Engineering topics

Yang, Dandan

Publications and source records attributed to Yang, Dandan.

3 records

DOE OSTI2021

Glass-fiber-reinforced polymeric film as an efficient protecting layer for stable Li metal electrodes

With numerous reports on protecting films for stable lithium (Li) metal electrodes, the key attributes for how to construct these efficient layers have rarely been fully investigated. Here, we report a rationally designed hybrid protective layer (HPL) with each component aligning with one key attribute; i.e., cross-linked poly(dimethylsiloxane) (PDMS) enhances flexibility, polyethylene glycol (PEG) provides homogeneous ion-conducting channels, and glass fiber (GF) affords mechanical robustness. A significant improvement of the electrochemical performance of HPL-modified electrodes can be achieved in Li/HPL@Cu half cells, HPL@Li/HPL@Li symmetric cells, and HPL@Li/LiFePO 4 full cells. Even with an industrial standard LiFePO 4 cathode (96.8 wt % active material), the assembled cell still exhibits a capacity retention of 90% after 100 cycles at 1 C. More importantly, the functionality of each component has been studied comprehensively via electrochemical and physical experiments and simulations, which will provide useful guidance on how to construct efficient protective layers for next-generation energy storage devices.

25 ENERGY STORAGE↗

DOE OSTI2020

Ultra-efficient polymer binder for silicon anode in high-capacity lithium-ion batteries

As a highly promising anode material for high-capacity lithium-ion batteries (LIBs), the low electronic conductivity and large volume variation of silicon (Si) make the slurry-coating Si based electrode requiring high content of “inert” materials and suffering rapid capacity fading. In this work, a polyimine, synthesized via one-step condensation reaction, has been demonstrated as an ultra-efficient polymer binder that can resolve the above issues. The polyimine binder containing Si electrode delivers superior electrochemical performance: a delithiation specific capacity of 804.4 mAh g –1 with capacity retention of 82.4% after 1000 cycles at the current density of 2 A g –1 . The high efficiency of polyimine binder for Si electrode has also been demonstrated with ultrahigh weight ratio of “active” material to “inert” material (R A/I ). The electrode with 95 wt% of Si (95Si/Polyimine, R A/I = 19) reveals a reversible delithiation capacity of 2114 mAh g –1 (capacity retention ~ 80.4%) over 200 cycles at the current density of 400 mA g –1 . Even at the high current density of 2 A g –1 , a delithiation capacity of 1087.8 mAh g –1 after 500 cycles can be obtained. Molecular simulations and atomic force microscopy (AFM) indentation are utilized to investigate the ultra-efficiency of polyimine binder. With simple manufacturing process and ultra-efficient binder performance, the designed polyimine binder will be definitely meaningful in achieving low-cost and high-capacity LIBs with prolonged cycle life.

25 ENERGY STORAGE↗

DOE OSTI2019

From natural material to high-performance silicon based anode: Towards cost-efficient silicon based electrodes in high-performance Li-ion batteries

As one of the highest specific capacity anode materials in lithium-ion batteries, the main technical issue for silicon (Si) based electrodes is the rapid capacity fading caused by the huge volume changes. Porous Si materials are reported to efficiently alleviate the side effects of volume fluctuation. However, the expensive precursor and complicated production process in previous reports limited their practical applications. Herein, we report a cost-efficient approach on the fabrication of porous Si via the low temperature aluminothermic reduction of low cost natural raw materials, combining the advantages of low temperature and natural materials. The porous structure of attapulgite-derived Si (Si ATP ) is well retained during the compositing process. The obtained composite electrode Si ATP /graphite@carbon (Si ATP /G@C) exhibits excellent electrochemical performance, with a reversible discharge capacity of 799 mAh g -1 after 100 cycles. To demonstrate the versatility of the approach, another natural ore, mica (MIC), was also utilized to the fabrication of porous Si (SiMIC). As expected, the SiMIC/graphite@carbon composite electrode also exhibits high specific capacity (697 mAh g -1 after 100 cycles), superior capacity retention (81% after 100 cycles based the 4th cycle), and outstanding rate capability.

25 ENERGY STORAGE↗