JP2000173586A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte secondary battery having a high capacity and excellent in cyclic characteristics. SOLUTION: Each composite particle is structured so that part or the whole of the peripheral surface of nuclear particle consisting of solid phase A is covered with another solid phase B, wherein the solid phase A contains at least tin while the phase B is a solid solution or intermetallic compound of tin as the phase A constituent element and at least one of the group II elements, transition elements, group XII and XIII elements, and group XIV elements except carbon in the periodic table excluding the above-mentioned constituent element of the phase A, and these composite particles are used as a negative electrode material, and thereto either of the oxide, sulfide, selenide and telluride of the above-mentioned metals or admixture thereof is added as a substance to make irreversible reductive reaction with lithium ions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an improvement in a negative electrode material of a non-aqueous electrolyte secondary battery, and an improvement in electrochemical characteristics such as charge / discharge capacity and charge / discharge cycle life by adding a special additive to the negative electrode. The present invention relates to a non-aqueous electrolyte secondary battery used for a portable information terminal, a portable electronic device, a small household power storage device, a motorcycle powered by a motor, an electric vehicle, a hybrid electric vehicle, and the like.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries used as main power sources for mobile communication devices and portable electronic devices have the characteristics of high electromotive force and high energy density.
A lithium secondary battery using lithium metal as the negative electrode material has a high energy density, but dendrites are deposited on the negative electrode during charging, and may repeatedly break through the separator to reach the positive electrode side by repeated charging and discharging, causing an internal short circuit. there were. Further, the precipitated dendrite has a high specific activity because of its large specific surface area, and reacts with the solvent in the electrolytic solution on its surface to form a solid electrolyte interface film lacking electron conductivity. For this reason, the internal resistance of the battery is increased, and particles isolated from the electron conduction network are present, and these are factors that lower the charge / discharge efficiency. For these reasons, lithium secondary batteries using lithium metal as the negative electrode material have problems with low reliability and short cycle life.

At present, a carbon material capable of occluding and releasing lithium ions is used as a negative electrode material instead of lithium metal, and has been put to practical use. Normally, metallic lithium does not precipitate on the carbon material negative electrode, so there is no problem of internal short circuit due to dendrite. However, the theoretical capacity of graphite, one of the carbon materials, is 372 mAh / g, which is 10% of the theoretical capacity of Li metal alone.
It is as small as one-third.

As another negative electrode material, tin (Sn) is known as a simple metal material forming a compound with lithium. Composition formula of the most compound including lithium tin (Sn) is a Li ₂₂ Sn _5, respectively, the metal lithium is in this range because it does not usually deposited, there is no problem of internal short circuit due to dendrite. The electrochemical capacity between these compounds and each single material is 993 mAh / g, each of which is larger than the theoretical capacity of graphite.

In addition to a simple metal material and a simple non-metal material which form a compound with lithium, as a compound negative electrode material, a non-ferrous metal silicide comprising a transition element is disclosed in JP-A-7-240201. No. 63651 discloses an intermetallic compound containing a Group 4B element and at least one of P and Sb, and has a crystal structure of CaF ₂ type, ZnS type, or AlL.
Negative electrode materials made of any of the iSi type have been proposed.

On the other hand, as a positive electrode active material, a lithium transition metal composite oxide exhibiting a high charge / discharge voltage, for example, LiCoO 2
₂ (for example, JP-A-55-136131) and LiNiO ₂ (for example, US Pat.
No. 302518), a composite oxide of a plurality of metal elements and lithium (for example, Li _y Ni _x Co _1-x O ₂ : Japanese Patent Application Laid-Open No. Sho 63)
-299056 _{discloses, Li x M y N z O} 2 ( where, M is F
e, at least one selected from Co, Ni, and N
Is a non-aqueous electrolyte secondary battery using at least one selected from Ti, V, Cr, and Mn): Japanese Patent Application Laid-Open No. Hei 4-267053) as a positive electrode active material and utilizing insertion and extraction of lithium ions. Have been.

In particular, LiNiO ₂ has been actively researched and developed because the supply amount of Ni as a raw material is stable, and it is expected to be inexpensive and have a high capacity.

[0008]

However, the negative electrode materials having higher capacities than the above-mentioned carbon materials have the following problems, respectively.

A single metal material and a single nonmetallic negative electrode material which form a compound with lithium commonly have poor charge / discharge cycle characteristics as compared with a carbon negative electrode material. The reason is not clear, but I think as follows.

[0010] Tin contains four tin atoms in the crystallographic unit cell (tetragonal, space group I4 ₁ / amd). Lattice constant a
= 0.5820nm, c = 0.3175nm, the unit cell volume is
0.1075 nm ³ and the volume occupied by one tin atom is 26.9 × 1
0 is ^-3 nm ^3. Judging from the phase diagram of the tin-lithium binary system, the formation of an electrochemical compound with lithium at room temperature indicates that the two phases of tin and the compound Li ₂ Sn ₅ coexist at the beginning of the reaction. Conceivable. The crystallographic unit cell of Li ₂ Sn ₅ (tetragonal, space group P4 / mbm) contains 10 tin atoms. Its lattice constant a = 1.0274nm, c = 0.3125nm
Calculated from, the unit cell volume is 0.32986 nm ³ , and the volume per tin atom (the value obtained by dividing the unit cell volume by the number of tin atoms in the unit cell) is 33.0 × 10 ⁻³ nm ³ . According to this value, when tin becomes the compound Li ₂ Sn ₅ ,
The volume of the material will expand 1.23 times. Further, when the electrochemical compound formation reaction with lithium proceeds, a lithium-rich compound Li ₂₂ Sn ₅ is finally produced. L
The crystallographic unit cell (cubic, space group F23) of i ₂₂ Sn ₅ contains 80 tin atoms. Its lattice constant a = 1.
In terms of 978 nm, unit cell volume is 7.739nm ^3,
The volume per tin atom (the value obtained by dividing the unit cell volume by the number of tin atoms in the unit cell) is 96.7 × 10 ⁻³ nm ³ . This value is 3.59 times that of simple tin, and the material expands significantly.

As described above, tin undergoes a large change in the volume of the negative electrode material due to the charge / discharge reaction, and a repetition of a change in a state in which two phases having a large volume difference coexist causes cracks in the material and fine particles. It is considered something. It is considered that in the miniaturized material, a space is generated between particles, the electron conduction network is divided, a portion that cannot participate in an electrochemical reaction increases, and the charge / discharge capacity decreases.

That is, a large volume change of a simple metal material forming a compound with lithium, and a structural change due to the large volume change,
It is speculated that this is the reason why the charge / discharge cycle characteristics are worse than the carbon anode material.

On the other hand, unlike the above-mentioned simple material, it is composed of a non-ferrous metal silicide composed of a transition element or an intermetallic compound containing at least one of the group 4B element and P or Sb, and has a crystal structure of CaF ₂ type, ZnS A negative electrode material of any one of the negative electrode type and the AlLiSi type has been proposed as a negative electrode material having improved cycle life characteristics in JP-A-7-240201 and JP-A-9-63651, respectively.

