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Description
David Mitlin1 Jia Ding2

1, Clarkson University, Potsdam, New York, United States
2, State University of New York, Binghamton, Binghamton, New York, United States

Energy density (energy per volume) is a key consideration for portable, automotive and stationary battery applications. We created selenium (Se) lithium and sodium metal cathodes that are monolithic and free-standing, and with record Se loading of 70 wt%. The carbon host is derived from nanocellulose, an abundant and sustainable forestry product. The composite is extremely dense (2.37 g cm-3), enabling theoretical volumetric capacity of 1120 mAh cm-3. Such architecture is fully distinct from previous Se – carbon nano or micropowders, intrinsically offering up to 2X higher energy density. For Li storage, the cathode delivered reversible capacity of 1028 mAh cm-3 (620 mAh g-1) and 82% retention over 300 cycles. For Na storage 848 mAh cm-3 (511 mAh g-1) was obtained with 98% retention after 150 cycles. The electrodes yield superb volumetric energy densities, being 1727 Wh L-1 for Li-Se and 980 Wh L-1 for Na-Se normalized by total composite mass and volume. Despite the low surface area, over 60% capacity is maintained as the current density is increased from 0.1 to 2 C (30 min charge) with Li or Na. Remarkably, the electrochemical kinetics with Li and Na are comparable, including the transition from interfacial to diffusional control.

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