JP7227477B2 - thin film lithium secondary battery - Google Patents

Description

The present invention relates to a thin film lithium secondary battery.

Small-capacity thin-film secondary batteries have been developed as backup power sources for small electronic devices, IC cards, and the like (for example, Patent Documents 1 to 3). As the thin film secondary battery, a thin film lithium secondary battery using lithium ions is mainly used. The thin-film lithium secondary battery has a positive electrode layer made of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ or the like, an electrolyte layer made mainly of Li ₃ PO ₄ +N (LiPON), and a negative electrode layer made of Li metal, V _{2 .} It is made of O ₅ , Nb ₂ O ₅ , In ₂ O ₃ or the like.

JP 2005-251417 A WO2002/089236 WO2011/018980

A conventional thin-film lithium secondary battery has a problem that even if the film thickness of the positive electrode layer and the negative electrode layer is increased, the charge/discharge capacity is not so large. The reason why the charge/discharge capacity does not increase is that when the film thickness of the positive electrode layer and the negative electrode layer is increased, the internal resistance increases and the movement of lithium ions slows down. In addition, since the thin-film lithium secondary battery in which the thickness of the positive electrode layer and the negative electrode layer is thick has a large internal resistance, there is a problem that the charging/discharging capacity is lowered when the charging/discharging is performed with a large current.

The present invention is a thin-film lithium secondary battery that can increase the charge-discharge capacity by increasing the thickness of the positive electrode layer and/or the negative electrode layer, and has little decrease in the charge-discharge capacity even when charging and discharging at a large current. An object of the present invention is to provide a secondary battery.

A thin film lithium secondary battery according to a first aspect of the present invention comprises a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, the positive electrode layer and/or the negative electrode layer containing nitrogen (N).

In the thin film lithium secondary battery according to the second aspect of the present invention, in contrast to the first aspect, the positive electrode layer contains lithium-manganese oxide, lithium-cobalt oxide, or lithium-manganese-cobalt oxide. , the negative electrode layer includes niobium oxide or lithium-titanium oxide, and the solid electrolyte layer includes LiPON in which nitrogen (N) is added to lithium phosphate.

According to the first and second aspects of the present invention, by providing the positive electrode layer and/or the negative electrode layer doped with nitrogen, the ion conductivity of the positive electrode layer and/or the negative electrode layer is improved, Even if the film thickness of the positive electrode layer and/or the negative electrode layer is increased, an increase in internal resistance is suppressed. Therefore, since lithium ions can smoothly move in the thickness direction of the positive electrode layer and/or the negative electrode layer, the thin film lithium secondary battery can have a large charging/discharging capacity. In addition, since the thin-film lithium secondary battery has a small internal resistance, even if it is charged and discharged with a large current, the charge-discharge capacity does not decrease much.

1 is a longitudinal sectional view schematically showing a thin film lithium secondary battery according to this embodiment; FIG. 4 is a graph showing voltage-charge/discharge capacity characteristics of a thin film lithium secondary battery according to an example. 4 is a graph showing cycle characteristics of thin-film lithium secondary batteries according to examples.

A thin film lithium secondary battery according to the present invention comprises a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, wherein the positive electrode layer and/or the negative electrode layer contain nitrogen (N). That is, in the thin film lithium secondary battery, the positive electrode layer or the negative electrode layer may contain N, or both the positive electrode layer and the negative electrode layer may contain N. In the thin film lithium secondary battery, the ion conductivity of the positive electrode layer and/or the negative electrode layer is improved, and the charge/discharge capacity can be increased by increasing the film thickness of the positive electrode layer and/or the negative electrode layer. .

The thin-film lithium secondary battery includes a case comprising a positive electrode current collector layer, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector layer. In this case, the thin film lithium secondary battery is preferably provided on the substrate. The thin-film lithium secondary battery has a positive electrode current collector layer, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector layer in this order from the side in contact with the substrate. A case where a negative electrode current collector layer, a negative electrode layer, a solid electrolyte layer, a positive electrode layer, and a positive electrode current collector layer are provided in this order from the side is included. The thin-film lithium secondary battery may use the positive electrode current collector layer or the negative electrode current collector layer as a substrate, and in this case, the substrate can be omitted.