Batteries using a non-ferrous metal silicide negative electrode material comprising a transition element disclosed in Japanese Patent Application Laid-Open No. 7-240201 were used in the first cycle, the 50th cycle, and the 100th cycle shown in Examples and Comparative Examples. From the battery capacity, the charge-discharge cycle characteristics are improved as compared with the lithium metal anode material, but the battery capacity is increased by only about 12% at the maximum as compared with the natural graphite anode material. Therefore, although not explicitly stated in the specification, it is considered that the non-ferrous metal silicide negative electrode material composed of a transition element has not been significantly increased in capacity as compared with the graphite negative electrode material.

Further, the materials disclosed in Japanese Patent Application Laid-Open No. 9-63651 have improved charge-discharge cycle characteristics as compared with the Li-Pb alloy negative electrode material in Examples and Comparative Examples, and have a higher performance than the graphite negative electrode material. It has been shown to be of high capacity. However, the discharge capacity is remarkably reduced in the charge / discharge cycles of 10 to 20 cycles, and even for Mg ₂ Sn which is considered to be the best, the capacity is reduced to about 70% of the initial capacity after about 20 cycles.

The positive electrode active materials reported so far (particularly, LiNi _x M _{1 -x} O ₂ (M is Co, Mn, Cr, F
e, V, and at least one selected from the group consisting of Al, where x: 1 ≧ x ≧ 0.5), in a potential region (4.3 V to 2 V vs. Li) normally used as a battery.
It is known that there is a large charge / discharge capacity difference between the second charge (lithium desorption reaction) and discharge (lithium insertion reaction). (Eg A. Rougier et al. Solid State I
onics 90, 83 (1996)). Fig. 1 schematically shows the potential behavior of the positive electrode and the negative electrode during initial charge and initial discharge of a battery using such a composite particle material having the same theoretical capacity as the positive electrode material. .

In FIG. 1, (AB) is the initial charge amount of the positive electrode, (BC) is the initial discharge capacity of the positive electrode and (C−C).
A) is the irreversible capacity of the positive electrode.

(A'-B ') is the initial charge amount of the negative electrode, which is the same as (AB) of the positive electrode. (B'-C ') is the initial dischargeable capacity of the negative electrode, and (C'-A') is the irreversible capacity of the negative electrode. Initial dischargeable capacity of negative electrode (B'-C ')
Since the capacity is larger than the initial discharge capacity (BC) of the positive electrode by (C′−D), the initial discharge capacity of the battery is regulated by the initial discharge capacity (BC) of the positive electrode. In the charge / discharge cycle after the first discharge, the positive electrode is between (BC) and the negative electrode is (B-C).
−C), the reaction reversibly changes between (B′−D) of the same volume. Therefore, lithium having a capacity equivalent to (C'-D) of the negative electrode remains in the negative electrode as "dead lithium" which cannot contribute to the charge / discharge reaction of the battery, and contributes to the improvement of the capacity of the battery without participating in the charge / discharge reaction. It is impossible.

Therefore, when the theoretical capacity of the positive and negative electrodes is adjusted by increasing the filling amount of the positive electrode so that the initial discharge capacity of the positive and negative electrodes after the initial charge becomes the same, (C−
"Death lithium" of the negative electrode of the difference between A) and (C'-A ')
A considerable amount of (C'-D) will overcharge the negative electrode.

However, there is a limit to the reversible charge capacity of the negative electrode active material, and if the charge exceeds the limit amount, it is deposited on the surface of the negative electrode plate as metallic lithium, and the deposited lithium reacts with the electrolyte. It deactivates, lowers the charge / discharge efficiency, and lowers the cycle life characteristics.

Therefore, it must be said that such a setting of the capacity of the positive and negative electrodes is inappropriate. In order to increase the capacity of a lithium ion secondary battery, it is necessary to select a positive and negative electrode material having a high initial charge / discharge efficiency and a large reversible capacity portion due to charge / discharge. In addition, the irreversible capacity portion of the positive electrode and the negative electrode and “dead lithium” must be reduced as much as possible, and care must be taken so that the negative electrode is not unnecessarily overcharged and metallic lithium is deposited.

However, when the initial charge / discharge efficiency of the negative electrode is larger than that of the negative electrode, it is difficult to design and configure the battery under the above-described conditions.

The present invention develops a high-capacity negative electrode active material, adjusts the theoretical capacity of the positive and negative electrodes for battery design, and examines various suitable negative electrode additives. Technology has been achieved.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a composite particle in which the whole or a part of the periphery of a core particle composed of a solid phase A is coated with a solid phase B, wherein the solid phase A contains at least tin as a constituent element, The solid phase B comprises tin which is a constituent element of the solid phase A;
Except for the above constituent elements, Group 2 elements of the periodic table, transition elements,
By using a material that is a solid solution or an intermetallic compound with at least one element selected from the group consisting of a Group 12 element, a Group 13 element, and a Group 14 element excluding carbon, the solid phase A has a higher capacity and a solid phase. B plays a role of suppressing expansion and contraction caused by charging and discharging of the solid phase A, thereby providing a negative electrode material having excellent charge / discharge cycle characteristics. Further, the negative electrode is electrochemically reduced to metal by charging. Non-aqueous electrolyte secondary battery composed of a mixture to which the metal compound is added, leaving no `` dead lithium '' that cannot participate in the charge / discharge reaction, and the negative electrode is not overcharged Thus, the battery was successfully designed and configured. With such a configuration, it is possible to provide a high-capacity nonaqueous electrolyte secondary battery having excellent cycle life. Since the solid phase A in the negative electrode material of the present invention contains at least tin having a high capacity as a constituent element, it is considered that the solid phase A mainly contributes to an increase in the charge / discharge capacity. Solid phase A
The solid phase B covering the whole or part of the periphery of the core particle composed of contributes to the improvement of the charge / discharge cycle characteristics, and the amount of lithium contained in the solid phase B is usually a metal, a solid solution,
Intermetallic compounds, each less than when alone.

Further, a metal compound which is electrochemically reduced to a metal by a reduction reaction is added to the new negative electrode active material.

As a compound to be added, a compound which reacts with lithium ions by a reduction reaction in a potential region between the positive electrode and the negative electrode is added.

The compound to be added is Ag as a metal oxide.
_TwoO, PbO, NiO, Ni_TwoO_Three, CoO, Co_TwoO_Three,
Co_ThreeO_Four, CuO, Cu_TwoO, Bi_TwoO_Three, Sb_TwoO_Three, C
r_TwoO _Three, MnO_Two, FeO_FourA few selected from the group consisting of
At least one kind is added.

The compound to be added is Ag as a metal sulfide.
₂ S, PbS, NiS, Ni ₂ S, Ni ₃ S ₄ , CoS, C
o ₂ S ₃ , Co ₃ S ₄ , CuS, Cu ₂ S, Bi ₂ S ₃ , Sb ₂
S ₃ , Sb ₂ S ₄ , Sb ₂ S ₅ , CrS, Cr ₂ S ₃ , Mn
S, Mn ₃ S ₄ , MnS ₂ , FeS, Fe ₂ S ₃ , FeS ₂ ,
At least one selected from the group consisting of Mo ₂ S ₃ and MoS ₂ is added.

As the metal selenide, Ag ₂ Se, P
bSe, Co ₂ Se ₃ , Co ₃ Se ₄ , CuSe, Cu ₂ S
e, Bi ₂ Se ₃ , Sb ₂ Se ₃ , Sb ₂ Se ₅ , Cr ₂ Se ₃
At least one selected from the group consisting of:

As the metal telluride, Ag ₂ Te, P
_{bTe, NiTe, Ni 2 Te 3} , CuTe, Cu 2 T
e, it is to add at least one selected from the group consisting of _{Bi 2 Te 3, Sb 2 Te} 3.

