(358d) Reserve Lithium-Ion Batteries for Lithium-Ion Free Cathodes

Lithium-ion Batteries’ (LIBs) influence on every aspect of human lives has been unimaginable. One sector, which has received a tremendous boost because of LIBs is transportation. Electric vehicle (EV) sales have increased almost 20 folds from 2011 until now. This has caused a huge increase in the demand for LIBs across the world. Presently, there is heavy dependence on cathodes like LiFePO₄, LiNiO₂, LiCoO₂, and LiNi_xMn_yCo_zO₂ to meet energy expectations. Compounds without lithium in their lattice rarely have been used as cathodes either due to inability for reverse reactions or require lithium electrode, which causes lithium dendrites on continuous cycling. This has resulted in fewer efforts towards the development of such lithium-free cathodes. Some of these materials are ZnO, TiO₂, Cr₃O₄, MnO₂, V₂O₅, etc. Although these materials possess high theoretical capacities, many of them have a low potential for faradic reactions and have the risk of reducing to metal states during the electrochemical reactions. Hence, for such materials to commercialize, few measures have been taken namely, pre-lithiation of the cathode, film-forming additives, lithium additives, blended cathodes, etc. Some strategies like pre-lithiation are not practical and feasible, even though they help in overcoming solid electrolyte layer interface (SEI). Other strategies alter the cell voltage characteristics due to the presence of voids in the electrode.

We present a pioneering configuration called reserve lithium-ion batteries for in situ lithiation of the lithium-free electrodes with the use of lithium-electrode as a reservoir. For the initial formation of the SEI and lithiation of the MCMB electrode, a reservoir lithium electrode was brought into the cell circuitry. V₂O₅ cathode with meso carbon microbeads (MCMB) was used to fabricate high specific capacity and energy-dense reserved lithium-ion batteries (RLIBs). The RLIB system delivered a high charge specific capacity of 245 mAh g^-1 at 0.2C rate. The tri-electrode system provided an initial high energy density of >880 Wh kg^-1. A parallel comparison of electrochemical performance between V₂O₅ half-cell, V₂O₅-MCMB full-cell, and V₂O₅-MCMB RLIB was conducted and observed. There is a distinct resemblance in the performance of RLIB performance with half-cell profile and in terms of capacity versus cycle number. The pouch-cell configurations of this work yielded a high energy-dense system, which cycled stably over more than 200 cycles at 0.5C rate. Using this innovative concept of reservoir charging would be of great importance for applications in various sectors of the society viz., space exploration, UPS, healthcare, EVs, grid storage, etc.