FIELD

Embodiments of the present invention described herein relate generally to a nonaqueous electrolyte battery and a battery pack.

BACKGROUND

Among nonaqueous electrolyte batteries, extensive studies have been made as a high-energy density battery, for those performing charge and discharge by movement of lithium ions between the negative and positive electrodes.

Nonaqueous electrolyte batteries are anticipated to be used as a medium-sized or large-sized power supply for onboard and stationary applications and the like, in addition to the use as a power supply for compact electronic devices. Excellent life performance and high security are desired in the application field of medium-sized and large-sized power supplies. In addition, high input/output performance may be demanded in some cases.

A nonaqueous electrolyte battery using spinel lithium titanate for the negative electrode is known as a nonaqueous electrolyte battery having excellent life performance and high safety. However, since the lithium insertion/extraction potential of spinel lithium titanate is as high as about 1.55 V (vs. Li/Li+), the nonaqueous electrolyte battery using the spinet lithium titanate for the negative electrode active material cannot obtain a high battery voltage. In addition, since spinel lithium titanate exhibits a flat charge/discharge curve in the lithium insertion/extraction potential range, a change in potential upon a change in charge state is small.

On the other hand, among oxides of titanium, a lithium-sodium-titanium composite oxide such as Li2Na2Ti6O14can perform lithium insertion and extraction at a low potential, and the operating potential of this composite oxide is about 1.25 V (vs. Li/Li+). However, assignments exist regarding the input/output performance at a low temperature for the nonaqueous electrolyte battery containing Li2Na2Ti6O14for the negative electrode active material.

CITATION LIST

Patent Literatures

Patent Literature 1: Japanese Patent No. 4237659Patent Literature 2: WO2016/088193A1

SUMMARY

Technical Problem

It is an object of the embodiments to provide a nonaqueous electrolyte battery excellent in input/output performance even at a low temperature and a battery pack including the nonaqueous electrolyte battery.

Solution to Problem

According to one embodiment, provided is a nonaqueous electrolyte battery including a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode contains a negative electrode active material containing orthorhombic Na-containing niobium-titanium composite oxide particles represented by general formula (1) Li2+vNa2−yM1xTi6−y−zNbyM2zO14+δ. In general formula (1), M1 is one or two or more elements selected from the group consisting of Cs, K, Sr, Ba, and Ca, M2 is one or two or more elements selected from the group consisting of Zr, Al, Sn, V, Ta, Mo, W, Fe, Co, and Mn, 0≤v<2, 0≤x<2, 0<y<2, 0≤z<3, and −0.5≤δ≤0.5. The nonaqueous electrolyte contains an Na component in a range of 10 ppm by mass to 3,000 ppm by mass.

In addition, according to one embodiment, provided is a battery pack. The battery pack includes the nonaqueous electrolyte battery according to the embodiment.