Of course, a mixture of these oxides, sulfides, selenides and tellurides may be used.

FIG. 2 is a schematic diagram showing the potential behavior of both the positive and negative electrodes during initial charging and initial discharging of the nonaqueous electrolyte secondary battery according to the present invention.

In FIG. 2, (AB) is the initial charge amount of the positive electrode, (BC) is the initial discharge capacity of the positive electrode and (CA).
Is the irreversible capacity of the positive electrode.

(A'-B ') is the initial charge amount of the negative electrode, which is the same as the charge amount (AB) of the positive electrode. The first charge of the negative electrode
First, after the metal compound added to the negative electrode is electrochemically reduced and the (A'-C ') component is charged, the negative electrode active material of the main material is charged with lithium ions. The initial charge amount of the negative electrode active material corresponds to (B'-C '). The initial discharge capacity (B'-D) of the negative electrode, which is the same as the capacity (BC) of the positive electrode.

The initial discharge capacities of these positive and negative electrodes are the respective reversible capacities. (C'-D)
Is the irreversible capacity of the negative electrode active material itself.

As can be fully understood from FIG. 2, in the present invention, the amount of the metal compound added to the negative electrode active material is determined from the irreversible capacity (CA) of the positive electrode to the irreversible capacity of the carbon material which is the main material of the negative electrode. Value (A'-
C ') applies.

The metal compound which is added to the negative electrode and electrochemically reduced by charging to irreversibly generate a metal has a large electrochemical equivalent weight, so that the amount of addition is small and the bulk specific gravity is low. Since it is high, the increase in volume is negligible even when added to the negative electrode.

As described above, the reversible capacity of the positive electrode and the negative electrode is maximized by adding the metal compound which is electrochemically reduced by charging, particularly the first charging, and which generates an irreversible metal to the negative electrode. At the same time, the negative electrode is substantially prevented from being unnecessarily overcharged in the charging and discharging after the second cycle, so that the cycle life is not deteriorated.

The amount of the compound added may be such that the irreversible capacity of the positive electrode is consumed, and is usually in the range of 0.2% to 20% with respect to the total amount of the main material which is the negative electrode active material. Is desirable.

The present invention is more effective when a lithium-containing metal oxide based on a lithium-containing nickel oxide having an initial charge / discharge efficiency of only 75 to 95% is used as a positive electrode material. is there.

If the positive electrode active material is a lithium-containing metal compound, LiCoO ₂ , LiNiO ₂ , LiMn ₂
Any compound that releases lithium ions such as O ₄ and contains occluded lithium may be used. However, when the charge / discharge efficiency of the first cycle (absorbed amount / emitted amount × 100 (%)) is in the range of 75 to 95%, Particularly large effects can be obtained.

Among them, the general formula Li as a positive electrode active material
_{x Ni 1-y M y O} z, (M = Na, Mg, Sc, Y, Mn,
Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, S
b, at least one of B), (where x = 0 to 1.
In particular, when the lithium-containing metal compound is represented by the formula 2, y = 0 to 0.9 and z = 2.0 to 2.3), the charge / discharge efficiency in the first cycle (occlusion / release amount × 100 (%)) Is preferred because of the small size.

When the positive electrode active material is synthesized at a high temperature,
Cycle charge / discharge efficiency (absorbed amount / released amount x 100
(%)) Is extremely small at 75% or less, and the discharge characteristics as an active material are deteriorated. Therefore, it is most effective when synthesized in a temperature range of 750 ° C. to 900 ° C.

As such an additive to the negative electrode, a compound mainly known as a positive electrode active material for a lithium primary battery using metallic lithium as a negative electrode is preferable.

If these compounds are, for example, NiS, metallic nickel is generated by a reduction reaction as shown in (Chemical Formula 1).

[0046]

Embedded image

Ni produced by the reaction of Chemical Formula 1 is chemically and electrochemically stable in a potential region where the negative electrode active material is charged and discharged, and is not oxidized and irreversible when the negative electrode is discharged. Maintains a metallic state by the nature. As described above, since the metal compound generates a metal at the time of the first charge, the conductivity in the negative electrode plate is remarkably improved, so that the internal resistance and polarization of the negative electrode can be reduced, and high capacity can be realized.

Further, since the reduction product does not form a compound with lithium, the reaction of formula (1) is an irreversible reaction, and no lithium release reaction occurs.

In the present invention, the metal oxide (Ag)_TwoO, P
bO, NiO, Ni_TwoO_Three, CoO, Co_TwoO_Three, Co
_ThreeO_Four, CuO, Cu_TwoO, Bi_TwoO_Three, Sb_TwoO_Three, Cr_TwoO
_Three, MnO_Two, Fe_ThreeO_Four), Metal sulfide (Ag_TwoS, Pb
S, NiS, Ni_TwoS, Ni_ThreeS_Four, CoS, Co_TwoS_Three,
Co_ThreeS_Four, CuS, Cu_TwoS, Bi_TwoS_Three, Sb_TwoS_Three, S
b_TwoS_Four, Sb_TwoS_Five, CrS, Cr_TwoS_Three, MnS, Mn_Three
S_Four, MnS_Two, FeS, Fe _TwoS_Three, FeS_Two, Mo
_TwoS_Three, MoS_Two), Metal selenide (Ag)_TwoSe, PbS
e, Co_TwoSe_Three, Co_ThreeSe_Four, CuSe, Cu_TwoSe,
Bi_TwoSe_Three, Sb_TwoSe_Three, Sb_TwoSe_Five, Cr_TwoSe_Three),
Metal telluride (Ag_TwoTe, PbTe, NiTe, N
i_TwoTe_Three, CuTe, Cu_TwoTe, Bi_TwoTe_Three, Sb_TwoT
e_ThreeIn both cases, the irreversible reaction proceeds and
It was confirmed that the same effect was obtained.

There has been reported an example in which a compound capable of absorbing or containing lithium ions is added as an additive to a carbonaceous material as a negative electrode (for example, FeO,
FeO ₂ , Fe ₂ O ₃ , SnO, SnO ₂ , MoO ₂ , V ₂ O
_{5, Bi 2 Sn 3 O 9} , WO 2, WO 3, Nb 2 O 5: JP 7
-192723, lithium-containing metal oxides, sulfides, hydroxides, selenides, and in the examples, lithium-containing (or bonded) Cu, Fe, Mo, Ti,
After mixing with a lithium salt with an oxide such as V, Nb, Mn, Co, or Ni, a compound obtained by heat treatment is used to obtain LiCuO ₃ ,
LiFeO ₂ , LiMoO ₃ , LiTiO ₂ , LiVO ₂ ,
LiNbO ₂ , Li ₂ MnO ₄ , LiCoO ₂ , LiNiO
₂ : JP-A-8-213053, Lithium occlusion /
A transition metal oxide capable of releasing _{Li p Ni q V 1-q} O r, p = 0.4~3, q
= 0 to 1, r = 1.2 to 5.5: JP-A-6-44972), and any of these reports in which a compound capable of occluding or containing lithium ions is added to the negative electrode, the negative electrode at the end of discharge or overdischarge It is added to prevent dissolution of the copper core material due to an increase in the potential and to improve the stability of the negative electrode, all of which are required to be reversible.

