Semco university – All about the Lithium-Ion Batteries


How Internal Resistance Shapes Lithium Battery Performance

Lithium batteries are used extensively in mobile communications, energy storage systems, electric vehicles, and other industries as an effective and sustainable energy storage technology. Internal resistance is a crucial metric in the assessment of lithium battery performance.

This essay will provide an overview of internal resistance and provide a detailed analysis of its definition, measurement techniques, contributing variables, and mitigation strategies.

Definition and function of internal resistance

(1) Internal resistance definition

The resistance that the lithium battery’s internal current encounters when it is being charged or discharged is referred to as internal resistance. It is influenced by several elements, including the electrolyte’s ion transmission rate, the conductivity of the material inside the battery, and the contact resistance between the electrolyte and electrode. Lithium battery performance, including output power, cycle life, temperature characteristics, etc., is directly impacted by internal resistance.

(2) Internal resistance’s function in lithium batteries

One of the things that restricts the output power of lithium batteries is internal resistance. When a battery has a high internal resistance, there will be a significant voltage drop as current flows through the battery’s interior, which lowers the battery’s output power.

2. The battery will self-discharge due to internal resistance. The battery will also have some current flowing through it when it is not operating because of the resistance inside the battery; this leads to the battery’s self-discharge phenomenon.

3. The battery’s temperature characteristics are impacted by the internal resistance. Batteries with higher internal resistance will produce more heat during charging or discharging, raising the battery’s temperature and impairing its overall performance.

DC internal resistance is used to assess the battery’s qualities. DC internal resistance is frequently used in practical applications to assess the condition of lithium batteries, forecast their lifespan, and calculate the system’s SOC (state of charge) and SOP (state of power). The battery’s DC internal resistance can be measured to provide information about its condition. T

his information can then be used to manage and control the battery and extend its lifespan and efficiency in the following ways:

1. Health Evaluation:

The rate of capacity attenuation and the rate at which internal resistance increases are typically used to assess the degree of degradation of lithium batteries during use. The battery’s health can be assessed by looking at the change in DC internal resistance, which can represent both chemical and physical changes inside the battery. A battery’s internal resistance usually rises as its condition declines.

2. Life Expectancy:

One significant sign that a battery is getting older is an increase in internal resistance. Battery life can be estimated by tracking changes in the battery’s DC internal resistance. A battery that needs to be replaced or repaired is one that is nearing or has surpassed its design life when the DC internal resistance reaches a particular threshold.

3. System SOC Estimation:

The ratio of the battery’s remaining usable energy to its total energy is known as the state of charge, or SOC, of a given battery. The DC internal resistance of the battery and its state of charge (SOC) have a specific relationship, and the DC internal resistance of the battery can be used to estimate the SOC. By measuring the battery’s DC internal resistance, one can estimate the state of charge (SOC) in accordance with the current internal resistance-charge state relationship model.

4. System SOP Estimation:

The state of power that a battery is currently in, or the maximum power it can produce, is referred to as its SOP. Additionally, there is a relationship between the battery’s SOP and DC internal resistance; the SOP of the battery can be estimated by measuring the DC internal resistance.


Internal resistance, though unseen, plays a critical role in lithium battery performance. As this essay explored, understanding its definition, measurement, and impact empowers better battery management. By tracking internal resistance, we can diagnose health, predict lifespan, and optimize usage in applications from phones to electric vehicles. By mastering this hidden metric, we unlock the full potential of lithium technology, powering a more sustainable future.


About Semco – Semco University is an educational website that is catering to the needs of students and researchers. Offering information on Lithium-ion batteries. The resources and content are compiled from various sources including manufacturers, test labs, crowdsourcing, etc. Our motto is to provide a viable resource for companies, students, and enthusiasts interested in participating in the Li-ion Battery industry. Our initiative is to make people aware of the benefits, and opportunities of the revolutionary Lithium Batteries for multiple applications.

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