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Electrochemical quartz crystal microbalance measurements of the electrode reactions in lithium secondary batteries

锂二次电池电极反应的电化学石英晶体微天平测量

基本信息

批准号：
19K15682
负责人：
芹澤信幸
金额：
$ 2.66万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Early-Career Scientists
财政年份：
2019
资助国家：
日本
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

项目摘要

リチウム二次電池の充放電効率向上，劣化機構の解明や高速充放電の実現には充放電に伴う電極質量変化や電極近傍におけるリチウムイオンの輸送現象の観測が効果的である．本研究では，ナノグラムオーダーの電極質量変化と電解液の濃度分布を反映した局所的な電解液物性（粘性率と密度）の変化を高感度かつその場（in-situ）観測できる電気化学水晶振動子マイクロバランス（EQCM）法を二次電池の電極反応に適用する．塗布電極の作製やセパレーター存在下での測定を通じて，実電池内部を模擬した環境での二次電池の詳細反応解析を試みる．第四年度にあたる令和4年度は令和2年度までに作製手法を確立した低抵抗な合剤塗布電極を用いてEQCM法による充放電反応解析を進めた．カーボネート系電解液中でのチタン酸リチウムの充放電反応について，電解液の局所物性を反映する共振抵抗変化に対する合剤塗布量，充放電速度および電解液対流の影響を調べることで，観測される共振抵抗変化は合剤電極内部に含まれる電解液中の平均リチウム塩濃度を主に反映することを明らかにした．さらに，特に充放電速度が速い場合，充放電に伴う電極質量変化を観測される共振周波数変化から直接見積もると通電電気量から見積られる計算値との差が大きかったが，前述の電解液の局所物性変化の寄与を差し引くことで計算値と一致し，充放電および休止中における合剤電極質量の変化を定量的に解析することに成功した．

The charging efficiency of secondary batteries is increasing, the degradation mechanism is solved, the high speed charging is realized, the charging is reversed, the electrode quality is changed, the electrode is near, the transport phenomenon is measured, and the results are obtained. In this study, the electrochemistry crystal oscillator method (EQCM) is applied to the electrode reaction of secondary batteries by reflecting the electrode mass change and electrolyte concentration distribution of the electrode mass change and the electrolyte physical properties (viscosity and density) change with high sensitivity and in-situ measurement. The coating electrode is fabricated and tested in the presence of a coating material, and the battery interior is simulated and the environment is analyzed in detail. In the fourth and fourth years, the method of operation was established, and the electrode was coated with EQCM method. The resonance resistance of the electrolyte in the electrolyte system is reflected by the charge reaction of the electrolyte, the coating amount of the electrolyte, the charge rate and the influence of the electrolyte on the current. The resonance resistance of the electrolyte system is mainly reflected by the average charge concentration of the electrolyte contained in the interior of the electrolyte. In particular, when the charging speed is high, the difference between the calculated value and the calculated value of the change in the mass of the electrolyte is large, and the difference between the calculated value and the calculated value of the change in the mass of the electrode is large.