The purpose and effect of the present invention are completely different from those of a metal oxide which is electrochemically and irreversibly reduced to metal by initial charging as in the present invention. Also,
Since the state after the initial charge after the compound capable of inserting or storing lithium ions is a lithium-containing compound, the effect of improving conductivity as in the present invention cannot be obtained.

When the additive according to the present invention is used, it is irreversible when it reacts with lithium, so that an irreversible capacity larger than the negative electrode is charged and consumed by the negative electrode additive, so that the reversible charge / discharge capacity of the positive and negative electrodes can be reduced. Since the capacity of the configured secondary battery can be designed, a battery having higher energy density and good cycle characteristics can be realized.

Further, the compound (eg, Ni in the case of NiS) generated by reacting with the irreversible capacity lithium ion of the positive electrode during the initial charge improves the conductivity of the negative electrode plate and improves the discharge characteristics.

The positive electrode and the negative electrode used in the present invention are each composed of a positive electrode active material capable of electrochemically and reversibly inserting and releasing lithium ions and a mixture layer containing a conductive agent and a binder in a negative electrode material. It was constructed and constructed above.

The negative electrode material used in the present invention is a composite particle in which the whole or a part of the periphery of the core particle composed of the solid phase A is coated with the solid phase B, and the solid phase A contains at least tin as a constituent element. The solid phase B is composed of tin, which is a constituent element of the solid phase A, and a group 14 element excluding the constituent elements, a group 2 element, a transition element, a group 12, a group 13 element, and a carbon group other than carbon. A material that is a solid solution with at least one element selected from the group or an intermetallic compound (hereinafter, referred to as “composite particles”).

As one of the methods for producing the composite particles used in the present invention, a melt of the charged composition of each element constituting the composite particles is prepared by a dry spray method, a wet spray method, a roll quenching method, and a rotating electrode method. Rapid cooling and solidification by such as
There is a method of performing heat treatment at a temperature lower than the solidus temperature of the solid solution or the intermetallic compound determined by the charged composition.
(Necessary change) By rapid solidification of the melt, solid phase A particles as core particles and solid phase B covering the entire surface or a part of the periphery of the solid phase A particles are precipitated, and then heat treatment is performed.
The purpose of the present invention is to increase the uniformity of each of the solid phases A and B, but the composite particles according to claim 1 can be obtained even without heat treatment. In addition, any method other than the above-mentioned cooling method can be used as long as it can sufficiently cool.

As another manufacturing method, an adhesion layer made of an element other than the elements contained in the solid phase A necessary for forming the solid phase B is formed on the surface of the powder of the solid phase A.
There is a method of performing heat treatment at a temperature lower than the solidus temperature of the solid solution or the intermetallic compound determined by the charged composition. By this heat treatment, the component elements in the solid phase A diffuse into the adhesion layer, and the solid phase B is formed as a coating layer. The adhesion layer can be formed by a plating method or a mechanical alloying method. In addition, any method capable of forming an adhesion layer can be used.

The additive to be added to the negative electrode material in the present invention is preferably a compound which irreversibly reacts with lithium ions by a reduction reaction, and particularly, a metal oxide (Ag ₂ O,
PbO, NiO, Ni ₂ O ₃ , CoO, Co ₂ O ₃ , Co ₃
O ₄ , CuO, Cu ₂ O, Bi ₂ O ₃ , Sb ₂ O ₃ , Cr
₂ O ₃ , MnO ₂ , Fe ₃ O ₄ ), metal sulfide (Ag ₂ S, P
bS, NiS, Ni ₂ S, Ni ₃ S ₄ , CoS, Co ₂ S ₃ ,
Co ₃ S ₄ , CuS, Cu ₂ S, Bi ₂ S ₃ , Sb ₂ S ₃ , S
b ₂ S ₄ , Sb ₂ S ₅ , CrS, Cr ₂ S ₃ , MnS, Mn ₃
S ₄ , MnS ₂ , FeS, Fe ₂ S ₃ , FeS ₂ , Mo
₂ S ₃ , MoS ₂ ), metal selenide (Ag ₂ Se, PbS)
e, Co ₂ Se ₃ , Co ₃ Se ₄ , CuSe, Cu ₂ Se,
Bi ₂ Se ₃ , Sb ₂ Se ₃ , Sb ₂ Se ₅ , Cr ₂ Se ₃ ),
Metal telluride (Ag ₂ Te, PbTe, NiTe, N
i ₂ Te ₃ , CuTe, Cu ₂ Te, Bi ₂ Te ₃ , Sb ₂ T
e ₃ ) Either or a mixture can provide a high effect.

The amount of the compound added is desirably about the same as the difference in the irreversible capacity of the positive and negative electrodes in terms of electric capacity, and is 0.2% to 15% based on the total amount of the carbonaceous material and the compound as the negative electrode active material. %, The effect can be exhibited most.

The conductive agent for the negative electrode used in the present invention may be any material as long as it is an electron conductive material. For example, graphites such as natural graphite (flaky graphite etc.), artificial graphite, expanded graphite, carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fibers, Conductive fibers such as metal fibers, metal powders such as copper and nickel, and organic conductive materials such as polyphenylene derivatives can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite, acetylene black and carbon fiber are particularly preferred. The addition amount of the conductive agent is not particularly limited, but may be 1 to 50 with respect to the negative electrode material.
% By weight, and particularly preferably 1 to 30% by weight. In addition, the negative electrode material of the present invention has electron conductivity itself, and furthermore, the additive reacts with lithium at the first charge to become a metal conductor, so that it is possible to function as a battery without adding a conductive material. It is.

The binder for the negative electrode used in the present invention may be either a thermoplastic resin or a thermosetting resin. Preferred binders in the present invention include, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexa Fluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetra Fluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene Polymer, ethylene - chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene copolymer, vinylidene fluoride - perfluoromethyl vinyl ether - tetrafluoroethylene copolymer,
Ethylene-acrylic acid copolymer or (Na
⁺ ) Ion crosslinked product, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl methacrylate Copolymers or (Na ⁺ ) ion crosslinked products of the above materials can be mentioned, and these materials can be used alone or as a mixture. Further, a more preferable material among these materials is
Styrene butadiene rubber, polyvinylidene fluoride, ethylene-acrylic acid copolymer or (Na ⁺ )
Ion crosslinked product, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl methacrylate copolymer It is a combined or (Na ⁺ ) ion crosslinked product of the above materials.

As the current collector for the negative electrode used in the present invention, any current collector that does not cause a chemical change in the constructed battery may be used. For example, in addition to stainless steel, nickel, copper, titanium, carbon, conductive resin, and the like, a material obtained by treating the surface of copper or stainless steel with carbon, nickel, or titanium is used. Particularly, copper or a copper alloy is preferable. The surface of these materials can be oxidized and used. In addition, it is desirable to make the current collector surface uneven by surface treatment. As the shape, in addition to a foil, a film, a sheet, a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are used. The thickness is not particularly limited, but 1 to
Those having a size of 500 μm are used.

The positive electrode active material is a lithium-containing metal compound, and may be any compound that releases and occludes lithium ions.

