Comparative Analysis of Conductive Agents in Conventional Lithium Batteries
Overview
As the commercialization of lithium batteries becomes increasingly widespread, the role of conductive agents in lithium batteries is crucial during the charge-discharge process on the surface of anode materials. During battery discharge, lithium ions in the pores enter the anode active material, causing an increase in current and polarization, which makes discharge difficult.
To ensure excellent charge and discharge performance, a certain amount of conductive agent is usually added to the electrode plates.
Overview of Lithium Battery Conductive Agents
Main conductive materials used in lithium-ion batteries include traditional conductive agents like SUPER-P, KS-6, conductive graphite, carbon nanotubes (CNTs), graphene, and carbon fibers such as VGCF. Each of these conductive agents has its own advantages and disadvantages.
Applications of Conductive Agents in Lithium Batteries
- SP (Super-P)
- Current Usage: Predominantly used as a conductive agent in domestic lithium-ion batteries.
- Properties: Carbon black has good ionic and electrical conductivity. Its large specific surface area helps in adsorbing electrolytes, improving ionic conductivity. Carbon black also forms a support structure through primary particle aggregation, creating a chain-like conductive structure, enhancing the material’s electrical conductivity.
- Graphite Conductive Agent
- Type: Primarily synthetic graphite.
- Comparison: Compared to synthetic graphite used in cathode materials, synthetic graphite as a conductive agent has smaller particles, aiding in electrode particle compression and improving ionic and electrical conductivity.
- CNT Conductive Agent
- Usage: Over 50% application in digital batteries, lower in power batteries.
- Trends: With the increasing demand for energy density, rate capability, and cycle life in power batteries, the application of CNT conductive agents is gradually increasing.
- Ketjen Black
- Advantages: Requires a very low addition amount to achieve high conductivity, maintaining a competitive position in the market. Its unique fibrous form provides multiple conductive contact points and more conductive paths, thus requiring less addition to achieve high conductivity. Ketjen Black is currently being used or tested by the top 10 lithium battery manufacturers.
Content of Conductive Agents
a) Role: Conductive agents provide channels for electrical movement.
- Optimization: An optimal amount can achieve high discharge capacity and good cycle performance. Too little results in fewer conduction paths, hindering high-current charge-discharge, while too much reduces the relative content of active materials, decreasing battery capacity.
b) Impact on Electrolyte Distribution:
- Electrolyte Distribution: Conductive agents affect the distribution of electrolytes within the battery system. High content can cause electrolyte concentration at one electrode, leading to slower lithium ion transport and higher polarization, affecting overall battery performance.
c) Optimal Content:
- Balance: Exceeding the optimal amount reduces electrode density and capacity, while too little decreases active material utilization and high-rate discharge performance.
Future Prospects for Lithium Battery Conductive Agents
- Materials: Both CNTs and graphene can be made into conductive pastes, although they are currently more expensive than conventional carbon black (SP).
- Market Trends: Carbon black is a mature and stable conductive agent. As CNTs and graphene scale up in production, their prices are expected to drop, making their future application prospects promising.
By ensuring the right balance and choice of conductive agents, lithium batteries can achieve improved performance and longer life cycles, meeting the growing demands of various applications.