In Operando Lithiation of Lithium Free Cathodes

Abstract

Lithium and lithium-rich containing cathodes such as LiCoO2, LiFePO4, LiNixMnyCozO2, Li-rich anti-fluorite Li5FeO4 have dominated the portable battery energy storage market. Compounds without lithium in their lattice seldomly have been used as positive electrodes either due to incapability for reversible reactions or require metallic lithium metal electrode. These limitations have prevented the development of new positive electrodes to a larger extent in lithium-ion batteries. Examples of such materials are sulfur, vanadium oxides, FeS2, MnO2, FeF3, etc. However, these materials demonstrate tremendously high specific capacities, and high operating voltages, possibly realizing advanced next-generation batteries. To practically realize them, it is pertinent to address the lithiation strategies, namely pre-lithiation of the anode,blended cathodes, lithium additives, and film-forming additives. These methods result in modification of cell voltage on account of Li+ ion voids in the cathode, whereas pre-lithiation of anode compensates initial lithium consumption. Nevertheless, the pre-lithiation process is one of the unique techniques connected with the complicated, multistep, moisture-sensitive, expensive process, which is not feasible in large-scale applications.In situ lithiation of cathode or anode electrodes for the development of longer-lasting rechargeable batteries uses metallic lithium-electrode as a booster and reservoir. The presence of third reservoir electrode in the lithium-ion battery (LIB), i.e., metallic lithium, is brought into electrochemical reactions initially during the lithiation process and later as a booster to rejuvenise LIBs after the capacity fade on account of cycling. Here, we report the usage of V2O5 cathode with tailored silicon-carbon-graphite composite to fabricate high specific capacity and high energy-density LIBs. The tri-electrode system delivered a high initial charge specific capacity of 240 mAh g-1. After 100 cycles, re-boosting was provided, and at the end of 200th cycle the cell delivered a high average capacity of 140 mAh g-1. The tri-electrode system provided an initial high energy density of 960 Wh kg-1 and an average of 560 Wh kg-1 after 200 cycles. Using thermal signatures from multiple module calorimetry, the safety features of the proposed tri-electrode system were studied and compared to conventional LIBs. Using this novel concept of reservoir boosting would be of prime importance and value in space, healthcare, electric vehicles, UPS, grid-storage, etc. applications.