In addition, the positive electrode current collector layer and the negative electrode current collector layer are not necessarily required. For example, the positive electrode layer may also serve as the positive electrode current collector layer, and the negative electrode layer may also serve as the negative electrode current collector layer. . That is, the positive electrode layer and the positive electrode current collector layer include the case where they are integrally formed as a single layer. Moreover, the negative electrode layer and the negative electrode current collector layer include the case where they are integrally formed as a single layer.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A thin-film lithium secondary battery 10 shown in FIG. The thin film lithium secondary battery 10 is provided on a substrate 12, and from the side in contact with the substrate 12, a positive electrode current collector layer 14, a positive electrode layer 16, a solid electrolyte layer 18, a negative electrode layer 20, and a negative electrode current collector. Layers 22 are provided in sequence.

A positive collector layer 14 is provided on the surface of the substrate 12 . A positive electrode layer 16 is provided on the surface of the positive electrode current collector layer 14 . The positive electrode collector layer 14 and the positive electrode layer 16 are electrically connected. A solid electrolyte layer 18 is provided on the surface of the positive electrode layer 16 , and a negative electrode layer 20 is provided on the opposite side of the solid electrolyte layer 18 . A negative electrode collector layer 22 is provided on the surface of the negative electrode layer 20 . The negative electrode layer 20 and the negative electrode collector layer 22 are electrically connected.

A heat-resistant substrate or a flexible resin substrate can be used for the substrate 12 . The material of the substrate having heat resistance can be selected from, for example, glass, silicon (Si), ceramics, stainless steel, and the like. Materials for the flexible resin substrate can be selected from, for example, polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), and the like.

The positive electrode current collector layer 14 and the negative electrode current collector layer 22 are made of a metal with low resistance, that is, a conductor, and may be made of the same material or different materials. Materials for the positive electrode current collector layer 14 and the negative electrode current collector layer 22 are preferably selected from, for example, titanium (Ti), vanadium (V), copper (Cu), aluminum (Al), and the like.

The positive electrode layer 16 contains lithium (Li), is made of a material capable of intercalating lithium and desorbing the intercalated lithium, and further contains nitrogen. The positive electrode layer 16 is made of, for example, lithium-cobalt oxide (LiCoO ₂ ), lithium-nickel oxide (LiNiO ₂ ), lithium-manganese oxide (Li ₂ Mn ₂ O ₄ , LiMn ₂ O ₄ ), lithium-manganese- Metal oxides containing Li, such as cobalt oxides (LiMnCoO ₄ ), are doped with N. The doping amount of N in the positive electrode layer 16 is preferably 0.1 at % to 10.0 at %, more preferably 1.0 at % to 5.0 at %. By setting the doping amount of N to 0.1 at % or more, the effect of improving the ionic conductivity can be obtained more reliably. When the doping amount of N exceeds 10.0 atomic %, the effect of improving the ionic conductivity is saturated.

The solid electrolyte layer 18 contains lithium ions and is made of a material through which lithium ions can move. For the solid electrolyte layer 18, it is preferable to use _, for example, LiPON in which N is doped in lithium phosphate ( _Li3PO4 ).

The negative electrode layer 20 is made of a material capable of intercalating and deintercalating lithium ions, such as niobium oxide (Nb ₂ O ₅ ), vanadium oxide (V ₂ O ₅ ), indium oxide (In ₂ O ₃ ), lithium-titanium oxide. (Li ₄ Ti ₅ O ₁₂ ), indium tin oxide (ITO) and other metal oxide thin films.

In addition to the above, metal lithium (Li), metal tin (Sn), or the like can also be used. When metallic lithium (Li), metallic tin (Sn), or indium tin oxide (ITO) is used as the negative electrode layer 20 , the negative electrode layer 20 can also serve as the negative electrode current collector layer 22 .

More preferably, the negative electrode layer 20 is further doped with N. The doping amount of N in the negative electrode layer 20 is preferably 0.1 at % to 10.0 at %, more preferably 1.0 at % to 5.0 at %. By setting the doping amount of N to 0.1 at % or more, the effect of improving the ionic conductivity can be obtained more reliably. When the doping amount of N exceeds 10.0 atomic %, the effect of improving the ionic conductivity is saturated.

The thin film lithium secondary battery 10 can be produced by a sputtering method, a vapor deposition method, a coating method, or the like. In the coating method, a desired oxide layer is obtained by coating the substrate 12 with an organometallic compound together with an organic solvent and heating and decomposing it. In the case of the present embodiment, the sputtering method is preferable because it can form a uniform film over a relatively large area with little deviation in composition.

