Secondary battery, secondary battery module, power storage system, and method for operating thereof
View Patent ↗Degradation of a secondary battery or the like is prevented. A reduction in the capacity of a secondary battery or the like due to charging or discharging is prevented. A secondary battery module in which a secondary battery can be charged in a charging period into which short discharging periods are inserted is provided. A secondary battery module in which a plurality of secondary batteries are connected in parallel, and in a charging period of the secondary batteries, current due to short-time discharging of one secondary battery can be used for charging another secondary battery is provided. To carry out such operation, a secondary battery module includes a plurality of secondary batteries, a DC/DC converter, a switch, and a control circuit.
1. A secondary battery module comprising:
a first lithium-ion secondary battery and a second lithium-ion secondary battery electrically connected to each other, each of the first lithium-ion secondary battery and the lithium-ion second secondary battery having a positive electrode and a negative electrode;
an input terminal configured to be electrically connected to a power source;
an output terminal;
a first DC/DC converter, wherein a first terminal of the first DC/DC converter is electrically connected to a first electrode of the first lithium-ion secondary battery, and a second terminal of the first DC/DC converter is electrically connected to a first electrode of the second lithium-ion secondary battery;
an AC/DC converter, wherein a first terminal of the AC/DC converter is electrically connected to the input terminal of the secondary battery module;
a DC/AC converter, wherein a first terminal of the DC/AC converter is electrically connected to the output terminal of the secondary battery module;
a first switch, wherein a first terminal of the first switch is electrically connected to the first terminal of the first DC/DC converter, and a second terminal of the first switch is electrically connected to a second terminal of the AC/DC converter;
a second switch, wherein a first terminal of the second switch is electrically connected to the second terminal of the first DC/DC converter, and a second terminal of the second switch is electrically connected to a second terminal of the DC/AC converter; and
a control circuit functionally connected to the first DC/DC converter, the AC/DC converter, the DC/AC converter, the first switch, and the second switch,
wherein the control circuit is configured to insert a discharging period of one of the first and second lithium-ion secondary batteries into a charging period of the secondary battery module, thereby dissolving deposits comprising lithium on the negative electrode of the one of the first and second lithium-ion secondary batteries by discharging with current density higher than that for charging, and
wherein the deposits are dissolved while constant current is supplied from the power source to secondary battery module.
2. The secondary battery module according to claim 1 ,
wherein each of the first lithium-ion secondary battery and the second lithium-ion secondary battery includes a plurality of secondary battery cells, and
wherein the plurality of secondary battery cells are electrically connected to each other in series.
3. The secondary battery module according to claim 2 , further comprising:
a protection circuit and a current detector electrically connected to the plurality of secondary battery cells.
4. The secondary battery module according to claim 1 , wherein the second terminal of the first switch is electrically connected to the second terminal of the second switch.
5. The secondary battery module according to claim 1 , wherein in the discharging period of the one of the first and second lithium-ion secondary batteries, the other of the first and second lithium-ion secondary batteries is charged with discharging current from the one of the first and second lithium-ion secondary batteries.
6. The secondary battery module according to claim 1 , wherein the second terminal of the AC/DC converter is directly connected to the second terminal of the DC/AC converter.
7. The secondary battery module according to claim 1 , wherein a length of the discharging period of the one of the first and second lithium-ion secondary batteries is 1/100 to ⅓ of a length of the charging period of the secondary battery module.
8. A secondary battery module comprising:
a first lithium-ion secondary battery and a second lithium-ion secondary battery electrically connected to each other, each of the first lithium-ion secondary battery and the lithium-ion second secondary battery having a positive electrode and a negative electrode;
an input terminal configured to be electrically connected to a power source;
an output terminal;
a first DC/DC converter, wherein a first terminal of the first DC/DC converter is electrically connected to a first electrode of the first lithium-ion secondary battery, and a second terminal of the first DC/DC converter is electrically connected to a first electrode of the second lithium-ion secondary battery;
a second DC/DC converter, wherein a first terminal of the second DC/DC converter is electrically connected to the first electrode of the first lithium-ion secondary battery, and a second terminal of the second DC/DC converter is electrically connected to the first electrode of the second lithium-ion secondary battery;
an AC/DC converter, wherein a first terminal of the AC/DC converter is electrically connected to the input terminal of the secondary battery module;
a DC/AC converter, wherein a first terminal of the DC/AC converter is electrically connected to the output terminal of the secondary battery module;
a first switch, wherein a first terminal of the first switch is electrically connected to the first terminal of the first DC/DC converter and the first terminal of the second DC/DC converter, and a second terminal of the first switch is electrically connected to a second terminal of the AC/DC converter;
a second switch, wherein a first terminal of the second switch is electrically connected to the second terminal of the first DC/DC converter and the second terminal of the second DC/DC converter, and a second terminal of the second switch is electrically connected to a second terminal of the DC/AC converter; and
a control circuit functionally connected to the first DC/DC converter, the second DC/DC converter, the AC/DC converter, the DC/AC converter, the first switch, and the second switch,
wherein the control circuit is configured to insert a discharging period of one of the first and second lithium-ion secondary batteries into a charging period of the secondary battery module, thereby dissolving deposits comprising lithium on the negative electrode of the one of the first and second lithium-ion secondary batteries by discharging with current density higher than that for charging, and
wherein the deposits are dissolved while constant current is supplied from the power source to secondary battery module.
