Method of Estimating Surface Ion Density

• US 20100072955A1
• Filed: 09/23/2008
• Published: 03/25/2010
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: ISHIKAWA, Yosuke
• Granted Patent: US 7,919,966 B2
• Time in Patent Office: Days
• US Class Current: 320/160
• 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 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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: Y02E 60/10 Energy storage using batteries

Abstract

The present teachings are directed toward machine implemented method for estimating the ion density of the surface of either positive or negative electrode of a battery. The machine-implemented method includes dividing each electrode into N layers of active electrode material, determining the ion density variable for each one of the N layers of the active electrode, and determining the ion density of the electrode surface. In the presently disclosed method, the ion density variable of each of the N layers of the active electrode changes as a function of the difference between the respective ion density variables of adjacent N layers, and the ion density of the electrode surface changes as a function of the battery current and the difference between the respective ion density variables of adjacent N layers. The present method is particularly applicable to Li-ion batteries.

Claims

1. A machine implemented method for estimating the ion density of the surface of either positive or negative electrode of a battery, the machine-implemented method comprising:

dividing each electrode into N layers of active electrode material;

determining a battery current applied to the electrode of the battery;

determining the ion density variable for each one of the N layers of the active electrode material; and

determining the ion density of the electrode surface, and

wherein the ion density variable of each of the N layers of the active electrode material comprises a function of the difference between the respective ion density variables of adjacent N layers, and

wherein the ion density of the electrode surface comprises a function of the battery current and the difference between the respective ion density variables of adjacent N layers.

2. The machine implemented method according to claim 1, wherein the ion density of the electrode surface comprises the ion density variable of the 0^th layer of active electrode material.

3. The machine implemented method according to claim 1, wherein the ion density of the 0^th layer of active electrode material comprises the solution to the following equation:

4. The machine implemented method according to claim 1, wherein the ion density variable for each of the 1^st through the N−

2^th layer of active electrode material comprises the respective solutions to the following equation;

C_ij(k+1)=C_ij(k)+D_{diff j}(C<sub>i−

1j</sub>(k)−

C_1j(k))−

D_{diff j}(C_ij(k)−

C_i+1j(k)

for i equal to 1 to N−

2.

5. The machine implemented method according to claim 1, wherein the ion density variable of the N−

1^th layer of active electrode material comprises the solution to the following equation;

C<sub>N−

1j</sub>(k+1)=C<sub>N−

1j</sub>(k)+D_{diff j}(C<sub>N−

2j</sub>(k)−

C<sub>N−

1j</sub>(k)).

6. The machine implemented method according to claim 1, wherein the battery comprises a lithium ion battery.

7. A battery charging device for a battery comprising:

a battery;

a battery charger for charging the battery; and

a charging control means comprising a machine implemented method for estimating the ion density of the surface of either positive or negative electrode of the battery, the machine-implemented method comprising;

dividing each electrode into N layers of active electrode material;

determining a battery current applied to the electrode of the battery;

determining the ion density variable for each one of the N layers of the active electrode material; and

determining the ion density of the electrode surface, and

wherein the ion density variable of each of the N layers of the active electrode material comprises a function of the difference between the respective ion density variables of adjacent N layers, and

wherein the ion density of the electrode surface comprises a function of the battery current and the difference between the respective ion density variables of adjacent N layers.

8. A battery charging device for a battery according to claim 7, wherein the battery charger for charging the battery comprises a generator.

9. A battery charging device for a battery according to claim 7, wherein the battery charger for charging the battery comprises a generator for a hybrid electric vehicle.