Battery system for secondary battery comprising blended cathode material, and apparatus and method for managing the same

• US 10,283,819 B2
• Filed: 12/08/2014
• Issued: 05/07/2019
• Est. Priority Date: 04/13/2012
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Joe, Won-Tae, Chung, Geun-Chang, Cha, Sun-Young
• Primary Examiner(s): Ishizuka, Yoshihisa
• Application Number:
  US14/563,169
• Publication Number:
  US 20150086812A1
• Time in Patent Office: 1,611 Days
• Field of Search: 702 63
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Disclosed is a battery system for a secondary battery including a blended cathode material, and an apparatus and method for managing a secondary battery having a blended cathode material. The blended cathode material includes at least a first cathode material and a second cathode material. The first and second cathode materials have different operating voltage ranges. When the secondary battery comes to an idle state or a no-load state, the battery system detects a voltage relaxation occurring by the transfer of operating ions between the first and second cathode materials.

Claims

1. A battery system, comprising:

(1) a battery management system (BMS); and

(2) a blended lithium secondary battery, comprising;

(a) a cathode comprising a first cathode material and a second cathode material different from the first cathode material, wherein the first and second cathode materials have different operating voltage ranges;

(b) an anode; and

(c) a separator,

wherein the BMS is electrically connected to the blended lithium secondary battery and includes a sensor configured to measure a current and a voltage of the blended lithium secondary battery, and

wherein the BMS is configured to;

control the charge and discharge of the blended lithium secondary battery in a voltage range where the blended lithium secondary battery undergoes voltage relaxation;

monitor the current and voltage of the blended lithium secondary battery during operation of the blended lithium secondary battery according to time using the sensor;

detect a two-stage voltage relaxation from the change of voltage of the blended lithium secondary battery during operation of the battery system, wherein the voltage relaxation includes the transfer of operating ions between the first and second cathode active materials;

estimate a state of charge of the blended lithium secondary battery corresponding to the detected two-state voltage relaxation; and

update the state of charge of the blended lithium secondary battery based on the estimated state of charge.

2. The battery system according to claim 1, wherein the BMS detects the two-stage voltage relaxation when the occurrence of an inflection point is identified in a changing pattern of the voltage, and

wherein the two-stage voltage relaxation includes two voltage rises before and after the inflection point.

3. The battery system according to claim 2, wherein the BMS identifies the occurrence of the inflection point by using a first-order differential value or a second-order differential value of the voltage of the blended lithium secondary battery with respect to time.

4. The battery system according to claim 2,

wherein the BMS determines a reference parameter including a voltage corresponding to the inflection point, a time corresponding to the inflection point, a first-order differential value with respect to time calculated at the inflection point, a value obtained by integrating the voltage profile between predetermined two points before and after the inflection point, a first-order differential value or second-order differential value of the voltage profile calculated at a predetermined point before and/or after the inflection point with respect to time, or combinations thereof, and

wherein a state of the blended lithium secondary battery corresponding to the determined reference parameter is estimated by using a predetermined relationship between the reference parameter and the state of the blended lithium secondary battery.

5. The battery system according to claim 4, wherein the predetermined relationship is a look-up table which is capable of mapping a state of the blended lithium secondary battery by means of at least one reference parameter.

6. The battery system according to claim 4, wherein the predetermined relationship is a look-up function where at least one reference parameter and a state of the blended lithium secondary battery corresponding thereto are respectively defined as an input parameter and an output parameter.

7. The battery system according to claim 1, wherein the BMS monitors the current and voltage of the blended lithium secondary battery when the blended lithium secondary battery comes to an idle state or a no-load state while being discharged.

8. The battery system according to claim 1, wherein the first cathode material has a layered structure and the second cathode material has an olivine structure, and

wherein the first cathode material and the second cathode material are blended in a weight ratio of 7:

3.

9. The battery system according to claim 8, wherein the first cathode material comprises Li_1+xNi_aCo_b, Mn_cO₂ (NMC), where x>

0;

a=b=c=⅓

, and

wherein the second cathode material comprises LiFePO₄ (LFP).