What are the respective characteristics of maintenance-free batteries and lithium batteries? With the vigorous development of the new energy industry, various related sectors are emerging constantly. Driven by the boom of new energy, storage battery technology keeps upgrading and new types of lithium batteries are launched continuously. As a result, lithium batteries or new-type batteries have been widely adopted in an increasing number of devices. Let’s take a look at the respective features of maintenance-free batteries and lithium batteries below.

What are the respective characteristics of maintenance-free batteries and lithium batteries?

A maintenance-free battery refers to a storage battery that requires no maintenance such as electrolyte replenishment within its valid service life. During charging, electric energy is converted into chemical energy; during discharging, chemical energy is converted back into electric energy. When discharging, metallic lead serves as the negative electrode and undergoes oxidation reaction to form lead sulfate; lead dioxide acts as the positive electrode and undergoes reduction reaction and is reduced to lead sulfate.

A lithium battery is a type of battery adopting lithium metal or lithium alloy as the negative electrode material and non-aqueous electrolyte solution. It mainly operates relying on the migration of lithium ions between the positive and negative electrodes. During charging and discharging, Li+ intercalates and deintercalates back and forth between the two electrodes: during charging, Li+ deintercalates from the positive electrode, passes through the electrolyte and intercalates into the negative electrode, making the negative electrode lithium-rich; the process reverses during discharging.

Characteristics of Maintenance-free Batteries

1. Benefiting from structural advantages, maintenance-free batteries consume very little electrolyte and basically require no distilled water replenishment throughout their service life. They also feature shock resistance, high temperature resistance, compact size and low self-discharge rate, with a service life generally twice that of ordinary batteries.

2. Adopting lead-calcium alloy grids, maintenance-free batteries produce less water decomposition and water evaporation during charging. Equipped with a sealed housing, they release little sulfuric acid gas. Compared with other batteries, they require no liquid topping-up, cause less corrosion to terminals and wires, feature strong overcharge resistance, large starting current and long electric energy storage duration.

3. Under normal charging voltage, only a small amount of gas is generated from the electrolyte of maintenance-free batteries, so no distilled water addition is needed during the whole service period. No removal for supplementary charging is required if the charging system works properly. Nevertheless, the specific gravity of electrolyte shall be inspected during routine maintenance.

4. No acid mist escapes during normal charging and discharging of maintenance-free batteries. Hydrogen and oxygen generated from water decomposition are converted back into water inside the battery via catalyst and pressure regulation. Gas is only discharged externally when internal pressure exceeds the preset value of pressure relief valve under overcharge conditions, leading to low electrolyte consumption under normal use.

5. Equipped with an innovative safety synchronization device, maintenance-free batteries can confine acid gas inside individual cells and prevent sparks from entering the battery interior. This not only reduces the risk of battery explosion caused by external factors, but also keeps the battery top cover dry to mitigate terminal corrosion and ensure firm and reliable electrical circuit connection.

Characteristics of Lithium Batteries

1. Both lithium batteries and lead-acid batteries lose usable capacity in low-temperature environments, yet the capacity attenuation is far more severe for lead-acid batteries. At -20°C, the available capacity of lead-acid batteries drops to 30%, while lithium batteries retain 82% of their capacity under identical discharge conditions. Lithium batteries deliver longer service life not only in high-temperature regions but also in frigid mountainous areas.

2. Low self-discharge rate and no memory effect. A built-in protection board for lithium batteries provides overcharge and over-discharge protection. Lithium batteries can withstand high-rate power output; lithium batteries used for electric vehicles support high-efficiency charge and discharge at 15–30C to meet the demand for intense starting and acceleration of vehicles.

3. Excellent high-rate discharge capability. Lithium iron phosphate lithium batteries for electric vehicles support 15–30C charge and discharge to satisfy high-intensity starting and acceleration. Almost no water is consumed during lithium battery production, which is highly favorable for water-scarce regions in China.

4. High single-cell voltage and light weight. The average voltage of a single cell reaches 3.7V or 3.2V, equivalent to the series voltage of 2 to 4 nickel-metal hydride or nickel-cadmium cells. It is easy and convenient to assemble lithium battery packs to boost overall voltage to meet customers’ high-voltage requirements.

Lithium batteries and maintenance-free batteries differ greatly in safety performance: maintenance-free batteries have slightly better safety performance. Maintenance-free batteries are relatively low-cost, while lithium batteries come with a higher price tag.

Lithium batteries are manufactured based on lithium materials with lithium metal or lithium alloy as negative electrode and non-aqueous electrolyte solution. By contrast, maintenance-free batteries are lead-based storage batteries whose electrodes are mainly composed of lead and its oxides, with sulfuric acid solution as electrolyte. Waste generated during the production of lead-based maintenance-free batteries will cause environmental pollution, while lithium batteries have no such drawback.