Differentiate coulombic efficiency and energy efficiency in rechargeable batteries.

• A. Coulombic efficiency measures energy delivered divided by energy stored; energy efficiency is total charge out divided by total charge in.
• B. Coulombic efficiency is total charge out divided by total charge in; energy efficiency is energy delivered divided by energy stored.
• C. Coulombic efficiency accounts for voltage differences; energy efficiency does not.
• D. Coulombic efficiency is the ratio of current to voltage.

Answer: (B)