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4 V All-Solid-State Battery Enabled by a Passivating Cathode/hydroborate Solid Electrolyte Interface
Corsin Battaglia1,Ryo Asakura1,David Reber1,Léo Duchêne1,Seyedhosein Payandeh1,Arndt Remhof1
Empa–Swiss Federal Laboratories for Materials Science and Technology1
Show Abstract
Designing solid electrolytes for all-solid-state-batteries that can withstand the extreme elec-trochemical conditions in contact with an alkali metal anode and a high-voltage cathode is challenging, especially when the battery is cycled beyond 4 V. Here we demonstrate that a hydroborate solid electrolyte Na4(CB11H12)2(B12H12), built from two types of cage-like anions with different oxidative stability, can effectively passivate the interface to a 4 V-class cathode and prevent impedance growth during cycling. We show that [B12H12]2− anions decompose below 4.2 V vs Na+/Na to form a passivating interphase layer, while [CB11H12]− anions remain intact, providing sufficient ionic conductivity across the layer. Our interface engineering strategy enables the first demonstration of a 4 V-class hydroborate-based all-solid-state battery combining a sodium metal anode and a cobalt-free Na3(VOPO4)2F cathode without any artificial protective coating. When cycled to 4.15 V vs Na+/Na, the cells feature a discharge capacity of 104 mAh g−1 at C/10 and 99 mAh g−1 at C/5, and an excellent capacity and energy retention of 78% and 76%, respectively, after 800 cycles at C/5 at <0.2 MPa at room temperature. Increasing the pressure to 3.2 MPa enables a discharge capacity of 117 mAh g−1 at C/10 with a mass loading of 8.0 mg cm−2, corresponding to an areal capacity close to 1.0 mAh cm−2. The cell holds the highest average discharge cell voltage of 3.8 V and specific energy per cathode active material weight among all-solid-state sodium batteries reported so far. Combined with their low gravimetric density <1.2 g/cm3, low toxicity, high thermal and chemical stability [2], stability vs lithium and sodium metal anodes [3], soft mechanical properties enabling cold pressing [4], compatibility with solution impregnation [5] and infiltration [6], and potential for low cost [7, 8], hydroborate electrolytes represent a promising option for a competitive future all-solid-state battery technology.
References:
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[2] R. Asakura, L. Duchêne, R.-S. Kühnel, A. Remhof, C. Battaglia, ACS Appl. Energy Mater. 2019, 2, 6924
[3] L. Duchêne, R.-S. Kühnel, D. Rentsch, A. Remhof, H. Hagemann, C. Battaglia, Chem. Comm. 2017, 53, 4195
[4] L. Duchêne, A. Remhof, H. Hagemann, C. Battaglia, Energy Storage Mater. 2020, 25, 782
[5] L. Duchêne, R.-S. Kühnel, E. Stilp, E. Cuervo Reyes, A. Remhof, H. Hagemann, C. Battaglia, Energy Environ. Science 2017, 10, 2609
[6] L. Duchêne, D. H. Kim, Y. B. Song, S. Jun, R. Moury, A. Remhof, H. Hagemann, Y. S. Jung, C. Battaglia, Energy Storage Mater., 2020, 26, 543
[7] A. Gigante, L. Duchêne, R. Moury, M. Pupier, A. Remhof, H. Hagemann, ChemSusChem 2019, 12, 4832
[8] S. Payandeh, R. Asakura, P. Avramidou, D. Rentsch, Z. Lodziana, R. Cerny, A. Remhof, C. Battaglia, Chem. Mater. 2020, 32, 1101