管理番号20160000000436
タイトル*平成27年度中間年報 リチウムイオン電池応用・実用化先端技術開発事業 研究開発項目(3)車載用リチウムイオン電池の試験評価法の開発
公開日2016/6/25
報告書年度2015 - 2015
委託先名一般財団法人日本自動車研究所
プロジェクト番号P12003
部署名スマートコミュニティ部
和文要約
英文要約Market interest is increasing the safety of lithium ion batteries (“LIB”, the current mainstay of in-vehicle batteries) while at the same time it is essential to ensure satisfactory battery performance against the decline of battery capacity due to the service life. For the widespread use of LIBs, growing importance is placed on the R&D and standardization of platform methodologies for evaluating the safety and life performances of LIBs. As these issues include the agenda of the EVS-IWG (on safety) and EVE-IWG (on environment) of the United Nations (UN) forum, it is necessary that Japan lead the UN discussions for the international harmonization of LIB evaluation methodologies.
In the “technology development project for the application and commercialization of lithium ion batteries” which had been undertaken by NEDO, technology development of next-generation LIBs which are high-performance compared to existing automotive LIBs has been conducted. NEDO believe the development of next-generation LIBs will be encouraged by impartial evaluation and indication for the clarifying advantages  and weak points of new LIB prototypes to their developers. However, such an evaluation method is not exist at present. It is needed to collect experimental findings for the development of new LIBs as well as for the consideration of an international standard or regulation test procedure for LIBs.
Accordingly, JARI and AIST jointly undertook the study to develop a safety testing method and investigate the existing life testing method for in-vehicle LIBs.
(1) Development for a safety testing method
Firstly, we examined a possible substitution testing method for the published IEC standard on single-cell forced internal short circuit tests with a nickel piece inserted in the cell. Five types of cells which have different shapes and dimensions were subjected to a nail penetration and a blunt rod test under various conditions, and the test results were compared with available data from the forced internal short circuit testing. The results indicated a low capability of the blunt rod testing to substitute for the forced internal short circuit testing.
Secondly, we investigated the creation of internal short circuit starting points for their application to the ISO thermal chain reaction test procedure, using three types of test cells which have different shapes and dimensions. The cells were forced into a thermal runway by overcharging, nail penetration or a heater; then the resultant phenomena and heat generation of the cells were measured. Based on the obtained test results, we proposed a outline draft of LIB safety testing method to the Japanese governmental working group assigned to the formulation of a UN EVS-gtr.
(2) Investigation for the LIB pack life testing method
In the second half of the study, we examined possibilities of substituting battery pack with a single cell for the published ISO life testing method. Three models of electric vehicles available from the market underwent driving tests on a chassis dynamometer in which temperature and cell voltage distributions inside the battery pack were measured. In order to evaluate the effects of the testing method and measured cell distributions on cell degradation, the battery packs were removed from the test electric vehicles and dismantled into modules and cells which were subjected to life tests under varied conditions. To compare the cell condition before and after the degradation test, the pre-test condition of the cells were examined through AC impedance measurement, differential curve analysis on OCV curves, SEM observation of electrode structure, X-ray photoelectron spectroscopy of electrodes, nuclear magnetic resonance spectrometry of electrode-electrolyte interfacial products, etc.
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