For example, Li _x CoO ₂ , Li _x NiO ₂ , L
_{i x MnO 2, Li x Co} y Ni 1-y O 2, Li x Co y M 1-y
_{O z, Li x Ni 1-} y M y O z, Li x Mn 2 O 4, Li x Mn
_{2-y MyO 4} (M = Na, Mg, Sc, Y, Mn, Fe,
Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, B
At least one), (where x = 0 to 1.2, y
= 0-0.9, z = 2.0-2.3). Here, the above-mentioned x value is a value before the start of charge / discharge, and increases / decreases due to charge / discharge. However, a transition metal chalcogenide, a lithium compound of vanadium oxide, and a lithium compound of niobium oxide can also be used. It is also possible to use a mixture of a plurality of different positive electrode materials. Although the average particle diameter of the positive electrode active material particles is not particularly limited,
It is preferably from 30 to 30 μm.

The present invention is particularly effective for compounds in which the charge / discharge efficiency of the positive electrode active material (absorption / release amount × 100 (%)) is in the range of 75 to 95%.

In particular, the positive electrode active material is Li _x Ni _{1 -y My}
O _z , (M = Na, Mg, Sc, Y, Mn, Fe, C
o, Ni, Cu, Zn, Al, Cr, Pb, Sb, B) (where x = 0 to 1.2, y =
0 to 0.9, z = 2.0 to 2.3), the irreversible capacity is large in the case of a lithium-containing nickel oxide,
The effect of the present invention is great.

Such Li _x Ni _{1- y My} O _z , (M = N
a, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu,
(At least one of Zn, Al, Cr, Pb, Sb, and B), (where x = 0 to 1.2, y = 0 to 0.9, z =
The lithium-containing nickel oxide represented by 2.0 to 2.3) is more effective when synthesized in a temperature range of 750 ° C to 900 ° C.

The conductive agent for the positive electrode used in the present invention may be any electronic conductive material that does not cause a chemical change at the charge / discharge potential of the positive electrode material used. For example, graphites such as natural graphite (flaky graphite, etc.), artificial graphite, acetylene black, Ketjen black, channel black, furnace black, lamp black,
Carbon blacks such as thermal black, carbon fiber,
Conductive fibers such as metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide and organic conductive materials such as polyphenylene derivatives Materials and the like can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite and acetylene black are particularly preferred. The addition amount of the conductive agent is not particularly limited, but is preferably 1 to 50% by weight, and particularly preferably 1 to 30% by weight based on the positive electrode material. For carbon and graphite, 2 to 15% by weight is particularly preferred.

The positive electrode binder used in the present invention may be either a thermoplastic resin or a thermosetting resin. Preferred binders in the present invention include, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene -Hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene -Tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene Polymer, ethylene - chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene copolymer, vinylidene fluoride - perfluoromethyl vinyl ether - tetrafluoroethylene copolymer,
Ethylene-acrylic acid copolymer or (Na
⁺ ) Ion crosslinked product, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl methacrylate Copolymers or (Na ⁺ ) ion crosslinked products of the above materials can be mentioned, and these materials can be used alone or as a mixture. Among these materials, more preferred materials are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

The positive electrode current collector used in the present invention may be any electronic conductor that does not cause a chemical change in the charge and discharge potential of the positive electrode material used. For example, in addition to stainless steel, aluminum, titanium, carbon, conductive resin, and the like, a material obtained by treating the surface of aluminum or stainless steel with carbon or titanium is used. Particularly, aluminum or an aluminum alloy is preferable. The surface of these materials can be oxidized and used. In addition, it is desirable to make the current collector surface uneven by surface treatment. The shape is a foil, a film,
A sheet, a net, a punched material, a lath body, a porous body, a foamed body, a fiber group, a molded body of a nonwoven fabric, and the like are used. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.

As the electrode mixture, a filler, a dispersant, an ionic conductor, a pressure enhancer and other various additives can be used in addition to a conductive agent and a binder. As the filler, any fibrous material that does not cause a chemical change in the configured battery can be used. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. The addition amount of the filler is not particularly limited, but is 0 to 30% by weight based on the electrode mixture.
Is preferred.

The structure of the negative electrode plate and the positive electrode plate in the present invention is as follows.
It is preferable that the negative electrode mixture surface exists at least on the surface opposite to the positive electrode mixture surface.

The non-aqueous electrolyte used in the present invention comprises a solvent and a lithium salt dissolved in the solvent. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC).
Cyclic carbonates such as dimethyl carbonate (D
MC), linear carbonates such as diethyl carbonate (DEC), ethyl methyl carbonate (EMC) and dipropyl carbonate (DPC), and aliphatic carboxylic esters such as methyl formate, methyl acetate, methyl propionate and ethyl propionate. , Γ-lactones such as γ-butyrolactone, 1,2-dimethoxyethane (DM
E), chain ethers such as 1,2-diethoxyethane (DEE) and ethoxymethoxyethane (EME), cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolan, formamide, Acetamide, dimethylformamide, dioxolan, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methylsulfolane, 1,3-dimethyl-2-
Aprotic organic solvents such as imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propanesultone, anisole, dimethylsulfoxide, N-methylpyrrolidone; Can be used alone or in combination of two or more. Among them, a mixed system of a cyclic carbonate and a chain carbonate or a mixed system of a cyclic carbonate, a chain carbonate and an aliphatic carboxylic acid ester is preferable.

As a lithium salt dissolved in these solvents,
Is, for example, LiClO_Four , LiBF _Four, LiPF₆, Li
AlCl_Four, LiSbF₆, LiSCN, LiCl, Li
CF _ThreeSO_Three , LiCF_ThreeCO_Two , Li (CF_ThreeS
O_Two)_Two, LiAsF₆ , LiN (CF_ThreeSO_Two)_Two, Li
B_TenCl_Ten, Lithium lower aliphatic carboxylate, LiC
1, LiBr, LiI, lithium chloroborane,
Lithium nylborate, imides and the like,
These may be used alone or in combination of two or more
It is possible to use⁶Contains
More preferably.

A particularly preferred non-aqueous electrolyte in the present invention is an electrolyte containing at least ethylene carbonate and ethyl methyl carbonate and LiPF ₆ as a supporting salt. The amount of these electrolytes to be added to the battery is not particularly limited, but a required amount can be used depending on the amounts of the positive electrode material and the negative electrode material and the size of the battery. The amount of the supporting electrolyte dissolved in the nonaqueous solvent is not particularly limited.
2-2 mol / l is preferred. In particular, 0.5-1.5m
ol / l is more preferable.

In addition to the electrolyte, the following solid electrolytes are also used.
Can be used. As solid electrolyte, inorganic solid electrolyte
It can be divided into decomposition and organic solid electrolyte. For inorganic solid electrolyte
Is often Li nitride, halide, oxyacid salt, etc.
Are known. Above all, Li_FourSiO_Four, Li_FourSiO_Four
-LiI-LiOH,_xLi_ThreePO_Four−_(1-x)Li_FourSi
O _Four, Li_TwoSiS_Three, Li_ThreePO_Four−Li_TwoS-SiS_Two,
Phosphorus sulfide compounds are effective. With organic solid electrolyte
Is, for example, polyethylene oxide, polypropylene
Oxide, polyphosphazene, polyaziridine, poly
Ethylene sulfide, polyvinyl alcohol, poly
Such as vinylidene chloride and polyhexafluoropropylene
Polymer materials such as derivatives, mixtures and composites
It is effective.

It is also effective to add another compound to the electrolyte for the purpose of improving the discharge and charge / discharge characteristics.
For example, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, pyridine, hexaphosphoric triamide, nitrobenzene derivative, crown ethers, quaternary ammonium salt, ethylene glycol dialkyl ether and the like can be mentioned.

