A sustainable and low-cost alternative within Li-ion battery technology

Use of sustainable electrode components in Li-ion battery technology is essential for large-scale applications while addressing environmental concerns.  Considering elemental abundance, Fe-based compounds can, in principle, work as the most economic cathodes.  Fe-based hydroxysulfates Li_xFeSO₄OhH (_x-0 -1) can be harnessed as low-cost, sustainable, high-voltage, and moisture-resistant battery cathode materials.

In this system, monoclinic (m) FeSO₄OH and layered m-FeSO₄OH were previously reported as Li-ion battery cathode materials.  In the paper 'Alternative Polymorph of the Hydroxysulfate Li_xFeSo₄OH Yields Improved Lithion-Ion Cathodes' (published in Chemistry of Materials), the authors introduce orthorhombin (0) FeSO₄OH as a potential low-cost cathode for Li-ion batteries synthesised by using a facile low-temperature hydrothermal route.  The o-FeSO₄OH cathode delivers a reversible capacity of 100 mA h/g at a current rate of C/20 (1e^-=159 mAh/g) at a working potential of ca.3.2 V vs Li⁺/Li.  A higher overpotential and faster rate kinetics compared with that of m-FeSO₄OH stem from the subtle deviations in the structural framework affecting the Li coordination environment.  Operando analytical tools, electrochemical titration techniques, and computational modelling are combined to characterise the complex phase transformation during the (de)lithiation process.