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Material for lithium secondary battery of high performance

A lithium layer, mixed lithium technology, applied in secondary batteries, lithium storage batteries, battery electrodes, etc., can solve the problems of structural expansion, deterioration of cycle characteristics, deterioration, etc.

Inactive Publication Date: 2008-11-05
LG CHEM LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the cathode active material thus prepared, in the charged state, suffers from structural expansion and instability due to the repulsive force between oxygen atoms, and there is a problem that cycle characteristics are severely deteriorated due to repeated charge / discharge cycles.
[0008] Second, LiNiO 2 Problems with excess gas evolution during storage or cycling
In addition, LiNiO 2 The particles have an agglomerated secondary particle structure in which primary particles agglomerate to form secondary particles and thus further increase the contact area with the electrolyte, resulting in CO 2 Severe gas evolution which in turn unfortunately leads to cell swelling and deterioration of high temperature safety
[0009] Third, when exposed to air and moisture, LiNiO 2 The chemical resistance of the surface is significantly reduced and the slurry gels due to polymerization of the NMP-PVDF slurry due to high pH
LiNiO 2 These characteristics of the battery create serious handling problems in battery production
[0010] Fourth, high-quality LiNiO 2 cannot be achieved by a simple solid-state reaction (such as the preparation of LiCoO 2 prepared by the reaction used in ), the LiNiMeO containing the essential dopant cobalt and the dopant manganese and aluminum 2 (Me=Co, Mn or Al) cathode active material is obtained by a lithium source such as LiOH·H 2 O with a mixed transition metal hydroxide in an atmosphere of oxygen or syngas (i.e. CO deficient 2 prepared by reacting under the atmosphere), thus increasing the production cost
Although the foregoing oxide partially overlaps with the composition range of the present invention, it has been confirmed by various experiments conducted by the present inventors that it has a structure different from that of the lithium-mixed transition metal oxide of the present invention, that is, the existing The oxides of the technology have obvious problems related to severe gas evolution at high temperature and structural stability due to the large amount of impurities such as lithium carbonate, without a reversible lithium layer partially intercalating nickel ions

Method used

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  • Material for lithium secondary battery of high performance
  • Material for lithium secondary battery of high performance
  • Material for lithium secondary battery of high performance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0116] A formula MOOH (M=Ni 4 / 15 (Mn 1 / 2 Ni 1 / 2 ) 8 / 15 Co 0.2 ) mixed hydroxides as mixed transition metal precursors, with Li 2 CO 3 Mixing in a certain stoichiometric ratio (Li:M=1.02:1) and sintering the mixture in air at various temperatures between 850 and 1000°C for 10 hours to obtain a lithium-mixed transition metal oxide. Here, the secondary particles maintain an intact shape without collapse, and the crystal size becomes larger as the sintering temperature increases.

[0117] From the results of X-ray analysis, it was confirmed that all samples had a good layered crystal structure. In addition, the unit cell volume did not change significantly with increasing sintering temperature, thus indicating no apparent oxygen deficiency and no apparent increase in cation mixing, and essentially no lithium evaporation.

[0118] The crystallographic data of the thus prepared mixed lithium transition metal oxide is shown in Table 1 below, and its FESEM image is as follows ...

Embodiment 2

[0133] Samples of mixed lithium transition metal oxides were subjected to pH titration prior to exposure to moisture as in Example 2 and stored at 60°C in air in a wet chamber (90% RH) for separate storage 17 hours and 3 days. The result obtained in this way is Figure 9 shown. The mixed lithium transition metal oxide of Example 2 (see Figure 9 ) and the sample of Comparative Example 3 (see Figure 8 ) for comparison, the sample of Comparative Example 3 (storage for 17 hours) consumed about 20 mL of HCl, while the sample of Example 2 (storage for 17 hours) consumed 10 mL of HCl, thus indicating that the water-soluble base produced was reduced by about half. In addition, in the samples stored for 3 days, the sample of Comparative Example 3 consumed about 110 mL of HCl, while the sample of Example 2 consumed 26 mL of HCl, which corresponds to a reduction of water-soluble base produced by about one-fifth. Therefore, it can be seen that the decomposition rate of the sample of...

Embodiment 3

[0137] put a Li 2 CO 3 And formula MOOH (M=Ni 4 / 15 (Mn 1 / 2 Ni 1 / 2 ) 8 / 15 Co 0.2 ) The mixture of mixed hydroxides was introduced into a furnace of about 20L chamber and sintered at 920°C for 10 hours, during which time more than 10m 3 The air was pumped into the furnace, from which about 5 kg of LiNiMO was prepared in one batch 2 .

[0138] After the sintering is completed, the unit cell constant is determined by X-ray analysis, and the unit cell volume is compared with the target value (Sample B of Example 1: 33.921 )Compare. ICP analysis confirmed that the Li to M ratio was very close to 1.00, and the unit cell volume distribution was within the target range. Figure 10 SEM images of the cathode active material thus prepared are shown, and Figure 11 Rietveld actuarial results are shown. As shown in these figures, it can be confirmed that this sample has high crystallinity and a good layered structure, and the Ni intercalated in the reversible lithium layer 2+ T...

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Abstract

Provided is a lithium mixed transition metal oxide having a composition represented by Formula I of LixMyO2 (M, x and y are as defined in the specification), wherein lithium ions intercalate into and deintercalate from mixed transition metal oxide layers (''MO layers'') and some of MO layer-derived Ni ions are inserted into intercalation / deintercalation layers of lithium ions (''reversible lithium layers'') thereby resulting in the interconnection between the MO layers. The lithium mixed transition metal oxide of the present invention has a stable layered structure and therefore exhibits improved stability of the crystal structure upon charge / discharge. In addition, a battery comprising such a cathode active material can exhibit a high capacity and a high cycle stability. Further, such a lithium mixed transition metal oxide is substantially free of water-soluble bases, and thereby can provide excellent storage stability, decreased gas evolution and consequently superior high-temperature stability with the feasibility of low-cost mass production.

Description

technical field [0001] The present invention relates to a transition metal oxide of Ni-based mixed lithium and a secondary battery cathode active material comprising the Ni-based mixed lithium transition metal oxide. More specifically, the transition metal oxide of Ni-based mixed lithium of the present invention has a certain composition, and wherein lithium ions can be inserted / extracted from the mixed transition metal oxide layer ("MO layer"), and through some of the MO layer. The resulting Ni ions are intercalated into the intercalation / extraction layers of lithium ions (reversible lithium layers) to interconnect the MO layers, thereby improving the stability of the crystal structure during charge / discharge to provide excellent sintering stability. In addition, batteries containing such a cathode active material can have high capacity and high cycle stability. In addition, this lithium-mixed transition metal oxide has excellent storage stability and chemical resistance due...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/131H01M4/48H01M4/485H01M4/50H01M4/505H01M4/52H01M4/525H01M10/052H01M10/0525H01M10/36
CPCH01M4/505C01G53/50H01M4/525C01P2002/77H01M10/052C01P2006/40C01P2002/54H01M10/0525C01P2006/11H01M4/485Y02E60/122C01P2002/72H01M4/131C01P2006/80Y02E60/10Y02P20/129
Inventor 朴洪奎申先植朴信英申昊锡J·M·保罗森
Owner LG CHEM LTD
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