Abstract: Systems and control devices for charging and discharging a lithium-ion battery and relevant methods are provided. A variable frequency triggering oscillation charge-discharge device constructs an oscillation loop with a lithium-ion battery using an inherent impedance characteristic of the lithium-ion battery to charge and/or discharge the lithium-ion battery in the form of an oscillation current generated by the oscillation loop, to avoid direct current (DC) charge-discharge for the lithium-ion battery or battery pack that causes polarization and lithium precipitation of the lithium. Accordingly, the lithium-ion battery has longer battery life, higher charging threshold voltage, higher charge, and controlled internal temperature increase. Thus, the suitable temperature range for the lithium-ion battery is broadened.