As the separator used in the present invention,
Has a large ion permeability, has a predetermined mechanical strength,
An insulating microporous thin film is used. Further, it is preferable to have a function of closing a hole at a certain temperature or higher to increase resistance. Sheets, nonwoven fabrics or woven fabrics made from olefin polymers such as polypropylene and polyethylene alone or in combination or glass fibers are used because of their organic solvent resistance and hydrophobicity. The pore diameter of the separator is desirably in a range in which the positive and negative electrode materials detached from the electrode sheet, the binder, and the conductive agent do not pass.
A thickness of 1 μm is desirable. Generally, the thickness of the separator is 10 to 300 μm. The porosity is determined according to the electron and ion permeability, the material, and the film pressure, but is generally preferably 30 to 80%.

Further, a mixture of a polymer material and an organic electrolyte composed of a solvent and a lithium salt dissolved in the solvent is absorbed and held in the positive electrode mixture and the negative electrode mixture. It is also possible to configure a battery in which a porous separator made of a retained polymer is integrated with a positive electrode and a negative electrode. As the polymer material, any material can be used as long as it can absorb and hold an organic electrolytic solution, and a copolymer of vinylidene fluoride and hexafluoropropylene is particularly preferable.

The shape of the battery can be any of a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square type, and a large type used for electric vehicles.

Further, the non-aqueous electrolyte secondary battery of the present invention can be used for a portable information terminal, a portable electronic device, a small household power storage device,
The present invention can be used for a motorcycle, an electric vehicle, a hybrid electric vehicle, and the like, but is not particularly limited thereto.

[0082]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

Example 1 Method for Producing Positive Electrode A nickel sulfate solution, a cobalt sulfate solution was introduced into a container at a constant flow rate using nickel sulfate, cobalt sulfate, and sodium hydroxide solutions, and sodium hydroxide was sufficiently stirred. The solution was added.

The resulting precipitate was washed with water and dried to obtain a nickel-cobalt coprecipitated hydroxide. The chemical composition of the obtained nickel-cobalt coprecipitated hydroxide is Ni _0.85 Co _0.15
(OH) ₂ .

The obtained nickel-cobalt coprecipitated hydroxide and lithium hydroxide were mixed, and mixed under an oxidizing atmosphere.
By baking at 00 ° C. for 10 hours, LiNi _0.85 Co _0.15 O ₂ was synthesized.

The positive electrode plate 5 is made of LiN synthesized by the above method.
i _0.85 Co _0.15 O ₂ , 85% by weight, 10% by weight of carbon powder as a conductive agent, and polyvinylidene fluoride resin 5 as a binder
% By weight, and these were dispersed in dehydrated N-methylpyrrolidinone to prepare a slurry, applied on a positive electrode current collector made of aluminum foil, dried, and then rolled.

The method of manufacturing the negative electrode (Table 1) shows the components (simple element, intermetallic compound, solid solution) of the solid phase A and the solid phase B of the negative electrode material (material A to material G) used in this example, and Shows the element ratio, the melting temperature, and the solidus temperature. In this embodiment, a specific manufacturing method will be described below.

A powder or a block of each element constituting the negative electrode material is put into a melting tank at a charging ratio shown in (Table 1), melted at a melting temperature shown in (Table 1), and the melt is rapidly cooled by a roll. The mixture was quenched and solidified by a method to obtain a solidified product. continue,
The coagulated material was subjected to a heat treatment for 20 hours in an inert atmosphere at a temperature lower by about 10 ° C. to 50 ° C. than the solidus temperature of the solid solution or the intermetallic compound determined from the charged composition shown in Table 1.
The heat-treated product was pulverized by a ball mill and classified by a sieve to obtain materials A to G in particles of 45 μm or less. From these electron microscopic observation results, it was confirmed that the entire surface or a part of the periphery of the solid phase A particles was covered with the solid phase B.

[0089]

[Table 1]

The negative electrode plate 6 is made of the obtained negative electrode materials A to G10.
After adding 3.36% by weight of NiO as a metal oxide with respect to the total amount of the negative electrode material and the additive to 0 parts by weight, 20 parts by weight of carbon powder as a conductive agent and polyvinylidene fluoride resin 5 as a binder were added. Parts by weight and dehydrated N-
A slurry was prepared by being dispersed in methylpyrrolidinone, applied on a negative electrode current collector made of copper foil, dried, and then rolled.

FIG. 3 is a longitudinal sectional view of the cylindrical battery according to the present invention. The positive electrode plate 5 and the negative electrode plate 6 are spirally wound a plurality of times via a separator 7 and housed in the battery case 1. Then, from the positive electrode plate 5, a positive electrode lead 5a is provided.
Is pulled out and connected to the sealing plate 2, and the negative electrode lead 6 a is pulled out from the negative electrode plate 6 and connected to the bottom of the battery case 1. The battery case and the lead plate can be made of a metal or an alloy having an organic electrolyte resistance and electron conductivity.
For example, iron, nickel, titanium, chromium, molybdenum,
Metals such as copper and aluminum or alloys thereof are used. In particular, the battery case is made of stainless steel plate, Al-
A processed Mn alloy plate, most preferably aluminum for the positive electrode lead and nickel for the negative electrode lead. Further, as the battery case, various types of engineering plastics and a combination thereof with a metal can be used to reduce the weight. Reference numeral 8 denotes an insulating ring provided on the upper and lower portions of the electrode plate group 4, respectively. Then, an electrolytic solution is injected, and a battery can is formed using the sealing plate. At this time, the safety valve can be used as a sealing plate. In addition to the safety valve, various conventionally known safety elements may be provided. For example, fuses, bimetals, P
A TC element or the like is used. In addition to the safety valve, as a countermeasure against an increase in the internal pressure of the battery case, a method of making a cut in the battery case, a gasket cracking method, a sealing plate cracking method, or a cutting method with a lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures for overcharging and overdischarging, or may be connected independently. As a measure against overcharging, a method of interrupting the current by increasing the internal pressure of the battery can be provided. At this time, a compound for increasing the internal pressure can be contained in the mixture or the electrolyte. Compounds for increasing the internal pressure include Li ₂ CO ₃ , LiHCO ₃ , Na ₂ CO ₃ , NaHCO ₃ ,
Carbonates such as CaCO ₃ and MgCO ₃ ;
Cap, battery case, sheet, lead plate welding method,
Known methods (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used. A conventionally known compound or mixture such as asphalt can be used as the sealing agent for closing.

As the organic electrolyte, a solution obtained by dissolving 1.5 mol / l of LiPF ₆ in a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 1 was used.

As described above, the materials A to G shown in Table 2
Batteries 1 to 7 were prepared using as a negative electrode. The manufactured cylindrical battery had a diameter of 18 mm and a height of 650 mm. These batteries were charged at a constant current of 100 mA until the voltage reached 4.1 V, and then a charge / discharge cycle in which the batteries were discharged at a constant current of 100 mA until the voltage reached 2.0 V was repeated. Charge and discharge were performed in a constant temperature bath at 20 ° C. The charge / discharge was repeated up to 100 cycles, and 10 times the initial discharge capacity.
Table 2 shows the ratio of the discharge capacity at the 0th cycle as the capacity retention ratio.

