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成果報告書詳細
管理番号20170000000236
タイトル*平成28年度中間年報 革新型蓄電池実用化促進基盤技術開発(学校法人関西大学)
公開日2017/11/14
報告書年度2016 - 2016
委託先名学校法人関西大学
プロジェクト番号P16001
部署名スマートコミュニティ部
和文要約
英文要約Title: Research and Development Initiative for Scientific Innovation of New Generation Batteries 2 (RISING2) (FY2016-FY2018) FY2016 Annual Report, Kansai University, Japan
Our (prof. Ishikawa's) group in Kansai Univ. has been devoted to the subject: "Improvement in reaction efficiency and cycleability of conversion cathode by novel binder" in the nanomaterial interface-controlled battery team in the cation migration-type battery group; the present results are as follows:
(1) Search of natural binder compatible to nano-sized conversion cathode material.
We have searched binder compatible to Iron(III) fluoride (FeF3) that undergoes intercalation and conversion mechanisms. Polyvinylidene difluoride (PVdF) has so far been used as binder for FeF3. However, nano-sizing of FeF3 as well as a large amount of conductive auxiliary compensating FeF3's poor conductivity requires high dispersion ability of binder in the slurry precursor. Thus, we searched alternative binder more favorable to such a FeF3 system. We have eventually found a natural polymer for a nonaqueous binder system; the novel natural binder is soluble in NMP, and the binder was found to provide a uniform electrode film on aluminum-foil current collector in a ratio of 95 to 5 (w/w) as FeF3 to the binder.
Next, we tried to improve the quality of electrode film containing FeF3 to realize charge-discharge operation as well as to get a relatively thick electrode film. We introduced ball-milled FeF3 with acetylene black (AB) from AIST Kansai center to improve the electrode film's quality. The obtained slurry containing the FeF3 particles and our binder with a ratio of 95 to 5 showed a very high solid component concentration that was 40%, although the highest solid component concentration in conventional PVdF-based FeF3 slurry was 20%. Such a high solid component concentration should be promising to prepare high mass-loading or thick electrode.
(2) Performance of the present electrode utilizing our natural binder.
The present binder electrode exhibited slightly higher capacity retention compared to the PVdF-based electrode. Furthermore, our binder electrode showed much higher mechanical strength (almost twice) than the PVdF-based electrode when they were tested by an exfoliation strength experiment apparatus. In particular, even when the present natural binder was soaked in a HF solution before slurry preparation, the electrode made from the HF-treated binder showed the same strength as the corresponding electrode without the HF treatment. These results clearly suggest that the present binder should have resistibility against volumetric change of the active material during cycling and durability against attack by fluorine species.
Next year, we will try to make an improved electrode as thick as possible to increase in its energy density, and carry out longer cycling test focusing on long-term durability.
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