When a lithium-ion battery is used and subsequently recharged, the following statement is correct: A new substance is formed as the battery is used.
During the discharging process (when the battery is being used to power devices), lithium ions move from the anode to the cathode, allowing the battery to provide electrical energy. During recharging, lithium ions move back to the anode.
However, it's important to note that while new lithium compounds and states form during the cycle, the battery overall remains the same lithium-ion chemistry. Therefore, while new electrochemical states are created, it’s not accurate to say a completely new substance is formed directly as in chemical reactions; rather, it describes the reversible conversion of materials within the battery.
The other statements you provided are incorrect:
- The mass of the battery does not increase when it is recharged; it remains effectively constant overall, as mass is conserved in the system.
- Lithium atoms are not created during recharging; instead, they are transferred back and forth between the anode and cathode.
In summary, while the processes in the battery create different chemical states during discharge and recharge, they do not create new substances as defined in a strict chemical sense, nor do they result in a net mass change or generation of lithium atoms.