The thickness of each layer is preferably several tens of nm to several μm. The thicknesses of the positive electrode layer 16 and the negative electrode layer 20 are preferably such that the overall capacity of each layer obtained by multiplying the capacity per unit volume of each layer by the film thickness and the area is the same. The thickness of the positive electrode layer 16 is more preferably 100 nm to 1000 nm. The thickness of the positive electrode layer 16 is preferably 50% to 1000% of the thickness of the solid electrolyte layer 18 . The thickness of the solid electrolyte layer 18 is preferably 10 nm to 1000 nm, and in order to reduce the resistance and increase the conductivity, it is more preferable to make it as thin as possible without causing short circuits due to defects such as pinholes. .

The thickness of the negative electrode layer 20 is preferably such that the overall layer capacity matches the overall layer capacity of the positive electrode layer 16 . For example, when the capacity per unit volume of the negative electrode layer 20 is greater than the capacity per unit volume of the positive electrode layer 16 , the thickness of the negative electrode layer 20 is preferably thinner than the thickness of the positive electrode layer 16 . Specifically, when the capacity per unit volume of the negative electrode layer 20 is twice the capacity per unit volume of the positive electrode layer 16 and the thickness of the positive electrode layer 16 is 100 nm to 1000 nm, the thickness of the negative electrode layer 20 is is preferably between 50 nm and 500 nm, which is half the thickness of the positive electrode layer 16 . The thickness of the negative electrode layer 20 is preferably 50% to 1000% of the thickness of the solid electrolyte layer 18 .

When the thin-film lithium secondary battery 10 is charged, the positive electrode current collector layer 14 and the negative electrode current collector layer 22 are connected to a power supply (not shown), and a voltage is applied between the positive electrode current collector layer 14 and the negative electrode current collector layer 22 . applied. Then, lithium in the positive electrode layer 16 is desorbed from the positive electrode layer 16 to become lithium ions, which migrate to the negative electrode layer 20 through the solid electrolyte layer 18 . As the above reaction continues, the amount of lithium in the positive electrode layer 16 decreases, and lithium ions combine with electrons in the negative electrode layer 20 and accumulate in the negative electrode layer 20 .

When the thin-film lithium secondary battery 10 is discharged, the positive electrode current collector layer 14 and the negative electrode current collector layer 22 are connected to an external circuit (not shown), and a potential difference is generated between the positive electrode current collector layer 14 and the negative electrode current collector layer 22. occurs. Then, lithium in the negative electrode layer 20 becomes lithium ions and moves to the positive electrode layer 16 through the solid electrolyte layer 18, and electrons move from the negative electrode layer 20 to the positive electrode layer 16 through the external circuit. In the positive electrode layer 16 , lithium ions and electrons are combined and accumulated in the positive electrode layer 16 . The above reaction causes current to flow in the external circuit.

The cathode layer, which is inherently undoped with N, is an aggregate of crystallites. It is believed that the doping of N makes the positive electrode layer 16 amorphous and improves the ionic conductivity. Since the thin-film lithium secondary battery 10 according to the present embodiment includes the N-doped positive electrode layer 16, the ionic conductivity of the positive electrode layer 16 is improved. An increase in resistance is suppressed. Therefore, since lithium ions can smoothly move in the thickness direction in the positive electrode layer 16, the thin film lithium secondary battery 10 can effectively utilize the positive electrode layer 16, and as a result, the charge/discharge capacity can be increased. can be done. In addition, since the thin-film lithium secondary battery 10 has a low internal resistance, even if it is charged and discharged with a large current, the charge-discharge capacity does not decrease, and it can be charged and discharged quickly, and can achieve higher output than conventional batteries.

In the thin-film lithium secondary battery 10, by doping the negative electrode layer 20 with N as well, the ion conductivity of the negative electrode layer 20 is improved and the charge/discharge capacity can be increased. Thus, both the positive electrode layer 16 and the negative electrode layer 20 may be doped with N.