9. The secondary battery module according to claim 8 ,
wherein each of the first lithium-ion secondary battery and the second lithium-ion secondary battery includes a plurality of secondary battery cells, and
wherein the plurality of secondary battery cells are electrically connected to each other in series.
10. The secondary battery module according to claim 9 , further comprising:
a protection circuit and a current detector electrically connected to the plurality of secondary battery cells.
11. The secondary battery module according to claim 8 , wherein the second terminal of the first switch is electrically connected to the second terminal of the second switch.
12. The secondary battery module according to claim 8 , wherein in the discharging period of the one of the first and second lithium-ion secondary batteries, the other of the first and second lithium-ion secondary batteries is charged with discharging current from the one of the first and second lithium-ion secondary batteries.
13. The secondary battery module according to claim 8 , wherein the second terminal of the AC/DC converter is directly connected to the second terminal of the DC/AC converter.
14. The secondary battery module according to claim 8 , wherein a length of the discharging period of the one of the first and second lithium-ion secondary batteries is 1/100 to ⅓ of a length of the charging period of the secondary battery module.
15. A secondary battery module comprising:
a first lithium-ion secondary battery and a second lithium-ion secondary battery electrically connected to each other, each of the first lithium-ion secondary battery and the lithium-ion second secondary battery having a positive electrode and a negative electrode;
a DC/DC converter, wherein a first terminal of the DC/DC converter is electrically connected to a first electrode of the first lithium-ion secondary battery, and a second terminal of the DC/DC converter is electrically connected to a first electrode of the second lithium-ion secondary battery;
an input terminal electrically connected to the first lithium-ion secondary battery, the second lithium-ion secondary battery, and the DC/DC converter, wherein the input terminal is configured to be electrically connected to a power source;
an output terminal electrically connected to the input terminal, the first lithium-ion secondary battery, the second lithium-ion secondary battery, and the DC/DC converter;
a first switch, wherein a first terminal of the first switch is electrically connected to the first terminal of the DC/DC converter, and a second terminal of the first switch is electrically connected to the input terminal and the output terminal;
a second switch, wherein a first terminal of the second switch is electrically connected to the second terminal of the DC/DC converter, and a second terminal of the second switch is electrically connected to the input terminal, the output terminal, and the second terminal of the first switch; and
a control circuit functionally connected to the DC/DC converter, the first switch, and the second switch,
wherein the control circuit is configured to alternately insert discharging periods of the first and second lithium-ion secondary batteries into a charging period of the secondary battery module, thereby dissolving deposits comprising lithium on the negative electrode of the one of the first and second lithium-ion secondary batteries by discharging with current density higher than that for charging, and
wherein the deposits are dissolved while constant current is supplied from the power source to secondary battery module.
16. The secondary battery module according to claim 15 ,
wherein each of the first lithium-ion secondary battery and the second lithium-ion secondary battery includes a plurality of secondary battery cells, and
wherein the plurality of secondary battery cells are electrically connected to each other in series.
17. The secondary battery module according to claim 16 , further comprising:
a protection circuit and a current detector electrically connected to the plurality of secondary battery cells.
18. The secondary battery module according to claim 15 , further comprising:
an AC/DC converter electrically connected to the second terminal of the first switch and the input terminal; and
a DC/AC converter electrically connected to the second terminal of the second switch and the output terminal.
19. The secondary battery module according to claim 18 , the AC/DC converter is directly connected to the DC/AC converter.
20. The secondary battery module according to claim 15 , wherein in one discharging period of one of the first and second lithium-ion secondary batteries, the other of the first and second lithium-ion secondary batteries is charged with discharging current from the one of the first and second lithium-ion secondary batteries.
21. The secondary battery module according to claim 15 , wherein a length of the discharging period of the one of the first and second lithium-ion secondary batteries is 1/100 to ⅓ of a length of the charging period of the secondary battery module.