锂离子电池安全的设计与维护

040

The Design and Preservation of the Safety of Lithium-ion Battery

LiFePO4 LiCoO2

PTC

LiFePO4

Separator has much influence on the electrical properties and safety of the Cell. Microporous poly-

meric membranes must be mechanically strong enough to keep the structure integrity while shutdown activated. Inorganic composite membranes show a higher ability than Microporous polymeric mem-

branes to withstand overcharge. Two types of overcharge protector are introduced and each of these

has a specific redox potential range that suitable for LiFePO4 and LiCoO2 respectively. Phosphor contented fire-retardant additive prevents the cell from overheating. A carbon and polymer composite

with PTC properties is introduced into the cathode preparation. When the cell is heated over the

melting point of the polymer, the resistance of the cathode electrode increases drastically and cut-off

the current through it. That prevents the cell from thermal runaway. LiFePO4 has the character of overcharge protector too.

/Key Words

(Thermal Runaway) (Separator) (Overcharge Protector)

(Fire-retardant Additive) (PTC Cathode)

J. J. Lee1 C. R. Yang2

(MCL/ITRI) 1 2

60 70

1989 Li/MoS2

(1)

1990~1991 Nagoura

SONY Moli

041

1993 Bellcore 1991

PTC (Positive Temperature Coefficient) CID (Current Interrupt Device) (Safety Vent) (Thermal Fuse) (Thermostat)

(2)

(Thermal Runaway)

*

PC/EC/DMC(1/1/3) + LiPF 6 (1M)

DSC

042

(Tortuosity)

(MD) (TD) (Tensile

Strength) (Puncture Strength)

(Nonwoven Fiber Mats)

(Microporous Polymeric Membranes)

(Inorganic Composite Membranes)

1.

60~80% 20~50

µm 100~200 µm

(3)

(4)

2.

PE PP PE/PP

HDPE

20 µm

40% 1000 kg/cm2

300

90°C 1

5%

(Shutdown)

PE

PP/PE/PP

043

HDPE 135°C PE PP PP/PE PE 120~130°C PP

3.

Sol-Gel (EC, PC, γ-GBL)

(5)

Ceramic Coating

Support

5 µm

100 µm

044 SEI

1.

(Anisole)

3.8~

4.0 V vs. Li+/Li (6)

LiFePO4 −3,5−

(Trimethyl-3,5-xylylsilane)

4.7 V LiCoO2

(7)

(Biphenyl)

(Aryladamantanes)

4.6 V LiCoO2

(8) LiBOB

(9)

LiPF6

LiBOB

2.

Trimethyl Phosphate 1M LiPF6

1.2 V TMP

TMP

EC 12%

DME 70% (10)

Tris(2,2,2-trifluoroethyl) Phosphate

0.3V

(11) Cyclophosphazene

(12)

P(III) Tris(2,2,2-trifluoroethyl)

Phosphite

(13)

PTC

PTC

HDPE