Comparative Example 1 As Comparative Example 1, a battery was constructed in the same manner as in Example 1, except that graphite was used for the negative electrode and NiO was added as an additive at 3.10% with respect to the total amount of the negative electrode material and the additive. The battery in Comparative Example 1 was Battery 8.

Comparative Example 2 As Comparative Example 2, a battery was constructed in the same manner as in Example 1 except that materials A to G were used as the negative electrode material and no additive was added. The batteries in Comparative Example 2 were referred to as batteries 9 to 15.

[0096]

[Table 2]

From the results shown in Table 2, the batteries 1 to 7 of Example 1 using the composite particles of the present invention and the negative electrode active material were the same as those of Comparative Example 1.
It can be seen that the battery discharge capacity is significantly larger than that of the battery 8 using graphite as a conventional negative electrode material shown in FIG.

Thus, a high capacity lithium secondary battery can be realized by using the composite particles of the present invention.

The batteries 1 to 7 of Example 1 have improved cycle characteristics as compared with the batteries 9 to 15 of Comparative Example 2, and the cycle characteristics can be improved by adding an additive to the negative electrode. You can see that.

This is because even if the capacity of the battery itself is the same, the irreversible capacity of the positive electrode (capacity of A in FIG. 1) is the load of the negative electrode, so that the charge exceeds the reversible charge / discharge capacity of the negative electrode. It was considered that the discharge capacity decreased due to the lithium precipitation reaction on the composite particles because the battery was charged.

If the load on the negative electrode is reduced by reducing the amount of the positive electrode or the charging voltage in the battery, a battery having good cycle characteristics can be realized. In this case, however, the discharge capacity itself is reduced, and the battery has a high capacity. Cannot be realized.

On the other hand, in the batteries 1 to 7 of the present invention, the reversible capacity of the positive electrode and the reversible capacity of the negative electrode are reduced because the compound having a capacity corresponding to A that cannot participate in charge / discharge is consumed (capacity B in FIG. 2). A battery that can be used to the maximum and has a good cycle life can be obtained. As a result, it is considered that the discharge capacity and the cycle characteristics were improved.

Example 2 As Example 2, a composite was formed on the negative electrode.
Using particle material C, oxide Ag as an additive_TwoO, Pb
O, Ni_TwoO_Three, CoO, Co_TwoO_Three, Co_ThreeO_Four, CuO,
Cu_TwoO, Bi_TwoO _Three, Sb_TwoO_Three, Cr_TwoO_Three, MnO_Two, F
e_ThreeO_Four9.06,8.75,6.6 with respect to the total amount of the negative electrode material and additives
5,3.11,6.65,10.31,3.30,5.94,16.67,11.11,6.12,6.95
A battery was constructed in the same manner as in Example 1 except that the weight% was added.
Was. The batteries in Example 2 were batteries 40 to 53.

Example 3 As Example 3, a composite was formed on the negative electrode.
Using particle material C, metal sulfide Ag as an additive _TwoS,
PbS, NiS, Ni_TwoS, Ni_ThreeS_Four, CoS, Co_TwoS
_Three, Co_ThreeS_Four, CuS, Cu_TwoS, Bi_TwoS_Three, Sb_TwoS_Three,
Sb_TwoS_Four, Sb_TwoS_Five, CrS, Cr_TwoS_Three, MnS, Mn
_ThreeS_Four, MnS_Two, FeS, Fe_TwoS_Three, FeS_Two, Mo
_TwoS_Three, MoS_TwoThe total amount of the composite particle material and additive respectively
9.71,9.38,3.56,2.93,2.98,3.57,2.8,2.99,3.75,
6.24,6.72,4.44,3.64,3.17,3.30,2.62,3.41,2.87,2.33,
Example except that 3.45,2.72,2.35,3.76,3.14% by weight was added
A battery was constructed in the same manner as in Example 1. Battery in Example 3 above
Were designated as batteries 54 to 77.

Example 4 In Example 4, a composite particle material C was used for the negative electrode, and a metal selenide Ag ₂ was used as an additive.
Se, PbSe, Co ₂ Se ₃ , Co ₃ Se ₄ , CuSe,
Cu ₂ Se, Bi ₂ Se ₃ , Sb ₂ Se ₃ , Sb ₂ Se ₅ , C
r ₂ Se ₃ with respect to the total amount of the composite particle material and the additive, respectively
11.55, 11.22, 4.64, 4.83, 5.59, 8.08, 8.56, 6.28,
A battery was constructed in the same manner as in Example 1 except that 5.00 and 4.45% by weight were added. The batteries in Example 4 were batteries 78 to 87.

Example 5 In Example 5, a composite particle material C was used for the negative electrode, and a metal telluride Ag ₂ was used as an additive.
_{Te, PbTe, NiTe, Ni 2} Te 3, CuTe, C
u ₂ Te, Bi ₂ Te ₃ , and Sb ₂ Te ₃ were respectively 13.46, 13.12, 7.30, 6.54,
Example 1 except that 7.49, 9.98, 10.46 and 8.8% by weight were added.
A battery was constructed in the same manner as described above. The batteries in Example 5 were referred to as batteries 88 to 95.

The amount of each substance added is calculated from the theoretical capacity so that the sum of the electric capacity consumed in the reduction reaction of each substance and the irreversible capacity of the composite particles as the negative electrode material is equal to the irreversible capacity of the positive electrode. Was added.

Table 2 shows the ratio of the discharge capacity at the 100th cycle to the initial discharge capacity and the initial discharge capacity of the batteries tested in Examples 2 to 4 as a capacity retention ratio in Table 2 (Table 3).

[0109]

[Table 3]

Similar effects were obtained with other metal oxides, metal sulfides, metal selenides, and metal tellurides which are the additives of the present invention, similarly to NiO added in Example 1.

As described above, by using the additive of the present invention in combination with the composite particles, a battery having high capacity and good cycle characteristics can be realized.

The amount of electricity charged when reacting with lithium ions by a reduction reaction can be measured by the following method.

Acetylene black at a weight ratio of about 30% is added to a compound to be added (eg, NiS), mixed and then pelletized at 250 kg / cm ² to be fixed to a stainless steel current collector to be used as a working electrode.

Using metal lithium for the counter electrode and the reference electrode,
Discharge at a constant current until the voltage reaches 0 V with respect to the lithium electrode, and measure the quantity of electricity. The electrolyte used for the measurement is most preferably used for a battery. The current density during charging is 0.1
Desirably, it is mA / cm ² or less.

In this example, Li was used as the positive electrode active material.
Although Ni _x Co _{1 -x} O ₂ was used, the positive electrode active material was a lithium-containing metal compound, and the charge-discharge efficiency (storage amount / release amount × 100 (%)) of releasing and occluding lithium ions was 75 to 75%.
In the range of 95%, the same effect can be obtained since the operating principle of the battery is the same.

Further, in particular, Li _x Ni _1-y which is a positive electrode active material
M _y O _z, (where x = 0~1.2, y = 0~0.9, z
= 2.0-2.3) Co was used as the substitution metal M. In addition, M = Na, Mg, Sc, Y, Mn, Fe, C
The effect is great when at least one of u, Zn, Al, Cr, Pb, Sb, and B is used.

