What Are Lithium Batteries?

Lithium batteries are electrochemical cells that use lithium as an active electrode material, either as lithium metal or as a lithium-intercalation compound. The category spans primary (non-rechargeable) cells, which deliver high energy density in a single discharge cycle, and secondary (rechargeable) cells, which include lithium-ion, lithium-polymer, lithium-iron phosphate, and lithium-sulfur chemistries. Lithium batteries have displaced most competing chemistries in portable electronics and now dominate electric vehicle propulsion and stationary grid storage.

The category's commercial history begins with non-rechargeable lithium metal cells introduced in the 1970s, which found use in cameras, medical implants, and military equipment. Rechargeable lithium-ion cells, commercialized by Sony in 1991 based on earlier work by John Goodenough, Rachid Yazami, and Akira Yoshino, transformed the field by enabling safe, repeated cycling without lithium plating. The IEEE Guide for Characterization and Evaluation of Lithium-Based Batteries in Stationary Applications (IEEE 1679.1-2025) provides the current standardized framework for comparing lithium battery technologies in grid-scale deployments.

Cell Chemistry and Electrode Materials

The energy a lithium battery can store and deliver depends on the choice of cathode and anode materials. Common cathode formulations include lithium cobalt oxide (LCO), used in consumer electronics for its high volumetric energy density; lithium iron phosphate (LFP), preferred in stationary and vehicle applications for its thermal stability and cycle life; and nickel manganese cobalt oxide (NMC), which balances energy density and longevity in electric vehicle packs. The anode is most commonly graphite, though silicon-blended anodes are appearing in commercial cells as a route to higher capacity.

Cell voltage depends on the difference in electrochemical potential between cathode and anode materials, typically ranging from 2.5 to 4.2 volts per cell, and energy density for commercial lithium-ion cells reaches 150 to 300 Wh/kg at the cell level.

Safety and Thermal Management

Lithium batteries can undergo thermal runaway, an exothermic chain reaction triggered by mechanical damage, overcharging, or internal short circuits that produces heat and, in severe cases, fire. Battery management systems (BMS) monitor cell voltage, current, and temperature to keep each cell within its safe operating window. Thermal management subsystems, using liquid cooling plates, heat pipes, or phase-change materials, maintain cell temperatures in the 15 to 40 degree Celsius range that maximizes both safety and calendar life.

The DOE Energy Storage Handbook chapter on lithium-ion batteries, produced by Sandia National Laboratories, reviews failure modes, testing standards, and installation safety requirements for utility-scale lithium battery systems.

Charging and Cycle Life

Lithium batteries are charged using constant-current/constant-voltage (CC/CV) protocols. The constant-current phase fills most of the cell's capacity; the constant-voltage phase, held at the upper cutoff voltage, completes charging while limiting lithium plating. Cycle life, the number of complete charge-discharge cycles before capacity falls below 80% of initial value, ranges from around 500 cycles for LCO cells to 2,000 cycles or more for LFP. Fast charging, at rates above 1C (full charge in under one hour), accelerates degradation through lithium plating and electrolyte decomposition, and is an active research focus at institutions such as Argonne National Laboratory.

Applications

Lithium batteries have applications across a wide range of sectors, including:

• Electric vehicle propulsion and regenerative braking storage
• Portable consumer electronics (smartphones, laptops, wearables)
• Grid-scale frequency regulation and peak-shaving storage systems
• Medical implants (pacemakers, defibrillators) using primary lithium cells
• Aerospace and defense systems requiring high energy-to-weight ratios