An operando X-ray diffraction study of chloroaluminate anion-graphite intercalation in aluminum batteries.

Pan, Chun-Jern; Yuan, Chunze; Zhu, Guanzhou; Zhang, Qian; Huang, Chen-Jui; Lin, Meng-Chang; Angell, Michael; Hwang, Bing-Joe et al. · Proc Natl Acad Sci U S A · 2018

basic_science · Level V

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Abstract

We investigated rechargeable aluminum (Al) batteries composed of an Al negative electrode, a graphite positive electrode, and an ionic liquid (IL) electrolyte at temperatures down to -40 °C. The reversible battery discharge capacity at low temperatures could be superior to that at room temperature. In situ/operando electrochemical and synchrotron X-ray diffraction experiments combined with theoretical modeling revealed stable AlCl<sub>4</sub><sup>-</sup>/graphite intercalation up to stage 3 at low temperatures, whereas intercalation was reversible up to stage 4 at room temperature (RT). The higher-degree anion/graphite intercalation at low temperatures affords rechargeable Al battery with higher discharge voltage (up to 2.5 V, a record for Al battery) and energy density. A remarkable cycle life of >20,000 cycles at a rate of 6C (10 minutes charge time) was achievable for Al battery operating at low temperatures, corresponding to a >50-year battery life if charged/discharged once daily.