What are the differences between low-voltage and high-voltage
lithium polymer batteries?
1. Main Difference: Voltage Platform and Energy Density
Low-voltage version: Typically refers to ternary lithium batteries
with a 3.6V/3.7V voltage platform. Its full-charge cutoff voltage
is generally 4.2V, and its discharge cutoff voltage is
approximately 2.75V-3.0V.
High-voltage version: Typically refers to ternary lithium batteries
with a 3.8V/3.85V voltage platform. Its full-charge cutoff voltage
is higher, generally 4.35V or 4.4V, and its discharge cutoff
voltage is also approximately 2.75V-3.0V.
Key Impact: At the same capacity (1000mAh), the high-voltage
version, due to its higher voltage platform, delivers more actual
electrical energy (Wh) according to the formula "Energy = Voltage ×
Capacity," providing a longer single-charge usage time for devices.
2. Applicable Devices and Charging Requirements
Low-voltage version (4.2V cutoff): Suitable for devices with
traditional designs whose charging management ICs (chips) only
support a 4.2V full-charge cutoff voltage. Using a low-voltage
battery in a high-voltage charging circuit may result in
insufficient charging and incomplete capacity utilization.
High-voltage version (4.35V/4.4V cutoff): Requires the device's
charging management IC to support a higher cutoff voltage. Using a
high-voltage battery in a device that only supports 4.2V charging
will prevent the battery from being fully charged, significantly
reducing its usable capacity. Conversely, using a high-voltage
charger to charge a low-voltage battery can lead to overcharging,
posing a safety risk.
3. Materials and Cycle Life
Differences in voltage platforms stem from adjustments to the
cathode material formulation, thus affecting cycle life.
Low-voltage version: The cathode material formulation is more
mature, resulting in relatively better cycle stability. Under
standard charge and discharge conditions, the cycle life typically
reaches 500-800 cycles (capacity retention ≥80%).
High-voltage version: To improve the voltage platform, the cathode
material undergoes special modifications, but the material
structure is more prone to aging under high-voltage conditions.
Therefore, its cycle life is usually slightly lower than that of
the low-voltage version, generally between 400-600 cycles (capacity
retention ≥80%).
Main Features:
Performance Characteristics
Stable Voltage and Capacity: With a nominal voltage of 3.7V, it
provides a stable power output to devices, ensuring normal
operation. The nominal capacity of 1000mAh meets the power needs of
some small to medium power devices.
High Energy Density: Despite its small size, this battery provides
3.7Wh of energy, making it suitable for devices with limited space.
Good Charge/Discharge Performance: The standard charging current is
typically 0.2C (200mA), and the fast charging current can reach
0.5C (500mA), allowing for a quick full charge.
The discharge cutoff voltage is 2.75V, allowing for normal
discharge within a temperature range of -20℃ to 60℃.
Long Cycle Life: Under 0.2C charge/discharge conditions, after 500
cycles at room temperature, the battery capacity retains over 80%,
demonstrating a long service life and reducing operating costs.
Low self-discharge rate: The self-discharge rate of lithium
batteries differs between a fully charged state and a 70% charge
state. The self-discharge rate is slightly higher at a full charge
than at 70%, but the overall self-discharge rate is low, allowing
for long-term storage.
Protection Functions:
Overcharge Protection: When the battery charging voltage reaches or
exceeds the set overcharge detection voltage (e.g., 4.28V±50mV),
the internal protection circuit automatically cuts off the charging
circuit to prevent damage from overcharging and potential safety
hazards.
Over-discharge Protection: When the battery discharge voltage is
lower than the set over-discharge detection voltage (e.g.,
2.4V±100mV), the protection circuit cuts off the discharge circuit
to prevent over-discharge and extend battery life.
Overcurrent Protection: When the battery discharge current exceeds
its rated maximum discharge current, the protection circuit quickly
activates, cutting off the discharge circuit to prevent overheating
and damage to the battery due to overcurrent.
Short Circuit Protection: If an accidental short circuit occurs
between the positive and negative terminals of the battery, the
protection circuit will respond immediately, cutting off the
circuit to avoid battery damage and safety hazards caused by the
short circuit.
Over-temperature protection: When the internal temperature of the
battery becomes too high due to various reasons (such as high
current charging and discharging, or excessively high ambient
temperature), the protection circuit will activate the
over-temperature protection function to stop the charging and
discharging operation of the battery and ensure battery safety.