Also, in the thin film lithium secondary battery 10 , N may be doped only in the negative electrode layer 20 instead of the positive electrode layer 16 . Since the thin-film lithium secondary battery 10 includes the negative electrode layer 20 doped with N, the ion conductivity of the negative electrode layer 20 is improved, and even if the thickness of the negative electrode layer 20 is increased, the increase in internal resistance is suppressed. be done. Therefore, since lithium ions can smoothly move in the thickness direction of the negative electrode layer 20, the thin film lithium secondary battery 10 can effectively utilize the negative electrode layer 20, and as a result, the charge/discharge capacity can be increased. can be done. The doping amount of N is preferably 0.1 at % to 10.0 at %, more preferably 1.0 at % to 5.0 at %, as in the above embodiment.

As described above, in the thin-film lithium secondary battery 10 , at least one of the positive electrode layer 16 and the negative electrode layer 20 contains N, thereby improving the ionic conductivity of the positive electrode layer 16 and/or the negative electrode layer 20 . Therefore, the thin film lithium secondary battery 10 can increase the charge/discharge capacity by increasing the film thickness of the positive electrode layer 16 and/or the negative electrode layer 20, and even if the charge/discharge is performed with a large current, the charge/discharge capacity is increased. Decrease in capacity can be reduced.

(Example 1)
A thin-film lithium secondary battery was actually produced and its effect was verified. A glass substrate was used as a substrate, and a thin film lithium secondary battery was fabricated on the glass substrate by a sputtering method (magnetron sputtering device, CS-200, manufactured by ULVAC, Inc.) according to the following procedure.

First, on a glass substrate (non-alkali glass, 50 mm×50 mm, thickness 1 mm), a Ti metal target was used to form a Ti film having a thickness of 100 nm as a positive electrode current collector layer. Detailed sputtering conditions are as shown in Table 1. The substrate temperature during film formation was room temperature.

On the Ti film (positive electrode current collector layer), Li ₂ Mn ₂ O ₄ oxide sintered body was used as a target, and a sputtering gas containing N was used to deposit Li ₂ Mn ₂ O ₄ with a predetermined thickness as a positive electrode layer. A film was formed. Three thicknesses of 200 nm, 400 nm, and 600 nm were used for the positive electrode layer.

A LiPON film having a thickness of 100 nm was formed as a solid electrolyte layer on the Li ₂ Mn ₂ O ₄ film (positive electrode layer) by introducing a sputtering gas containing N using a Li ₃ PO ₄ oxide sintered body target. . An Nb ₂ O ₅ film having a predetermined thickness was formed as a negative electrode layer on a LiPON film (solid electrolyte layer) using a target of Nb ₂ O ₅ oxide sintered body. The thickness of the negative electrode layer was 100 nm for the 200 nm thick positive electrode layer, 200 nm for the 400 nm thick positive electrode layer, and 300 nm for the 600 nm thick positive electrode layer.

On the Nb ₂ O ₅ film (negative electrode layer), similarly to the positive electrode current collector layer, a Ti film having a thickness of 100 nm was formed as the negative electrode current collector layer. Samples No. 1 to No. 6 according to Examples were produced as described above. Sample No. ₂ according to the example provided with a positive electrode layer and a negative electrode layer containing N by the same method as described above except that a sputtering gas containing N is used when forming the Nb 2 O ₅ film (negative electrode layer). .7 to No.12 were produced.

For comparison, comparative examples were prepared by the same method as in Samples No. 1 to No. 6, except that a sputtering gas containing no N was used when forming the Li ₂ Mn ₂ O ₄ film (positive electrode layer). Such samples No. 1 to No. 6 were produced.

The doping amount of N in the positive electrode layer and the negative electrode layer was determined by using an electron probe micro analyzer (EPMA; Electron Probe Micro Analyzer, manufactured by JEOL Ltd., JEOL JXA -8530F) was used to analyze and measure. In the above samples, only a positive electrode layer or a negative electrode layer was formed on a glass substrate under the same conditions as the samples of each example (conditions with N in Table 1). The results are shown in the column of "nitrogen atom ratio" in Table 2.

The charge/discharge characteristics of the produced thin film secondary battery were evaluated. In the evaluation, it was sealed with a barrier film made of Al and resin in order to avoid the influence of moisture in the air. The charge/discharge characteristics were measured at a temperature of 25° C. using a charge/discharge measuring device (manufactured by Asuka Denshi Co., Ltd.). The measured current was as shown in Table 2, and the voltage range was 3.5-0.3V. Table 2 shows the results.

(Example 2)
Samples No. 13 to No. 18 according to Example 2 were produced in the same manner as in Example 1 above, except that the positive electrode layer was a LiMnCoO ₄ film. In the formation of this positive electrode layer, a LiMnCoO ₄ oxide sintered body target was used, and a sputtering gas containing N was introduced to form LiMnCoO ₄ films with three different thicknesses of 200 nm, 400 nm, and 600 nm. Samples No. 7 to No. 12 according to Comparative Example 2 were prepared in the same manner as in Samples No. 13 to No. 18 except that a sputtering gas containing no N was used when forming the LiMnCoO ₄ film. made. The doping amount of N and the charge/discharge characteristics of these samples were measured in the same manner as in Example 1 and Comparative Example 1 above. The results are shown in Table 3 together with the film configuration and the measured current.

(Example 3)
Samples No. 19 to No. 24 according to Example 3 were produced in the same manner as in Example 1 above, except that the positive electrode layer was a LiCoO ₂ film. In the formation of this positive electrode layer, a LiCoO ₂ oxide sintered body target was used, and a sputtering gas containing N was introduced to form LiCoO ₂ films with three different thicknesses of 200 nm, 400 nm, and 600 nm. Samples No. 13 to No. 18 according to Comparative Example 3 were obtained in the same manner as in Samples No. 19 to No. 24 except that a sputtering gas containing no N was used when forming the LiCoO ₂ film. made. The doping amount of N and the charge/discharge characteristics of these samples were measured in the same manner as in Example 1 and Comparative Example 1 above. The results are shown in Table 4 together with the film configuration and the measured current.

(Example 4)
Samples No. 25 to No. 30 according to Example 4 were produced in the same manner as in Example 1 above, except that the negative electrode layer was a Li ₄ Ti ₅ O ₁₂ film. In the formation of this negative electrode layer, a Li ₄ Ti ₅ O ₁₂ oxide sintered body target was used, a sputtering gas containing N was introduced, and Li ₄ Ti ₅ O ₁₂ having three thicknesses of 200 nm, 400 nm, and 600 nm was formed. A film was formed. Samples No. 19 to No. 19 according to Comparative Example 3 were formed in the same manner as in Samples No. 25 to No. 30 except that a sputtering gas containing no N was used when forming the Li ₄ Ti ₅ O ₁₂ film. No.24 was produced. The doping amount of N and the charge/discharge characteristics of these samples were measured in the same manner as in Example 1 and Comparative Example 1 above. The results are shown in Table 5 together with the film configuration and the measured current.

Samples No. 1 to No. 6 and No. 13 to No. 24 according to Examples are examples containing N in the positive electrode layer, and Samples No. 25 to No. 30 are examples containing N in the negative electrode layer, Samples No. 7 to No. 12 are examples in which N is contained in both the positive electrode layer and the negative electrode layer. The charge/discharge capacities in Tables 2 to 5 show values at the 100th cycle when the charge/discharge capacities stabilize. As shown in Tables 2 to 5, it was confirmed that Samples No. 1 to No. 30 according to the examples showed an increase in charge/discharge capacity as the film thicknesses of the positive and negative electrodes increased. For example, in Example 1, sample No. 1 and sample No. 3 having different film thicknesses are compared. Sample No. 1 has a positive electrode layer thickness of 200 (nm), a charge capacity of 64 (μAh), and a discharge capacity of 62 (μAh). On the other hand, sample No. 3 has a positive electrode layer thickness of 600 (nm), a charge capacity of 151 (μAh), and a discharge capacity of 148 (μAh). Therefore, sample No. 3 has a positive electrode layer thickness three times that of sample No. 1, and a charge/discharge capacity approximately 2.4 times larger.

In addition, it was confirmed that samples No. 1 to No. 30 according to the examples showed little decrease in charge/discharge capacity even when the measured current was increased. For example, in Example 1, sample No. 1 and sample No. 4, which have the same film structure and differ only in the measurement current, are compared. Sample No.1 has a charge capacity of 64 (μAh) and a discharge capacity of 62 (μAh) when the measured current is 20 (μA), while sample No.4 has a measured current of 100 (μA). , the charge capacity is 58 (μAh) and the discharge capacity is 56 (μAh). Therefore, Sample No. 4 shows less decrease in charge/discharge capacity than Sample No. 1 even if the measured current is increased five times.