[0117]

As is apparent from the above description, the negative electrode according to the present invention (composite particles in which the whole or a part of the periphery of the core particle composed of the solid phase A is coated with the solid phase B, and the solid phase A is The solid phase B containing at least tin as a constituent element;
Is selected from the group consisting of tin, which is a constituent element of the solid phase A, and a group 2 element, a transition element, a group 12, a group 13 element, and a group 14 element except carbon, excluding the above-mentioned constituent elements. A metal oxide (Ag ₂ O, PbO, NiO, Ni ₂ O ₃ ) is used as a compound which irreversibly reacts with lithium ions by a reduction reaction using a solid solution with at least one element or a material which is an intermetallic compound) as a negative electrode main material. , CoO, C
o ₂ O ₃ , Co ₃ O ₄ , CuO, Cu ₂ O, Bi ₂ O ₃ , Sb ₂
O ₃ , Cr ₂ O ₃ , MnO ₂ , Fe ₃ O ₄ ), metal sulfide (A
g ₂ S, PbS, NiS, Ni ₂ S, Ni ₃ S ₄ , CoS,
Co ₂ S ₃ , Co ₃ S ₄ , CuS, Cu ₂ S, Bi ₂ S ₃ , S
b ₂ S ₃ , Sb ₂ S ₄ , Sb ₂ S ₅ , CrS, Cr ₂ S ₃ , Mn
S, Mn ₃ S ₄ , MnS ₂ , FeS, Fe ₂ S ₃ , FeS ₂ ,
Mo ₂ S ₃ , MoS ₂ ), metal selenide (Ag ₂ Se, P
bSe, Co ₂ Se ₃ , Co ₃ Se ₄ , CuSe, Cu ₂ S
e, Bi ₂ Se ₃ , Sb ₂ Se ₃ , Sb ₂ Se ₅ , Cr ₂ S
e ₃ ), metal telluride (Ag ₂ Te, PbTe, NiT)
e, Ni ₂ Te ₃ , CuTe, Cu ₂ Te, Bi ₂ Te ₃ ,
By adding at least one or a mixture selected from the group consisting of Sb ₂ Te ₃ ), a non-aqueous electrolyte secondary battery having a high capacity and an excellent cycle life can be provided.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a first charge / discharge of a lithium secondary battery when the present invention is not used.

FIG. 2 is a conceptual diagram of the first charge / discharge of the lithium secondary battery of the present invention.

FIG. 3 is a longitudinal sectional view of a cylindrical battery in the present example and a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Sealing plate 3 Insulating packing 4 Electrode plate group 5 Positive electrode plate 5a Positive electrode lead 6 Negative electrode plate 6a Negative electrode lead 7 Separator 8 Insulating ring

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Harari Shimamura 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshiaki Nitta 1006 Odaka Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co. F term (for reference) 5H003 AA02 AA04 BA01 BA03 BA07 BB02 BB04 BB05 BC01 BC05 BD00 BD03 BD04 5H014 AA02 AA06 BB01 BB06 BB08 BB12 CC01 EE05 EE08 EE10 HH01 HH04 5H029 AJ03 A04 AM04 AM03 AM02 DJ09 DJ16 HJ00 HJ02 HJ19

Claims (11)

[Claims] 1. A non-aqueous electrolyte secondary battery comprising a positive electrode capable of charging and discharging lithium and a negative electrode via a separator or a solid electrolyte layer impregnated with an organic electrolytic solution,
The negative electrode is a composite particle in which the whole or a part of the periphery of the core particle composed of the solid phase A is coated with the solid phase B. The solid phase A contains at least tin as a constituent element,
Is selected from the group consisting of tin, which is a constituent element of the solid phase A, and a group 2 element, a transition element, a group 12, a group 13 element, and a group 14 element excluding carbon except for the above-mentioned constituent elements. A non-aqueous electrolyte comprising a solid solution with at least one element or a material that is an intermetallic compound and using a mixture to which a compound of the metal, which is electrochemically reduced to a metal by charging a negative electrode, is added. Next battery. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the metal compound added to and mixed with the negative electrode material is at least one selected from metal oxides, metal sulfides, metal selenides, and metal tellurides. . 3. The metal oxide to be added to and mixed with the negative electrode material is Ag ₂ O, PbO, NiO, Ni ₂ O ₃ , CoO, C
o ₂ O ₃ , Co ₃ O ₄ , CuO, Cu ₂ O, Bi ₂ O ₃ , Sb _{2
O 3, Cr 2 O 3,} MnO 2, Fe 3 non-aqueous electrolyte secondary battery according to claim 1, wherein O is at least one selected from the group consisting of _4. 4. The metal sulfide added to and mixed with the negative electrode material is Ag ₂ S, PbS, NiS, Ni ₂ S, Ni ₃ S ₄ , C
oS, Co ₂ S ₃ , Co ₃ S ₄ , CuS, Cu ₂ S, Bi ₂ S
_{3, Sb 2 S 3, Sb} 2 S 4, Sb 2 S 5, CrS, Cr
₂ S ₃ , MnS, Mn ₃ S ₄ , MnS ₂ , FeS, Fe
_{2 S 3, FeS 2, Mo} 2 S 3, the non-aqueous electrolyte secondary battery according to claim 1, wherein at least one selected from the group consisting of MoS _2. 5. The metal selenide to be added to and mixed with the negative electrode material is Ag ₂ Se, PbSe, Co ₂ Se ₃ , or Co ₃ S.
e ₄ , CuSe, Cu ₂ Se, Bi ₂ Se ₃ , Sb ₂ Se ₃ ,
Sb ₂ Se _5, Cr ₂ non-aqueous electrolyte secondary battery according to claim 1, wherein Se is at least one selected from the group consisting of _3. 6. Metal telluride added to and mixed with a negative electrode material
Things are Ag_TwoTe, PbTe, NiTe, Ni_TwoTe_Three,
CuTe, Cu_TwoTe, Bi_TwoTe_Three, Sb_TwoTe _ThreeFrom
The at least one member selected from the group consisting of
Non-aqueous electrolyte secondary battery. 7. The method according to claim 1, wherein the amount of the metal compound added to and mixed with the main material of the negative electrode is a value corresponding to the difference between the irreversible capacities of the positive electrode and the negative electrode which cannot contribute to the initial discharge after the first charge of the positive electrode and the negative electrode. Item 3. A non-aqueous electrolyte secondary battery according to Item 2. 8. The method according to claim 2, wherein the content of the metal oxide added to and mixed with the main material of the negative electrode is in the range of 0.2% to 20% with respect to the sum of the carbon material and the metal compound. Non-aqueous electrolyte secondary battery. 9. A compound capable of charging and discharging lithium used for a positive electrode is represented by a general formula Li _x Ni _{1- y My} O _z , (M = Na, M
g, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn,
Al, Cr, Pb, Sb, at least one of B),
(Where x = 0 to 1.2, y = 0 to 0.9, z = 2.0
To 2.3) a lithium-containing metal compound represented by the formula (1):
The non-aqueous electrolyte secondary battery according to the above. 10. An initial charge / discharge efficiency in which a lithium-containing metal compound used for a positive electrode releases lithium ions upon first charging and occludes lithium ions upon initial discharging is obtained (storage amount / release amount × 100 (%)). The non-aqueous electrolyte secondary battery according to claim 1, wherein (b) is in the range of 75 to 95%. 11. The non-aqueous electrolyte secondary battery according to claim 9, wherein the lithium-containing metal oxide used for the positive electrode is obtained by mixing lithium hydroxide with a hydroxide of the metal and synthesizing the mixture by heating.