In the field of new energy vehicles, power batteries, as the "energy heart" of vehicles, carry the heavy responsibility of providing continuous power for the whole vehicle. For the engineers of the main engine factory, to have a deep understanding of the basic concept, composition structure, working principle and key performance indicators of the power battery is to master the three core technologies of new energy vehicles-battery, an indispensable link in motor and electronic control. This article will introduce in detail the definition, composition, working mechanism of power battery and its role in new energy vehicles to help engineers master this core technology systematically.

I. Definition of power battery

power Battery, as its name implies, is a battery specially used to provide electric energy for power system. Different from lead-acid batteries used in traditional automobiles, power batteries usually adopt lithium-ion battery technology, which has the advantages of high energy density, high power output and long service life. It is the core component of the new energy automobile driveline, which directly determines the mileage, acceleration performance and safety of the vehicle.

The power battery is not just a single battery, but a battery module composed of multiple single battery packs, and then a battery module composed of battery pack, and finally through the battery management system (BMS) A complex system for monitoring and management.

II. Composition and structure of power battery

the power battery system mainly consists of the following parts:

1. Single battery

single battery is the most basic unit of power battery system, usually lithium ion battery unit. The single battery includes components such as positive electrode material, negative electrode material, electrolyte, separator and Battery shell. Cathode materials usually include ternary materials, lithium iron phosphate, etc., and graphite materials are mostly used for negative electrodes. The electrolyte is responsible for ion conduction, and the diaphragm prevents the positive and negative electrodes from directly contacting and causing short circuit.

2. Battery module

multiple single cells are combined into battery modules in a certain series-parallel mode. Through the module structure design, the overall voltage and capacity of the battery can be improved, and heat dissipation and maintenance are convenient at the same time. The battery module is equipped with temperature sensor and current sensor for real-time monitoring of battery status.

3. Battery pack

battery pack is a battery system composed of multiple battery modules, equipped with Shell, cooling system, insulation device and safety protection device. Battery pack ensure the safety and reliability of power batteries through professional design, and prevent potential safety hazards such as mechanical shock, overheating and short circuit.

4. Battery management system (BMS)

III. Working principle of power battery

the core function of the power battery is to convert chemical energy into electric energy through electrochemical reaction and drive the motor to operate, thus realizing the power output of the vehicle.

When the power battery is discharged, the lithium ion in the negative electrode material moves to the positive electrode material through the electrolyte, and at the same time the electron flows through the external circuit, forming a current output to the motor of the whole vehicle. When charging, the current direction is opposite, and lithium ions migrate from the positive electrode to the negative electrode to realize energy storage.

This process requires that the internal materials of the battery have good ion conductivity and electrochemical stability, and at the same time requires the structural design of the battery to ensure the efficient flow of ions and electrons.

IV. Key performance indicators of power batteries

the performance of power batteries directly affects the overall performance of new energy vehicles. The main indicators include:

1. Energy densityEnergy density refers to the electric energy that can be stored per unit weight or volume of battery, which is usually expressed in Wh/kg or Wh/L. High energy density means that the battery can provide a longer range, which is an important goal of power battery design.

2. Power density

power density refers to the maximum power that can be released per unit weight or volume of the battery per unit time. High power density ensures that the battery can provide sufficient current support under high load conditions such as acceleration and climbing.

3. Cycle life

cycle Life is the number of times that the capacity of the battery remains above a certain proportion (usually 80%) after the charge and discharge cycle. Long service life not only reduces the replacement cost, but also ensures the stable performance of the vehicle for long-term use.

4. Security

power batteries must have high safety performance, which can prevent overcharge, overdischarge, short circuit, thermal runaway and other dangers. The battery design and management system need to adopt multiple safety protection measures to ensure the safety and reliability of the vehicle during use.

the charging and discharging rate determines the response speed and charging efficiency of the battery, which is directly related to the dynamic response and charging time of the vehicle. Reasonable design can improve charging speed and power output on the premise of ensuring safety.

V. The role of power batteries in new energy vehicles

power Battery is the power source of new energy vehicles, which determines the mileage and power performance of the whole vehicle. Its performance directly affects the market competitiveness and user experience of vehicles.

In electric vehicles, power batteries work together with motors through electronic control systems to achieve efficient energy conversion and power output. The battery management system ensures that the battery is in the best working condition, extending the service life and ensuring safety.

In addition, power Battery it also undertakes the task of energy recovery, such as braking energy recovery, which converts the energy generated during vehicle braking into electric energy storage and improves the overall energy utilization efficiency.

VI. Key knowledge points that power battery engineers need to master

• battery material characteristics: understand the performance of positive and negative electrode materials, electrolyte and separator and its influence on battery performance.
• Battery structure design: Master the design principles and thermal management scheme of single battery, module and battery pack.
• Battery Management System: familiar with the functions and algorithms of BMS and its role in security protection and balanced control.
• Safety testing and standards: understand the safety testing methods of power batteries and related industry standards to ensure that products comply with safety specifications.
• Performance parameter evaluation: able to analyze and evaluate key indicators such as battery energy density, power density, cycle life and so on, providing support for vehicle performance optimization.

As the core energy unit of new energy vehicles, power battery has complex technology and strict requirements. Only by deeply understanding the composition, working principle and key performance indicators of power batteries can engineers of the main engine factory realize effective coordination in the three core technical fields of batteries, motors and electronic controls, promote the quality improvement and performance optimization of new energy vehicle products.