Controlling the Voltage Window for Improved Cycling Performance of SnO₂ as Anode Material for Lithium-Ion Batteries.

Transition metal oxide materials with high theoretical capacities have been studied as substitutes for commercial graphite in lithiumion batteries. Among these, SnO₂ is a promising alloying reaction-based anode material. However, the problem of rapid capacity fading in SnO₂ due to volume variation during the alloying/dealloying processes must be solved. The lithiation of SnO₂ results in the formation of a Li₂O matrix. Herein, the volume variation of SnO₂ was suppressed by controlling the voltage window to 1 V to prevent the delithiation reaction between Li₂O and Sn. Using this strategy the unreacted Li₂O matrix was enriched with metallic Sn particles, thereby providing a pathway for lithium ions. The specific capacity decay in the voltage window of 0.05-3 V was 1.8% per cycle. However, the specific capacity decay was improved to 0.04% per cycle after the voltage window was restricted (in the range of 0.05-1 V). This strategy resulted in a specific capacity of 374.7 mAh g at 0.1 C after 40 cycles for the SnO₂ anode.