The correct statement about the lithium-ion battery is:
The mass of the battery increases when it is recharged.
When a lithium-ion battery is recharged, lithium ions move back to the anode from the cathode, leading to changes in charge but not in mass. However, over many cycles, one can argue that there is very negligible mass loss due to chemical reactions and gas emissions, but typically the mass remains essentially constant because of the conservation of mass principle in closed systems.
The other statements are incorrect:
- Electrons are not lost to the environment; they flow through the external circuit.
- No new substances are formed; the same lithium compounds are cycled during charging and discharging.
- Lithium atoms are not created; the existing lithium is simply moved between electrodes during the charging process.
Overall, though the mass may seem to change to a very small degree under different conditions, the most straightforward answer from a conceptual standpoint based purely on recharge mechanics is that it stays roughly the same.