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Polymer-coated active material and lithium secondary battery using the same

An active material and secondary battery technology, applied in secondary batteries, battery electrodes, circuits, etc., can solve problems such as battery life degradation, uneven heating of batteries, and deviation of lithium ion storage and release, so as to improve load characteristics, long life effect

Inactive Publication Date: 2013-03-27
HITACHI LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] When the charging or discharging current value of the lithium-ion battery is increased, the current per unit area of ​​the electrode (i.e., the current density) increases, so uneven heating occurs inside the battery, sometimes depending on the position of the electrode surface. Deviations in the amount of storage and release of lithium ions caused by
In that case, there is a problem that the life of the battery that is subjected to a large stress due to charging and discharging is deteriorated

Method used

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  • Polymer-coated active material and lithium secondary battery using the same
  • Polymer-coated active material and lithium secondary battery using the same
  • Polymer-coated active material and lithium secondary battery using the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0157] 〈Making of positive electrode〉

[0158] Utilize the positive electrode active material LiNi with an average particle size of 10 μm 1 / 3 mn 1 / 3 co 1 / 3 o 2, The following test was carried out on a positive electrode made of carbon black as a conductive agent and polyvinylidene fluoride (PVDF) as a binder. The weight composition of the positive electrode active material, the conductive agent, and the binder is set to 88:7:5. The area of ​​the electrode coated with the positive electrode slurry was set at 400 cm×5 cm, and the thickness of the mixture was set at 50 μm. In addition, the polymer compound of the present invention was not used for the positive electrode.

[0159] 〈Making of Negative Electrode〉

[0160] As the negative electrode active material, natural graphite with an average particle size of 15 μm is used, and as the polymer compound, [CH 3 -(OCH 2 CH 2 )nCO] 2 O (in structure I, X is CH 3 -, Y is a single bond, R is H, and n is 200 to 300) of carbox...

Embodiment 2

[0169] 〈Making of Negative Electrode〉

[0170] In Example 1, the n of the polymer compound was increased to 600 to 700, and the negative electrode was manufactured with the other conditions being the same as in Example 1.

[0171]

[0172] The initial capacity after initial aging was 1.8±0.1 Ah. The reason why the initial capacity is lower than in Example 1 is that the initial DC resistance is also increased by 20 to 30%. The capacity retention after 500 cycles at 50°C was 93±2%. The capacity retention rate was almost the same as the result of Example 1, but the initial capacity was low, so the capacity after 500 cycles also decreased.

Embodiment 3

[0174] 〈Making of Negative Electrode〉

[0175] In Example 1, the binder (styrene-butadiene rubber) used in the negative electrode was omitted, and a negative electrode with an increased amount of negative active material was produced instead. That is, the weight composition of natural graphite, polymer compound, binder, and tackifier was set to 96.5:2:0:1.5.

[0176] Other conditions were the same as in Example 1, and were produced and evaluated.

[0177]

[0178] The capacity retention rate (the ratio of the discharge capacity to the initial capacity of 2 ± 0.1 Ah) after 500 cycles was 91 ± 2%. The DC resistance increased by 160±10% from the initial value.

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Abstract

Provided is a lithium ion secondary battery including a cathode that is capable of occluding and emitting lithium ions, and an anode that is capable of occluding and emitting the lithium ions. A polymer compound containing a polyether portion and a carboxylic acid bonding portion is bonded to an active material as shown with a structure I, a structure II, a structure III, and a structure IV.

Description

technical field [0001] The present invention relates to a coated active material and a lithium secondary battery using the coated active material. Background technique [0002] Lithium-ion batteries typified by lithium-ion batteries have high energy density and are attracting attention as batteries for electric vehicles and power storage. In particular, electric vehicles include zero-emission electric vehicles without an engine, hybrid electric vehicles equipped with both an engine and a secondary battery, and plug-in hybrid electric vehicles charged directly from a system power supply. In addition, application as a stationary power storage system that stores power and supplies power in an emergency after a power system is disconnected is also expected. [0003] Lithium-ion batteries are required to have a large output and excellent durability for such various applications. That is, power supplies for mobile vehicles require output performance at a rate of 0.1 hour or more...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/62H01M10/0525
CPCH01M4/366H01M4/60H01M4/88H01M10/0525Y02E60/12Y02E60/50Y02T10/7011Y02E60/122Y02E60/10Y02P70/50
Inventor 西村悦子西村胜宪田中明秀森岛慎
Owner HITACHI LTD
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