Electrolyte design for lithium-ion batteries with a cobalt-free cathode and silicon oxide anode

Lithium-ion batteries (LIBs) to power electric vehicles play an increasingly important role in the transition to a carbon neutral transportation system. However, at present the chemistry of LIBs requires, among other elements, cobalt (Co), which will probably become scarce over time in addition to posing supply chain risks related to its single source, human rights and mining practices. To address this problem, we construct a LIB pairing a Co-free cathode with a silicon suboxide (SiOx) anode that possesses a high cut-off voltage of 4.9 V and sustains unprecedented 1,000 cycles. Underlying this favourable electrode combination is a rational electrolyte design based on 3.4 M LiFSI/FEMC featuring a shifted potential, which serves to aid formation of robust passivation layers on the anode and promote electrolyte stability against both reductive and oxidative degradations. Our electrolyte formulation offers a pathway towards both sustainable and high-performing LIBs, while the concept could be applied to other electrochemical energy technologies.