The fundamental technologies of electric vehicles primarily encompass batteries, motors, and electronic controls. Among these, the power battery plays a pivotal role in determining the driving range and charging speed of electric vehicles.

1. Introduction to New Energy Vehicle Power Batteries:

Power batteries serve as the lifeblood of electric vehicles, functioning both as the primary power source and an energy storage device. They play a pivotal role in the current constraints faced by electric vehicles, requiring advancements in high specific energy, high specific power, prolonged service life, and cost efficiency for electric vehicles to effectively compete with their fuel-powered counterparts.

1.1) Common Terminology and Performance Metrics for Electric Vehicle Power Batteries:

State of Charge (SOC): This indicates the remaining battery capacity as a percentage of the total capacity.

Performance Status (State Of Health, SOH): Provides critical information about the battery's health.

Battery Management System (BMS): Monitors real-time power battery parameters, conducts fault diagnosis, estimates SOC and mileage, offers protection against short circuits, monitors leaks, provides display alarms, and allows charge/discharge mode selection. BMS ensures the efficiency, reliability, and safety of electric vehicles.

Specific Energy (Wh/kg): Represents the amount of electrical energy released by the electrode material per unit mass, indicating the electric vehicle's endurance in pure electric mode.

Specific Power (W/kg): Denotes the power provided by the battery per unit mass, crucial for evaluating acceleration performance, maximum speed, and overall power capabilities of electric vehicles.

Cycle Life: Reflects the number of charge and discharge cycles a battery can undergo in a week, a significant indicator of a power battery's lifespan. More cycles translate to a longer-lasting battery. This also involves the rate of battery discharge, quantified as discharge speed.

Battery Discharge C-rate (C): Indicates the rate of battery discharge; a 1C discharge signifies the entire battery capacity being discharged within 1 hour.

Depth of Discharge (DOD): Represents the ratio of discharged capacity to the battery's rated capacity.

1.2) Performance Requirements for Electric Vehicle Power Batteries:

As the primary energy storage unit in vehicles, electric vehicle batteries must possess not only sufficient energy to fulfill specific driving cycles and distances but also deliver maximum power to achieve the desired acceleration performance. Consequently, power batteries are expected to exhibit excellent charge and discharge capabilities, high specific power and energy, affordability, and user-friendly maintenance procedures. These characteristics are imperative for ensuring the seamless operation of electric vehicles.

Power Battery Performance Requirements for Electric Vehicles:

1. Pure Electric Vehicles:

High Specific Energy and Specific Power: The battery must possess high specific energy and specific power, allowing continuous discharge not exceeding 1C and peak discharge not exceeding 3C. Additionally, during feedback braking, the battery should accept pulse current charging up to 5C.

Deep Discharge Capability: The battery should not be adversely affected when deeply discharged (up to 80%), ensuring it can achieve full load power and complete discharge when necessary.

Advanced Management Systems: The battery management system and thermal management system must accurately display the remaining power of the battery pack and effectively control the operating temperature.

2. Hybrid Cars:

Series Hybrid Vehicles: These vehicles, driven solely by electric motors, require high SOC levels. Battery requirements are akin to pure electric vehicles, though the battery capacity can be smaller.

Parallel Hybrid Vehicles: For these vehicles, the battery capacity can be smaller, but the battery must provide instantaneous power sufficient for vehicle acceleration and climbing needs.

High Peak Power: The battery should deliver high peak power, supporting short-term high-power charging and discharging.

Long Cycle Life: The battery must endure over 1,000 deep discharge cycles, ensuring prolonged usability.

Optimized SOC Range: It is crucial to maintain the battery's SOC within the range of 50% to 80% whenever possible, enhancing the battery's overall lifespan and performance.

3. Types of Power Batteries in Electric Vehicles:

1. Chemical Battery:

Battery: Primarily designed for long-term medium current continuous discharge, including lead-acid batteries, nickel-gold house batteries, and carp-ion batteries.

Fuel Cell: A power generation device converting chemical energy stored in fuel and oxidant into electrical energy through electrode reactions.

2. Physical Battery:

Super Capacitor:Features high power density but limited battery capacity, serving as a bridge between traditional capacitors and batteries. It stores electric energy through extreme electric energy quality.

Flywheel Battery: Utilizes principles similar to energy generated during a rotating flywheel's motion to facilitate charge and discharge.

Solar Battery: Utilizes solar panels to directly convert light energy into electrical energy through the photoelectric effect or photochemical effect.

3. Biobattery:

A device employing biochemical reactions to generate electricity. For instance, microbial batteries use anodes replacing natural electron acceptors like oxygen or nitrate, generating electrical energy through continuous electron transfer, capturing energy from microbial metabolism for electrical current production.

2. Battery Technologies in Electric Vehicles:

1) Lead-Acid Battery:

Lead-acid batteries utilize metallic lead as the negative electrode, lead dioxide as the positive electrode, and sulfuric acid as the electrolyte. Discharge reactions form lead sulfate, which reverses during charging. Types include traditional maintenance-free and valve-regulated sealed lead-acid batteries, differing in electrolyte and tank structure.

2) Ni-MH Battery:

Nickel-metal hydride batteries use a hydrogen storage alloy as the negative electrode, nickel oxide as the positive electrode, and a potassium hydroxide aqueous solution as the electrolyte. Charging causes hydrogen to move to the negative electrode, reversing during discharge. They offer high specific energy, power, discharge rates, and fast charging, without notable memory effect.

3) Lithium-Ion Battery:

Lithium-ion batteries, pioneered by Japan's Sony Corporation in 1990, utilize lithium compounds and lithium-carbon interlayer compounds for positive and negative electrodes, with an organic solution electrolyte. Lithium ions shuttle between electrodes during charge and discharge. Known for high voltage and specific energy, they consist of positive/negative electrodes, electrolytes, separators, and casings.

3. Key Technologies for Power Batteries:

1) Battery Electrochemistry Technology:

Critical for battery performance, this involves chemical reactions and electron flow inside the battery, influencing energy density, charging speed, lifespan, safety, and cost. Innovations in these areas significantly impact battery characteristics.

2) Battery Management System (BMS):

A crucial component, BMS monitors battery status, balances cell charge and temperature, ensuring safe operation. Advanced BMS technology enhances performance, lifespan, and safety, promoting efficient battery use.

3) BMS Construction and Parts Suggested

4) Charging Technology:

Fast Charging: Utilizes methods like DC fast charging, reducing charging times significantly and enhancing electric vehicle usability.

Wireless Charging: Achieved through electromagnetic induction or resonance, enhancing charging convenience.

5) Energy Density Improvement:

Enhancing battery energy density, achieved by improving materials and structures, increases electric vehicle range, making them more practical for daily use.

6) Cycle Life and Safety:

Improving cycle life extends battery service, reducing replacement costs. Ensuring safety involves preventing issues like overcharge, over-discharge, and short circuits, enhancing overall reliability.

Significance of Research on Power Battery Technologies:

Research in power battery technologies drives a sustainable transportation revolution. It reduces greenhouse gas emissions, mitigates climate change, improves air quality, and lessens dependence on limited fossil fuels. Advancements increase energy density, charging speed, lifespan, and decrease manufacturing costs, making electric vehicles more accessible. This fosters large-scale adoption of clean energy transportation, ensuring environmental sustainability and energy security.