Samples No. 1 to No. 24 according to the comparative examples did not increase the charge/discharge capacity much compared to the examples with respect to the increase in the film thickness of the positive electrode and the negative electrode, and samples No. 1 to No. according to the examples. It was confirmed that the charge/discharge capacity was smaller than that of .30. For example, in Comparative Example 1, sample No. 1 and sample No. 3 having different film thicknesses are compared. Sample No. 1 has a positive electrode layer thickness of 200 (nm), a charge capacity of 50 (μAh), and a discharge capacity of 47 (μAh). On the other hand, sample No. 3 has a positive electrode layer thickness of 600 (nm), a charge capacity of 86 (μAh), and a discharge capacity of 82 (μAh). Therefore, in sample No. 3, although the thickness of the positive electrode layer is three times that of sample No. 1, the charge/discharge capacity remains less than twice that of sample No. 1, and the charge/discharge capacity is smaller than that of Example 1.

It was also confirmed that the charge/discharge capacities of samples No. 1 to No. 24 according to the comparative examples significantly decreased as compared with the examples when the measured current was increased. For example, in Comparative Example 1, sample No. 1 and sample No. 4, which have the same film configuration and differ only in the measurement current, are compared. Sample No.1 has a charge capacity of 50 (μAh) and a discharge capacity of 47 (μAh) when the measured current is 20 (μA), while sample No.4 has a measured current of 100 (μA). , the charge capacity is 26 (μAh) and the discharge capacity is 23 (μAh). Therefore, the charge/discharge capacity of Sample No. 4 was reduced to about half of that of Sample No. 1 by increasing the measured current by five times, and the charge/discharge capacity of Sample No. 1 was greatly reduced compared to Example 1.

From the above results, it can be said that the examples have higher charge/discharge capacities than the comparative examples at least when the film thickness of the positive electrode layer is 200 nm or more. In addition, in the example, as the thickness of the positive electrode layer increases from 200 nm, the charge/discharge capacity increases almost proportionally, and the difference from the comparative example, in which the increase is small, becomes larger.

Samples No. 1 to No. 30 according to the examples were all confirmed to have stable cycle characteristics of 1000 cycles or more with respect to charge/discharge curves and charge/discharge capacities. As an example, the voltage-charge/discharge capacity characteristics and charge/discharge capacity cycle characteristics of Sample No. 1 of Example 1 are shown in FIGS.

(Modification)
The present invention is not limited to the above embodiments, and can be appropriately modified within the scope of the present invention. In the above embodiment, the case of forming the positive electrode layer and the negative electrode layer containing N by a sputtering method using a sputtering gas containing N has been described, but the present invention is not limited to this. For example, a positive electrode layer and a negative electrode layer that do not contain N may be doped with N by ion implantation.

In the case of the above embodiment, the case where each of the positive electrode current collector layer 14, the positive electrode layer 16, the solid electrolyte layer 18, the negative electrode layer 20, and the negative electrode current collector layer 22 is provided has been described. The present invention is not limited to this. For example, a configuration in which a positive electrode layer and a negative electrode layer are respectively arranged on both sides of a solid electrolyte layer is used as a basic configuration, and multiple layers of this basic configuration may be laminated with a current collector layer interposed therebetween.

A barrier film such as silicon nitride or silicon oxide may be formed on the surface of the thin film lithium secondary battery 10, the entire thin film lithium secondary battery 10 may be sealed with an Al or resin film, or molded with resin. In addition, a treatment may be applied to prevent deterioration due to moisture in the air and contamination.

10 thin film lithium secondary battery 12 substrate 14 positive electrode current collector layer 16 positive electrode layer 18 solid electrolyte layer 20 negative electrode layer 22 negative electrode current collector layer

Claims (2)

A positive electrode layer, a solid electrolyte layer, and a negative electrode layer,
The positive electrode layer is a sputtered film of metal oxide containing lithium, doped with nitrogen (N) throughout the film.
Thin-film lithium secondary battery. The positive electrode layer contains lithium-manganese oxide, lithium-cobalt oxide, or lithium-manganese-cobalt oxide, the negative electrode layer contains niobium oxide or lithium-titanium oxide, and the solid electrolyte layer contains lithium phosphate. 2. The thin-film lithium secondary battery according to claim 1, comprising LiPON to which nitrogen (N) is added.

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