What is equivalent to a Pouch cell (no size designation)?

Li-poly, Li-Po, lithium polymer, pouch cell, LiPo — all the same 3.7 V cell under different manufacturer codes.

Can I use a Any cylindrical Li-ion instead of a Pouch cell (no size designation)?

A pouch cell has no standard size at all — the dimension code on the label, such as 603048, is simply thickness, width and length in tenths of a millimetre and millimetres. Two cells with different codes are different cells, and a pouch has no metal can to contain a failure.

Is the Pouch cell (no size designation) rechargeable?

Yes. Use a charger made for its chemistry and never substitute a primary cell of the same size.

Pouch cell (no size designation) battery

What replaces a Pouch cell (no size designation)

Li-poly, Li-Po, lithium polymer, pouch cell, LiPo

3.7 V lithium-ion (rechargeable)

The Pouch cell (no size designation) is a rechargeable 3.7 V lithium-ion (rechargeable) pack. The codes below are the same physical cell sold under different manufacturer names, and any of them will fit.

Specification

IEC designation: Pouch cell (no size designation)
Nominal voltage: 3.7 V
Chemistry: Lithium-ion (rechargeable)
Rechargeable: Yes

Codes that mean the same battery

Different manufacturers, one physical battery. Voltage, chemistry and dimensions all match.
Code	Fits?
Li-poly	Yes — same cell
Li-Po	Yes — same cell
lithium polymer	Yes — same cell
pouch cell	Yes — same cell
LiPo	Yes — same cell

Codes that look close but are not

Code	Why it is not a substitute
Any cylindrical Li-ion	A pouch cell has no standard size at all — the dimension code on the label, such as 603048, is simply thickness, width and length in tenths of a millimetre and millimetres. Two cells with different codes are different cells, and a pouch has no metal can to contain a failure.
NiMH packs	Same connector styles are sold for both. A NiMH charger applied to a LiPo will overcharge it, and an overcharged LiPo swells and can ignite.

Where it turns up

Phones, tablets and laptops
Bluetooth earbuds and their cases
Drones and RC models
Smartwatches and fitness bands

The chemistry is lithium-ion; "polymer" describes the gelled electrolyte and the soft foil pouch, not a different cell reaction. 3.7 V nominal, 4.2 V charged, and a hard floor around 3.0 V. A swollen pouch is a failed cell — stop charging it, do not puncture it, and dispose of it at a battery collection point rather than in household waste.

Common questions

What is equivalent to a Pouch cell (no size designation)?: Li-poly, Li-Po, lithium polymer, pouch cell, LiPo — all the same 3.7 V cell under different manufacturer codes.
Can I use a Any cylindrical Li-ion instead of a Pouch cell (no size designation)?: A pouch cell has no standard size at all — the dimension code on the label, such as 603048, is simply thickness, width and length in tenths of a millimetre and millimetres. Two cells with different codes are different cells, and a pouch has no metal can to contain a failure.
Is the Pouch cell (no size designation) rechargeable?: Yes. Use a charger made for its chemistry and never substitute a primary cell of the same size.

CRV3 battery 3 V lithium (primary)
CR2032 battery 3 V lithium (primary)
LR6 battery 1.5 V alkaline
LR03 battery 1.5 V alkaline
6LR61 battery 9 V alkaline
LR44 battery 1.5 V alkaline
CR2025 battery 3 V lithium (primary)
ICR18650 battery 3.6 V lithium-ion (rechargeable)
SR626SW battery 1.55 V silver oxide
LR20 battery 1.5 V alkaline
HR6 battery 1.2 V nickel-metal hydride
LR14 battery 1.5 V alkaline

Sources

Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked